aas journal march 2012

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March2012

SOCIETY JOURNALSocietyMeeting

Monday,March12at8:00pm

AnAmateurSearchforExplodingStars

In just a few years, Stu Parker from Oxford in Canterbury has established himself as one of the

most successful discoverers of supernovae. To date, he has 23 personal discoveries to his credit,

including a number that are of particular scientific importance. He gets a real kick out of working

with the professional astronomers who rely on these discoveries to advance our understanding of

supernovae.

Stu will give a talk about what motivated him to start hunting supernovae, the BOSS group he is partof, the results of the Hubble Space Telescope studies of SN2011iv, as well as current thinking about

some of his other discoveries. He will also describe his telescopes and observing strategies.

By way of introduction, Grant Christie will provide a brief summary of various types of supernovae.


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SOCIETYJOURNAL,MARCH20122

DatesforyourDiary

1. AucklandSocietyAGM,MondayApril16that8:00pm.SeenoticeP4.

2. DarkSkyObservingNight,SaturdayApril28th.DetailsinAprilJournal.

3. StarlightConference,1113June,LakeTekapo.SeenoticeP13.

4. RASNZConference,1517JuneinCarterton.SeeRASNZWebsitefordetails.

Big Attendance at First Film Night of 2012By Gavin LoganS

tarting from the camp fire at night and taking animaginary journey through the Universe back to the

beginning of time, Februarys film, Journey to the Edge of

the Universe, gave the audience of well over 50 Societymembers a tour through much of the known Universe, aswell as speculating about the unknown. This voyageacross the Cosmos, took the audience from the Earth,past the Moon and our neighbouring planets, out of ourSolar System, to the nearest stars, nebulae and galaxiesand beyond.

Using images taken from the Hubble telescope and crea-tive graphics, Journey to the Edge of the Universe ex-plored the science and history behind both the Solar Sys-tem and distant celestial bodies.

This cinema tour to the edge of Universe showed somedazzling images of the Moon, the surface of Venus, thetornadoes, volcanoes and canyons of Mars, the rings ofSaturn, the ferocious storms of Jupiter, the erupting gey-sers of Triton (Neptune's moon), the surface of the Sun,

exploding stars, magnetars, interacting galaxies, nebulas,newborn stars, quasars, black holes consuming stars, andother deep space objects.

The journey through the Universe is also a journey back intime and this film related the progress across the Universeto the past history of the Earth. The nearest possibly in-habited planets lie 90 light years away, before the age oftelevision. The exploding Crab Nebula is 6300 light yearsoff, dating from the time of the construction of Stone-

henge. The great Andromeda Galaxy lies at a distancecorresponding to 2.5 million BC, before humans existed,at the time our ape-like ancestor Lucy lived in Africa. Thenearest quasar 3C 273 lies 2 billion light years away, be-fore life on Earth moved from sea to land and The HubbleSpace Telescope reveals galaxies so remote, we see themas they were before the Earth even existed.

A sizeable audience watching a Journey to the Edge ofthe Universe.

Geysers on Triton.

Wanted Sidewalk AstronomersA community facility in West Auckland has some of the best dark skies within Auckland City. There is an op-portunity for both telescope and naked-eye observing with outstanding views to the south and the west andwe want to share this with our wider community.If you have a good knowledge of the night sky, are comfortable talking to strangers, and are available for upto four evenings during 2012, then please consider being part of this outreach.This is a developing project so flexibility and reliability is important. Initially, there will be reimbursement oftravel costs.If YOU have the enthusiasm to share your passion for the night sky, contact [email protected].


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3WWW.ASTRONOMY.ORG.NZ

CalendarofEventsfor2012April 2012 ProgrammeMarch 2012 Programme

Fri 2 7:30pm YoungAstronomerswithMargaretArthur

Mon 5 8:00pm IntroductiontoAstronomywithBernieBrenner:Wondersofthe SolarSystem(part2)

Mon 12 8:00pm SocietyMeetingwithStuartParker:FindingSupernovae

Mon 19 8:00pm AutumnObservingNightwithAndrewBuckingham

Wed 21 7:30pm CouncilMeetingMon 26 8:00pm FilmNightwithGavinLogan:

StargazingLive

Fri 7 7:30pm YoungAstronomerswithMargaretArthur

Mon 9 8:00pm IntroductiontoAstronomywithBernieBrenner

Mon 16 8:00pm AnnualGeneralMeetingMon 23 8:00pm FilmNightwithGavinLoganSat 28 DarkSkyObservingNight,

Wainui

2012 ProgrammeThe society has over 55 meetings and events planned during2012. Please note that to allow for the Moon on our observingnights we have made some adjustments to the schedule.For 2012 our current regular monthly programme is:

First Mondayof Month - Introduction to AstronomyCoordinator: Bernie BrennerAn introductory astronomy course using a video lecture or

documentary followed by a tutorial. This year we will beincluding the BBC series 'Wonders of the Solar System' and'Wonders of the Universe'.

First Friday of Month - Young AstronomersCoordinator: Margaret ArthurThis is an interactive session on current topics with plenty ofquestion and answer time. Aimed at the younger members ofthe Society, suitable for age 7 years and up.

Second Mondayof Month - Monthly MeetingCoordinator: Grant ChristieThe Monthly Meeting features a talk by a guest speaker (whenavailable) or a current astronomical documentary.

Third Mondayof Month - Practical AstronomyCoordinator: Bill ThomasThis session is all about learning the night sky and using yourtelescope. Includes observing nights each quarter.

Fourth Mondayof Month - Film NightCoordinator: Gavin LoganScreening a wide range of astronomy and sciencedocumentaries.

Telescope viewing is normally available after each meeting ifthe weather permits. The meetings are aimed at a wide rangeof abilities, from the beginner to the more experienced.

More information on upcoming meetings will be listed in thejournal or is available on the AAS website at:http://www.astronomy.org.nz/pages/events.aspx

Welcome to New Members

Beth van der Loeff (ordinary)

Berin Hunter (ordinary)

Robert Hicks (country)

Rachel Kelly (ordinary)Andrew Horne (family)

Rolf Olsen (ordinary)

Chris Jones (ordinary)

Jacqui Anderson (country)

Vivienne Cumberland

(family)

Brenda Town (family)

Jean-Pierre Hallaux

(ordinary)

Theresa Saolotoga (family)

Russell Ridout (country)

Jonathan Green (ordinary)

Tony Holder (ordinary)

Kevin Oldham (ordinary)Susan Showbridge

(ordinary)

Bob Howard (ordinary)

Rox Orange (ordinary)

Arthur Gay (ordinary)

Jordan Griffiths (youth)

Helena Barnes (youth)

Robert Johnson (family)

Steve Hennerley (ordinary)

Matt Sandilands (ordinary)

Film Night Monday 26 March 8:00pmWith Gavin LoganStargazing Live (January 2012) with Brian Cox and DaraO Briain covers a range of the latest topics in astronomy

in a colourful and sometimes humorous way. Preserving

the dark sky from light intrusion and discovering new

planets around other stars are amongst subjects covered

by this film. It is 50 minutes long.

It will be followed by Ocean Origins, which is a brief, but

highly colourful film, showing how life first appeared on

Earth and diversified after the first bacteria appeared until

the first vertebrate emerged onto dry land. It has some

exceptional photography and is 40 minutes long.
http://www.astronomy.org.nz/pages/events.aspxhttp://www.astronomy.org.nz/pages/events.aspx


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Aurora Astronomy School

The Aurora Astronomy School is a unique opportunity forYear 13 students, and will take place 16th to 20th April2012, in the Easter vacation. The free camp will be held atthe University of Canterbury, and the observatory at Mt John.On campus we will talk about the Universe past, present andfuture, the life cycles of stars, planet exploration, extraterres-

trial life and more. We will then travel to the Mt John Obser-vatory at Tekapo, where we will explore our cosmicneighbourhood with modern astronomical instruments. Theprogramme will contain a mix of seminars and practicalwork.

The closing date for applications for this camp is Friday 16thMarch. More details are on the application form at http://w w w . o u t r e a c h . c a n t e r b u r y . a c . n z / d o c u m e n t s /aurora_astro_12.pdf
http://www.outreach.canterbury.ac.nz/documents/aurora_astro_12.pdfhttp://www.outreach.canterbury.ac.nz/documents/aurora_astro_12.pdfhttp://www.outreach.canterbury.ac.nz/documents/aurora_astro_12.pdfhttp://www.outreach.canterbury.ac.nz/documents/aurora_astro_12.pdfhttp://www.outreach.canterbury.ac.nz/documents/aurora_astro_12.pdfhttp://www.outreach.canterbury.ac.nz/documents/aurora_astro_12.pdfhttp://www.outreach.canterbury.ac.nz/documents/aurora_astro_12.pdfhttp://www.outreach.canterbury.ac.nz/documents/aurora_astro_12.pdfhttp://www.outreach.canterbury.ac.nz/documents/aurora_astro_12.pdfhttp://www.outreach.canterbury.ac.nz/documents/aurora_astro_12.pdfhttp://www.outreach.canterbury.ac.nz/documents/aurora_astro_12.pdfhttp://www.outreach.canterbury.ac.nz/documents/aurora_astro_12.pdf


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A Summer FallFrom Cosmo Sparks ReportsA

bright fireball and two sonicbooms ushered the fall of the

world's most recent Martian meteor-ite in Morocco on July 18, 2011.Named Tissint, the 7 kilograms (15pounds) of pieces recovered in De-cember were confirmed officially asthe shergottite type on January 17,2012.As only the fifth known witnessedfall of a Martian meteorite since thefourth in 1962 in Nigeria of the Za-gami meteorite, interest in the Tissintmeteorite is running high. Thesenew pieces gathered off the Moroc-can dessert are considered relatively

fresh, having been subjected to ter-restrial contamination for only sixmonths as compared with otherMartian meteorites collected centu-ries or more after their touchdown.

Christopher Herd (University of Al-berta, Edmonton), chair of the com-

mittee that confirmed the meteor-ite's name and origin, commentedthat studying the crystallization his-

tory of this igneous rock, "we canpeer back and say something aboutthe magma itself and the interior of

Mars, the part of Mars that it camefrom. So in some ways we can proberight in to the inside of Mars

through these kinds of studies."Pieces of Tissint are now in the me-teorite collections at the University ofAlberta, Arizona State University,University of New Mexico, and Uni-versity of Washington. Of the 103separately named and numberedMartian meteorites on the officiallist, shergottites are the most abun-dant type. Cosmochemists will nowbe analyzing samples of Tissint todetermine its igneous crystallizationage, how it compares to the other

shergottites, and what details it re-veals about the Red Planet.

Cosmo Sparks Reports are providedby Planetary Science Research Dis-coveries.

Double DocumentariesBy Gavin LoganA

t Februarys monthly meeting ofthe Society, members were

treated to a double feature of docu-mentary films.The first one entitled Death of aMars Rover told the story of thetwo Mars Rovers, Spirit and Oppor-tunity, and the efforts to save Spiritafter she drove into a quicksand trapand then fell silent over a year ago.When the twin rovers Spirit and Op-portunity landed on Mars in January2004, they were expected to lastninety days. Seven-plus years later,the hardy, remote controlled robotshave proven to be two great explor-ers, trekking miles across the desertlike surface of Mars, climbing moun-tains, scrambling in and out of cra-ters, and surviving many times in thedifficult condition of dust storms andthe extremely cold winters. Poweredby solar charged batteries, lack ofsunlight in winter and dust fromstorms on the solar panels are seri-ous hazards. Opportunity continuesto operate, but Spirit has reachedthe end of the road.The second documentary wasEarths Evil Twin, which covered

the latest information about theplanet Venus.Venus and Earth are roughly thesame size, but have gone on differ-ent paths over the four billion plusyears of the Solar Systems existence.Although roughly the same mass asEarth, Venus is closer to the Sun, isenshrouded in a crushingly denseatmosphere of carbon dioxide andsulphur dioxide creating atmosphericpressure massively greater than onEarth. On its hostile surface, it rains

acid and temperatures reach 470C,which is hot enough to melt tin. Thisdocumentary looked at the latestinformation obtained by the VenusExpress spacecraft in 2006, whichused an infra-red camera to pene-trate the dense atmosphere on theplanet. It detected hurricane-forcewinds masking a blistering volcanicsurface. It also detected lightening,leading scientists to wonder ifchemicals supporting life are possi-ble. Micro-organisms could not sur-vive on the surface, but in the cloudsits much cooler and water vapourexists. There was also evidence ofwater molecules splitting into oxy-gen and hydrogen, which was foundto be dissipating into space.There are no plate tectonics on Ve-nus to release heat and pressurefrom the planets core and when thisfinally surfaces as huge volcanic ac-tion, it resurfaces the planet andreleases massive amounts of carbondioxide into the atmosphere. VenusExpress found that most of Venusssurface was less than 500 millionyears old.

Earths Evil Twin Venus.
http://www.psrd.hawaii.edu/PSRDglossary.html#shergottitehttp://www.psrd.hawaii.edu/PSRDglossary.html#shergottite


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Mars Express Radar Yields Strong Evidence of OceanThat Once Covered Part of Red PlanetFrom Science Daily

ESA's Mars Express has returnedstrong evidence for an ocean

once covering part of Mars. Usingradar, it has detected sedimentsreminiscent of an ocean floor withinthe boundaries of previously identi-fied, ancient shorelines on Mars.The MARSIS radar was deployed in2005 and has been collecting dataever since. Jrmie Mouginot, Institutde Plantologie et d'Astrophysiquede Grenoble (IPAG) and the Univer-sity of California, Irvine, and col-

leagues have analysed more thantwo years of data and found that thenorthern plains are covered in low-

density material."We interpret these as sedimentarydeposits, maybe ice-rich," says DrMouginot. "It is a strong new indica-tion that there was once an oceanhere."The existence of oceans on ancientMars has been suspected before andfeatures reminiscent of shorelineshave been tentatively identified inimages from various spacecraft. Butit remains a controversial issue.Two oceans have been proposed: 4

billion years ago, when warmer con-ditions prevailed, and also 3 billionyears ago when subsurface ice

melted, possibly as a result of en-hanced geothermal activity, creatingoutflow channels that drained thewater into areas of low elevation."MARSIS penetrates deep into theground, revealing the first 60-80metres of the planet's subsurface,"says Wlodek Kofman, leader of theradar team at IPAG."Throughout all of this depth, wesee the evidence for sedimentarymaterial and ice."The sediments revealed by MARSIS

are areas of low radar reflectivity.Such sediments are typically low-density granular materials that havebeen eroded away by water and car-ried to their final destination.This later ocean would however havebeen temporary. Within a millionyears or less, Dr Mouginot estimates,the water would have either frozenback in place and been preservedunderground again, or turned intovapour and lifted gradually into theatmosphere.

"I don't think it could have stayed asan ocean long enough for life toform."In order to find evidence of life, as-trobiologists will have to look evenfurther back in Mars' history whenliquid water existed for much longerperiods.Nevertheless, this work providessome of the best evidence yet thatthere were once large bodies of liq-uid water on Mars and is furtherproof of the role of liquid water in

the martian geological history."Previous Mars Express results aboutwater on Mars came from the studyof images and mineralogical data, aswell as atmospheric measurements.Now we have the view from the sub-surface radar," says Olivier Witasse,ESA's Mars Express Project Scientist."This adds new pieces of informa-tion to the puzzle but the questionremains: where did all the watergo?"

New results from the MARSIS radar on Mars Express give strong evidence for a former ocean of Mars. The radar detectedsediments reminiscent of an ocean floor inside previously identified, ancient shorelines on the red planet. The oceanwould have covered the northern plains billions of years ago. (Credit: ESA, C. Carreau)


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2012AstronomicalYearbook

The2012editionisnowavailabletomembersatthespecialprice

of$1400(+$2.00postage)percopywhenpurchasedfromAAS.

PurchasescanbemadeatallAASmeetingsoryoucanorderfrom

[email protected]

orbyphoneon(09)4735877.

Galaxy in a BucketFrom Sky & Telescope

Anew study published in the Jan. 26issue of Nature highlights a rising

theme in the symphony of astrophysics

research: When you cant go to thestars, bring the stars to you.

In this case, an international team ofresearchers studied where galaxies gettheir magnetic fields by zapping a minus-cule rod with lasers to make a proxy ofthe environment in a forming galaxy.Their result the creation of tinyseed fields by a well-known theoreti-cal effect supports current ideas ofhow large-scale galactic fields could ariseand adds to previous arguments againstmore peculiar explanations.

Vast magnetic fields exist in all galaxytypes and even on cluster and superclus-ter scales. Its thought that turbulence

and rotation in forming galaxies mayamplify already-present weak fields, cre-ating large-scale ones, explains LawrenceWidrow (Queens University, Ontario),who was not involved with the newstudy. Where these seed fields comefrom remains an open question. Theycould be primordial, arising from fancyphysics cartwheels in the early Universe.But such fields are fairly exotic,Widrow says, and require a lot of as-sumptions about conditions at the cos-mic dawn. A better option would beastrophysical causes fields expelled by

the first stars when they died explosively,or by madly gobbling black holes in ga-lactic cores. Or, created by the Biermannbattery process.

In a nutshell, a Biermann battery is thespontaneous creation of a magnetic fieldwhen a curved shock wave goes throughhot, ionized gas. Its a well-known theo-retical effect, and astronomers have sug-gested it before as a solution to the cos-mic magnetic field question. To test theidea, researchers set up a 500-micrometer-wide carbon rod in a cham-ber of helium gas and vaporized the rodwith laser beams. The supersonic expan-sion of the vaporized carbon drove ashock in the gas, which, because theshock wasnt perfectly spherical, createda magnetic field, explains coauthor Fran-cesco Miniati (ETH Zurich, Switzerland).Such fields could easily arise in the col-lapsing gas that forms galaxies, whereover several hundred million years gasdynamics would augment the fieldsenough to affect the galaxys evolution,Miniati and his colleagues conclude.How exactly those effects would mani-

fest is still mysterious, he says. But be-cause magnetic fields affect the motionof interstellar gas, they may regulate star

formation in molecular clouds and con-fine superspeedy particles called cosmicrays.

The result matches whats expectedtheoretically from shocks during thecollapse of matter into protostars andgalaxies, but its the first experiment tounequivocally produce the effect in alab, says Dongsu Ryu (Chungnam Na-tional University, South Korea), who haswritten several review papers withWidrow on the origin of the Universesmagnetic fields.

Miniati acknowledges that it is a boldextrapolation to draw conclusions froman experiment roughly a trillionth of atrillionth the size involved in intergalacticfields. But due to the physics involved inthis particular case hes confident thatsuch scaling is possible.

The Biermann battery could work in anycollapsing or accreting material, meaningit could provide the seed for stars fields,too. Where it and the other theories cant reach is into gigantic cosmicvoids, where astronomers have also

found hints of weak magnetic fields. Buta 2010 paper by Miniati and Tony Bell(Oxford University) suggested that acharge imbalance caused by cosmic rayscould explain those fields, providing an-other astrophysical explanation that re-moves the need for exotic primordialfields.

Reality jibes with simulations in thiscomposite image of a shock wave. Onthe left is a laser-produced shock wave;on right, a simulation of a collapsingshock wave from before galaxies startedforming. Brighter colours show theshock region of higher density or tem-perature.

A. Ravasio and A. Pelka / LULI, J.Meinecke and C. Murphy / OxfordUniv., F. Miniati / ETH Zurich
http://www.nature.com/nature/journal/v481/n7382/full/nature10747.htmlhttp://www.skyandtelescope.com/community/skyblog/newsblog/Another-Origin-for-Cosmic-Rays-134404253.htmlhttp://www.skyandtelescope.com/community/skyblog/newsblog/Another-Origin-for-Cosmic-Rays-134404253.htmlhttp://arxiv.org/abs/1001.2011v2http://arxiv.org/abs/1001.2011v2http://www.skyandtelescope.com/community/skyblog/newsblog/Another-Origin-for-Cosmic-Rays-134404253.htmlhttp://www.skyandtelescope.com/community/skyblog/newsblog/Another-Origin-for-Cosmic-Rays-134404253.htmlhttp://www.skyandtelescope.com/community/skyblog/newsblog/Another-Origin-for-Cosmic-Rays-134404253.htmlhttp://www.skyandtelescope.com/community/skyblog/newsblog/Another-Origin-for-Cosmic-Rays-134404253.htmlhttp://www.nature.com/nature/journal/v481/n7382/full/nature10747.html


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Millisecond Pulsar Paradox: Stellar AstrophysicsHelps Explain Behaviour of Fast Rotating NeutronStars in Binary SystemsFrom Science DailyP

ulsars are among the most exoticcelestial bodies known. They have

diameters of about 20 kilometres, but atthe same time roughly the mass of ourSun. A sugar-cube sized piece of its ultra-compact matter on Earth would weighhundreds of millions of tons. A sub-classof them, known as millisecond pulsars,spin up to several hundred times persecond around their own axes. Previousstudies reached the paradoxical conclu-

sion that some millisecond pulsars areolder than the Universe itself.Astrophysicist Thomas Tauris from theMax Planck Institute for Radio Astron-omy and the Argelander Institute forAstronomy in Bonn could resolve thisparadox by computer simulations.Through numerical calculations on thebase of stellar evolution and accretiontorques, he demonstrated that millisec-ond pulsars lose about half of their rota-tional energy during the final stages ofthe mass-transfer process before thepulsar turns on its radio beam. This re-

sult is in agreement with current obser-vations and the findings also explainwhy radio millisecond pulsars appear tobe much older than the white dwarfremnants of their companion stars --and perhaps why no sub-millisecondradio pulsars exist at all. The results are

reported in the February 03 issue of thejournal "Science."Millisecond pulsars are strongly magnet-ized, old neutron stars in binary systemswhich have been spun up to high rota-tional frequencies by accumulating massand angular momentum from a com-panion star. Today we know of about200 such pulsars with spin periods be-tween 1.4 to 10 milliseconds. These arelocated in both the Galactic Disk and in

Globular Clusters.Since the first millisecond pulsar wasdetected in 1982, it has remained achallenge for theorists to explain theirspin periods, magnetic fields and ages.For example, there is the "turn-off"problem, i.e. what happens to the spinof the pulsar when the donor star termi-nates its mass-transfer process?"We have now, for the first time, com-bined detailed numerical stellar evolu-tion models with calculations of thebraking torque acting on the spinningpulsar," says Thomas Tauris, the authorof the present study. "The result is thatthe millisecond pulsars lose about half oftheir rotational energy in the so-calledRoche-lobe decoupling phase." Thisphase describes the termination of themass transfer in the binary system.Hence, radio-emitting millisecond pul-

sars should spin slightly slower thantheir progenitors, X-ray emitting millisec-ond pulsars which are still accretingmaterial from their donor star. This isexactly what the observational dataseem to suggest. Furthermore, thesenew findings help explain why somemillisecond pulsars appear to have char-acteristic ages exceeding the age of theUniverse and perhaps why no sub-millisecond radio pulsars exist.

The key feature of the new results isthat it has now been demonstrated howthe spinning pulsar is able to break outof its so-called equilibrium spin. At thisepoch the mass-transfer rate decreaseswhich causes the magnetospheric radiusof the pulsar to expand and therebyexpel the collapsing matter like a propel-ler. This causes the pulsar to lose addi-tional rotational energy and thus slowdown its spin rate."Actually, without a solution to the"turn-off" problem we would expectpulsars to even slow down to spin peri-ods of 50 to 100 milliseconds during theRoche-lobe decoupling phase," con-cludes Thomas Tauris. "That would be inclear contradiction with observationalevidence for the existence of millisecondpulsars."

Pulsars are among the most exotic celestial bodies known. They have diameters of about 20 kilometres, but at the same timeroughly the mass of our Sun. A sugar-cube sized piece of its ultra-compact matter on Earth would weigh hundreds of millions oftons. A sub-class of them, known as millisecond pulsars, spin up to several hundred times per second around their own axes. Previ-ous studies reached the paradoxical conclusion that some millisecond pulsars are older than the Universe itself. (Credit: NASA / God-dard Space Flight Center / Dana Berry)


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exploring the properties of close binaries

in extragalactic stellar populations.

Comparing its position with the approxi-mately 900 novae in W. Pietsch's M31nova catalogue revealed that PNVJ00423804+4108417 was located aboutsix arc seconds from the catalogued posi-tion of M31N 1923-12c, the nova discov-ered by Edwin Hubble on December 11,1923. Given that the positions of M31novae from early photographic surveyswere typically reported to a precision ofonly ten arc seconds, and that He/Nspectra are often associated with recur-

rent novae, astronomers considered thepossibility that M31N 1923-12c and PNVJ00423804+4108417 represented twooutbursts arising from the same novaprogenitor. To explore this possibilityfurther, F. Schweizer (Carnegie Observa-tories) located Hubble's original plate inthe Carnegie Observatories archives andperformed an eyeball comparison of theposition of Hubble's nova with that ofPNV J00423804+4108417, finding themto match within ~1.5". You can see the

images for yourself here.

After digitally scanning the Hubble plateand comparing the position of the nova

relative to those of three nearby USNOreference stars, analysis revealed thatM31N 1923-12c was located

at R.A. = 00 42 38.06; Decl. = 41 0841.0 (J2000). Hubble's M31N 1923-12ca n d t h i s y e a r ' s P N VJ00423804+4108417 are the same ob-ject!

88 years and a handful of days later,PNV J00423804+4108417 representsthe second recorded outburst of therecurrent nova M31N 1923-12c. Like thetelescope named for him, Hubble's leg-

acy to astronomy and astrophysics con-tinues to grow to this very day. Way to

go, Edwin.

On December 11, 1923, Edwin Hub-ble discovered a nova in the Andro-

meda galaxy. Novae occurring in our

Milky Way's sister galaxy are not thatuncommon. There have been over 800novae detected in M31 in the last 100years. Hubble's 1923 discovery becameknown as M31N 1923-12c, the thirdnova discovered in December of 1923.

Fast forward to January 21, 2012. K.Nishiyama and F. Kabashima report thediscovery of a possible nova in M31 andit is given the preliminary designation,PNV J00423804+4108417. If this proves

to be a new nova in M31 it will get thepermanent designation M31N 2012-01b, the second novae discovered inJanuary 2012. A day later a spectrum istaken with the 9.2m Hobby-Eberly Tele-scope using the Marcario Low-Resolution Spectrograph, confirmingthat PNV J00423804+4108417 is a novain M31, and that it is a member of theHe/N spectroscopic class.

Whats even more interesting, however,is that the new nova likely comes fromthe same progenitor as Hubbles 1923nova!

Classical novae are a subclass of cata-clysmic variable stars. They are semi-detached binary systems where anevolved, late-type star fills its Roche lobeand transfers mass to its white dwarfcompanion. If the mass accretion rateonto the white dwarf is sufficiently low,it allows this gas to pile up and becomedegenerate. Eventually, after thousandsto tens of thousands of years, a thermo-nuclear runaway ensues in this highlypressurized layer of gas, leading to anova eruption. These eruptions can

reach an absolute magnitude as brightas MV 10, making them among themost luminous explosions in the Uni-verse. Their high luminosities and rates,about 50 per year in a galaxy like M31,make novae very useful to astronomers

The position of M31N-1923-12c

Artist's rendition of the recurrent nova

RS Oph

Credit: David Hardy/PPARC

Edwin Hubble

Hubbles 1923 Nova in Andromeda Erupts Again!By M ike Simonsen, AAVSO W riters Bureau

Left: A finding chart of PNV J00423804+4108417 (M31N 2012-01b) courtesy of KoichiNishiyama and Fujio Kabashima (Miyaki-Argenteus Observatory, Japan), with the novamarked near the center of the image. Right: A reproduction of Hubble's plate taken onDecember 11, 1923 showing the position of a nova, later designated as M31N 1923-12c (the smudges near the center are Hubble's original ink marks identifying the nova).
http://mintaka.sdsu.edu/faculty/shafter/extragalactic_novae/M31N1923-12c_RN/http://mintaka.sdsu.edu/faculty/shafter/extragalactic_novae/M31N1923-12c_RN/


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11

outer edge of this habitable zone. Beinga gas giant, 16b is not a habitable terres-trial planet. However, an Earth-like

moon, a Goldilocks Moon, in orbitaround this planet could sustain life if itwere massive enough to retain an Earth-like atmosphere. We determined that ahabitable exomoon is possible in orbitaround Kepler-16b, Quarles said.

I asked Quarles how stellar evolutionimpacts these Goldilocks Zones. He toldme, There are a number of things toconsider over the lifetime of a system.One of them is how the star evolves overtime. In most cases the habitable zonestarts out close and then slowly driftsout.

During a stars main sequence lifetime,nuclear burning of hydrogen builds up ahelium in its core, causing an increase inpressure and temperature. This occursmore rapidly in stars that are more mas-sive and lower in metallicity. Thesechanges affect the outer regions of thestar, which results in a steady increase inluminosity and effective temperature.The star becomes more luminous, caus-ing the HZ to move outwards. Thismovement could result in a planet withinthe HZ at the beginning of a stars mainsequence lifetime, to become too hot,and eventually, uninhabitable. Similarly,

an inhospitable planet originally outsidethe HZ, may thaw out and enable life tocommence.

For our study, we ignored the stellarevolution part, said lead author,Quarles. We ran our models for a mil-lion years to see where the habitablezone was for that part of the stars lifecycle.

Being at the right distance from its star isonly one of the necessary conditionsrequired for a planet to be habitable.Habitable conditions on a planet requirevarious geophysical and geochemical

conditions. Many factors can prevent, orimpede, habitability. For example, theplanet may lack water, gravity may betoo weak to retain a dense atmosphere,the rate of large impacts may be toohigh, or the minimum ingredients neces-sary for life (still up for debate) may notbe there.

One thing is clear. Even with all the re-quirements for life as we know it, thereappear to be plenty of planets aroundother stars, and very likely, GoldilocksMoons around planets, orbiting withinthe habitable zones of stars in our gal-

axy, that detecting the signature of lifein the atmosphere of a planet or moonaround another sun seems like only amatter of time now.

Goldilocks MoonsBy M ike Simonsen, AAVSO W riters BureauT

he search for extraterrestrial life out-side our Solar System is currently

focused on extrasolar planets within thehabitable zones of exoplanetary systemsaround stars similar to the Sun. FindingEarth-like planets around other stars isthe primary goal of NASAs Kepler Mis-sion.

The habitable zone (HZ) around a star isdefined as the range of distances overwhich liquid water could exist on thesurface of a terrestrial planet, given adense enough atmosphere. Terrestrialplanets are generally defined as rocky andsimilar to Earth in size and mass. A visuali-zation of the habitable zones around starsof different diameters and brightness andtemperature is shown here. The red re-

gion is too hot, the blue region is toocold, but the green region is just right forliquid water. Because it can be describedthis way, the HZ is also referred to as theGoldilocks Zone.

Normally, we think of planets aroundother stars as being similar to our solarsystem, where a retinue of planets orbitsa single star. Although theoretically possi-ble, scientists debated whether or notplanets would ever be found around pairsof stars or multiple star systems. Then, inSeptember, 2011, researchers at NASAsKepler mission announced the discovery

of Kepler-16b, a cold, gaseous, Saturn-sized planet that orbits a pair of stars, likeStar Wars fictional Tatooine.

This week I had the chance to interviewone of the young guns studying exoplan-ets, Billy Quarles. Monday, Billy and his co-authors, professor Zdzislaw Musielak andassociate professor Manfred Cuntz, pre-sented their findings on the possibility ofEarth-like planets inside the habitablezones of Kepler 16 and other circumbi-nary star systems, at the AAS meeting inAustin, Texas.

To define the habitable zone we calcu-late the amount of flux that is incident onan object at a given distance, Billy ex-

plained. We also took into account thatdifferent planets with different atmos-pheres will retain heat differently. Aplanet with a really weak greenhouseeffect can be closer in to the stars. For aplanet with a much stronger greenhouseeffect, the habitable zone will be furtherout.

In our particular study, we have a planetorbiting two stars. One of the stars ismuch brighter than the other. So muchbrighter, that we ignored the flux comingfrom the smaller fainter companion staraltogether. So our definition of the habit-able zone in this case is a conservativeestimate.

Quarles and his colleagues performedextensive numerical studies on the long-term stability of planetary orbits withinthe Kepler 16 HZ. The stability of theplanetary orbit depends on the distancefrom the binary stars, said Quarles. Thefurther out the more stable they tend tobe, because there is less perturbationfrom the secondary star.

For the Kepler 16 system, planetary orbitsaround the primary star are only stableout to 0.0675 AU (astronomical units).That is well inside the inner limit of habi-tability, where the runaway greenhouseeffect takes over, Billy explained. This allbut rules out the possibility of habitableplanets in close orbit around the primarystar of the pair. What they found wasthat orbits in the Goldilocks Zone fartherout, around the pair of Kepler 16 s low-mass stars, are stable on time scales of amillion years or more, providing the possi-bility that life could evolve on a planetwithin that HZ.

Kepler 16bs roughly circular orbit, about65 million miles from the stars, is on the

Goldilocks Zones around various type stars. Credit: NASA/JPL- Caltech


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SOCIETYJOURNAL,12

A Tale of Two Stars: The Inside Story of Orions BeltFrom Space.comS

tanding upright and shining downupon Earth on these midwinter

nights is the brightest and grandest of all

the constellations: Orion, the MightyHunter.

Three bright stars in line in the middle ofa bright rectangle decorate Orion's belt,which points northward to the clusters ofthe Hyades and Pleiades of Taurus, andsouthward to the Dog Star, Sirius. Aboveand below the belt, we also find twoimmense stars, Rigel and Betelgeuse.

Rigel (the "Left Leg of the Giant"), is ablue-white supergiant star, one of therarest breeds in our galaxy. But withtheir enormous brilliance up to

100,000 times as bright as the Sun blue-white supergiants remain conspicu-

ous over great distances.

In contrast, red supergiants like Betel-geuse ("The Armpit of the Giant") aregigantic bloated globes of cooler gas. Ifsuch a star were to replace the Sun inthe solar system, it might extend beyondMars' orbit.

Star at its primeRigel is one of the most intrinsically lumi-nous of all stars and one of the hottest,apparently just reaching the prime of itslife in the time span of a star and literally"burning the candle at both ends." It hasbeen computed that Rigel's luminosity issomething like 57,000 times that of theSun. The star is about 773 light-yearsaway.

In stark contrast, bright red Betelgeuse isnear the end of its career. It is located522 light-years away, but does not shinewith a steady light.

Betelgeuse is a "pulsating" star, expand-ing and contracting spasmodically with adiameter that varies from 550 to 920times that of the Sun, but so irregular arethese pulsations that no one can predictexactly when it will expand or contract.In trying to describe Betelgeuse manyyears ago, Henry Neely, a lecturer at NewYork's Hayden Planetarium, once notedthat it is "like an old man with hisstrength almost entirely spent, panting inthe asthmatic decrepitude of old age."

Stars produce their energy by fusing hy-drogen into helium deep within theircores. When a star accumulates sufficienthelium in its core, its energy output in-

creases significantly, and it swells into ared giant or supergiant, like Betelgeuse.This is what Rigel will become in a fewmillion years.

In such stars, the core produces succes-

sively heavier elements to balance theincessant crush of gravity. But once thecore begins creating iron, a star's days

are numbered; the formation of ele-ments heavier than iron consumes ratherthan produces energy.

Eventually, since the core can no longersupport the star's vast weight, it col-lapses, triggering a cataclysmic super-nova explosion. Betelgeuse is in its finalstage and could explode in only a fewmillion years.

Colourful starsOne of the pleasures of stargazing isnoticing and enjoying the various coloursthat stars display in dark skies. Thesehues offer direct visual evidence of how

stellar temperatures vary.

Ruddy Betelgeuse and bluish Rigel pro-vide an excellent colour contrast, but wecan easily find other colours as well. Lookat orange-ish Aldebaran and yellowishPollux. And considerably removed fromthe winter groupings is brilliant topaz

Arcturus.

Even as you observe these stellar colours,do you notice that they're recognizable

only for the brightest stars?

This is due to the physiology of the eye,and more specifically, to the fact that thecolour sensors on the retina the cones are insensitive to faint light. Underdim illumination the retinal rods takeover. But their greater light sensitivity isoffset by their colour blindness. This iswhy we see all faint stars as white.

However, if we look at them throughbinoculars or a telescope, their amplifiedbrightness stimulates the cones, whichdetect their colour.

Orion is the brightest and most beautiful of the winter constellations, full of fascinating

objects for the curious skygazer. CREDIT: Starry Night Software


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TheStarlightConference isatLakeTekapo,1113

June2012. From1 Decemberthewebsitewillbe

able to accept online registrations and on line

requests to give an oral or poster paper. Visit

www.starlight2012.orgforfulldetails.

It will be a multidisciplinary conference on the

scientificand cultural benefitsofobservingdark

starlit skies. Themeetingwill be of interest to

RASNZ members and to many other interest

groups in education, tourism, environmental

protectionandtothoseinterested in thecultural

andethnicaspectsofastronomy.Asparticipation

willbe limited,earlyregistrationisencouraged.

TheStarlightConference isjointlyhostedby the

University of Canterbury and by RASNZ, and is

beingsponsoredby theUniversityofCanterbury,

by RASNZ, by the Royal Society of NZ, by

Endeavour Capital Ltd and by the NZ National

CommissiontoUNESCO.

AbridgedfromanearlierpublishednotebyJohn

Hearnshaw.

What Happened Before the Big Bang?By Gavin LoganD

ecembers Film Night Documentaryexamined this question. Society

members at this well attended evening,

watched scientists discuss what they seeas the problems with the Big Bang the-ory. The difficulty with the Big Bang isthat it's all effect and no cause, every-thing from nothing, which is philosophi-cally difficult and mathematically prob-lematic too.

Some scientists believe that the Big Bangwas not really the beginning. Our Uni-

verse may have had a life before this.This documentary explores the latestideas about the Big Bang and what cre-ated it or came before it. Theories aboutcosmic bounces, rips and multiple uni-verses are discussed to try find out whathappened before the Big Bang

The film spent much time discussing theidea of multiple Big Bangs. Neil Turok,Director of Perimeter Institute for Theo-

retical Physics in Canada, working withPaul Steinhardt at Princeton, proposes aradical new answer. Instead of the Uni-verse inexplicably springing into existencefrom a mysterious initial singularity, theBig Bang was a collision between twouniverses like ours, existing as parallelmembranes floating in a higher-dimensional space that were not awareof.

One bang is followed by another, in apotentially endless series of cosmic cy-cles, each one spelling the end of a uni-verse and the beginning of a new one.

Not one bang, but many.

Renowned English mathematical physi-cist, Sir Roger Penrose, has changed hismind about the Big Bang. He now imag-ines an eternal cycle of expanding uni-verses where matter becomes energyand back again in the birth of new uni-verses.

He now thinks that when the Universewe know of reaches the end of its life, allthat will be left are photons (single parti-cles of light). This mass converts to en-ergy creating an energised vacuum. At

this point in this cyclic system, notions oftime and mass disappear, leaving anendless sea of space in which anything ispossible.

The next Film Night is on Monday 19thMarch at 8.00pm at Stardome. It is Star-

gazing Live, in which Brian Cox and DaraO Briain cover a range of the latest topicson Astronomy in a colourful and some-times humorous way. Preserving the darksky from light intrusion and discoveringnew planets around other stars areamongst subjects covered by this 2012film. It is 50 minutes long.

It will be followed by Ocean Origins,

which is a brief, but highly colourful filmshowing how life first appeared on Earthand diversified after the first bacteriaappeared until the first vertebrateemerged onto dry land. It has some ex-ceptional photography and is 40 minuteslong.

Neil Turok, Director of Perimeter Insti-

tute for Theoretical Physics.

Sir Roger Penrose now thinks there is

an eternal cycle of universes.
http://www.starlight2012.org/http://en.wikipedia.org/wiki/English_peoplehttp://en.wikipedia.org/wiki/Mathematical_physicisthttp://en.wikipedia.org/wiki/Mathematical_physicisthttp://en.wikipedia.org/wiki/Mathematical_physicisthttp://en.wikipedia.org/wiki/Mathematical_physicisthttp://en.wikipedia.org/wiki/Mathematical_physicisthttp://en.wikipedia.org/wiki/Mathematical_physicisthttp://en.wikipedia.org/wiki/English_peoplehttp://www.starlight2012.org/


14/20


Extrasolar PlanetsA ReviewBy Bernie BrennerA

s of the 16th September 2011, there have been 684 extra-solar planets documented (Schneider 2011). By the time this

review is published, there will no doubt have been a few more

discovered. Most have been detected by radial velocity or as-trometry and smaller number by microlensing, imaging or tim-ing. Since the discovery of the very first extra-solar planet in1995 to date, the increase in the rate of discovery is exponential.Sourced from different references (Beichman, Fridlund et al.2006), (Jones 2008), (Schneider 2011), and (Udry and Santos2007) and then plotting time in months against number of plan-ets, this exponential rise is graphically depicted in fig. 1.

This review will explore the properties of extra-solar planets, thechances of finding life on them and if so, what type of life may itbe and what challenges would it face.

Properties of extra-solar planetsThe properties of extra-solar planets like radius, mass and densityis important, because it helps to determine the type of theplanet, e.g. whether it has rocks, gas, ice any or all of theabove. It also alludes to its habitability.

MassesMost of the extra-solar planets have been discovered by Doppler

radial velocity studies. This technique only provides informationabout orbital parameters and their minimum masses (Udry andSantos 2007). Sometimes the minimum mass will actually equalthe actual mass, but depending on the inclination, the actualmass can be 1.3 times the minimum mass and in the majority ofcases the actual mass will be less than twice the minimum (Jones2008).The fact that most of the extra-solar planets so far found havemasses the same or bigger than Jupiter may be the result of thecurrent state of our technology. The range extends up to 16times that of Jupiter but there may be many more smaller plan-ets (Impey 2007).To date the lowest mass planet discovered is around 3.6 timesthe mass of Earth (Cowing 2011). In general, a planet with a

mass similar to the Earth and up to ten times its mass are calledsuper-Earths.The higher end of the extra-solar planets are around 13 Jupitermasses. If they have masses like 80mJ then they are called browndwarfs. However, it is only likely that extra-solar planets withmasses < 0.03mJ will be habitable. It has been noted that many

large planets are in very small orbits they probably formedfurther out but have migrated inwards and have continued togrow in size (Jones 2008).

Using the most up to date data available for radial velocity stud-ies (Schneider 2011), we can plot the number of planets vs. m Jand this is seen in fig. 2.

SizesA planets radius can be estimated from its mass if a value of itsdensity is assumed (Beichman, Fridlund et al. 2006). Actualplanet radii are only known from transiting planets.

Using Jupiter as a standard and data from transiting planets, wenote that there is a range of ~0.1 to 2.05R J with the majorityfalling into the 1 to 1.5 range (Schneider 2011). If we plotplanet radius vs. planet mass, we can depict this graphically infig. 3.

DensitiesThe mean density of a planet is calculated by

m/[(4/3)r3]

So by knowing the mass and the radius of a planet, we cancalculate the density in the above equation.Jupiter has a mean density of 1330 kg m-3, while Earth has adensity of 5520 kg m-3. Saturn has a mean density 687 kg m-3,Neptune 1638 kg m-3 and Uranus 1270 kg m-3. Density of

Fig 1 Discovery of Exoplanets

-100

0

100

200

300

400

500

600

700

800

0 50 100 150 200

Months

NumberExoplanets

Number


15/20


some extra-solar planets can be calculated through both radialvelocity and transit photometry and those that have a massrange of between 0.33 and 1.33mJ demonstrate a mean densityof 300 to 1500 kg m-3. Where mass and radius cannot be deter-mined, the density can be assumed based on relative mass com-pared to Earth. So for cases >50mE, the densities are betweenJupiter and Saturn. For the range between 10 and 50mE, thedensities are between Uranus and Neptune. For


16/20


Stardate 2012By Gavin Logan

President GrantChristie (021)02404992

VicePresident DavidBritten (09)8463657

Treasurer& AndrewBuckingham (09)4735877

Membership

Secretary KleoZois 0226912055

Curatorof IvanVazey (09)5353987

Instruments

Librarian TonyReynolds (09)4808607

JournalEditors CliveBolt (09)5342946

ShaunFletcher (09)4805648

MilinaRisti (029)9124748

Webmaster NickMoore (09)5371500

Council GavinLogan (09)8206001

Council BernieBrenner (09)4453293

The 2011 Council

AucklandAstronomicalSocietyInc,

POBox24187,RoyalOak,Auckland1345,NewZealand

Email [email protected]

Journal [email protected]

Website www.astronomy.org.nz

MembershipinquiriescontactAndrewBuckinghamattreasurer@astronomy.org.nzor

byphoneon(09)4735877orbymobileon0272462446

Society Contacts

Stardate 2012 took place atTukitiki just outside Hastings on

January 20th to 22nd. It is a three day

dark sky weekend, organised by thePhoenix Astronomical Society, whichis held annually, with talks on variousscientific topics during the day andearly evening and telescope viewingat night (weather permitting).This year only provided one perfectlyclear night and that was on theopening Friday, during which an ar-ray of different types of telescopeswere available to look through fromvery large Dobsonian reflectors to aspecialised Ritchey-Chrtien tele-

scope.On the Saturday morning there was atelescope trail in which all theequipment was on display and theowners of each telescope told theattendees about it.

Lectures topics ranged from Ultravio-let Irradiation and Skin Lesions (SkinCancer), Hydrogen Alpha Observa-tions and Photography to Cook andthe Transit of Venus in 1769 and

2012. Of particular interest to theauthor was an astrophotographyworkshop which gave practical dem-onstrations of how to process deepsky photos.

Stephen Chadwick giving a talk on Hydrogen Alpha

imaging of the Sun.

Ivan Vasey Curator of Instruments for the Auckland As-

tronomical Society telling people on the telescope trail

about the GSO Ritchey-Chretien Astrograph telescope

sold by Astronz. Telescopes, telescopes and telescopes!


17/20


Chart produced by Guide 8 software; www.projectpluto.com. Labels and text added by Alan Gilmore, Mt John Observatory of the

University of Canterbury.www.canterbury.ac.nz

TheNightSkyinMarch2012

FromtheRASNZWebsite

To use the chart, hold it up to the sky. Turn the chart so thedirection you are looking is at the bottom of the chart. If you arelooking to the south then have 'South horizon' at the loweredge. As the Earth turns the sky appears to rotate clockwisearound the south celestial pole (SCP on the chart). Stars rise inthe east and set in the west, just like the Sun. The sky makes asmall extra rotation from night to night as we orbit the Sun.

Four planets grace the evening sky. The brightest are Venus andJupiter, low in the west at dusk. They see early. Mars is the

bright orange-red 'star' in the northeast. Medium bright Saturnis the lower 'star' of a similar pair in the east. Sirius is thebrightest star, northwest of overhead. Canopus, the secondbrightest star, is southwest of overhead. Orion, containing 'ThePot', is below Sirius in the northwest sky with Taurus and thePleiades/Matariki cluster lower again. The Southern Cross andPointers are midway up the southeast sky. Nearby galaxies, the

Clouds of Magellan, LMC and SMC, are high in the south sky.The Scorpion rises in the southeast later.


18/20


ObservingNotesMarch2012

ByAlanGilmoreF

our planets enliven the early evening sky. Venus and Jupiter make an eye-catching pair low in the western twilight. They set asthe sky darkens. Venus is the brighter of the two. At the beginning of the month it is lower than Jupiter. Venus keeps much the

same angle from the Sun, setting around two hours after the Sun through March and April. Jupiter slips steadily lower as we move tothe far side of the Sun from it. It passes to the left of Venus at mid month. In a telescope Venus looks like a first-quarter Moon. Jupi-ter shows a disk with its four bright 'Galilean' moons lined up on either side. Jupiter is 840 million km from us in March. Venus is 120million km away mid-month.

Mars is mid-way up the northeast sky, shining with a reddish-orange light. We pass closest to it at the beginning of March. This'closest' is much further away than the best, though. On March 5 Mars will be 101 million km from us. A telescope will show it as asmall disk one-third as big as Jupiter. Mars appears to move westward, leftward, against the background stars as we pass it by.

Saturn is in the east at dusk. It is a little brighter than Spica the brightest star in Virgo, above Saturn. A telescope magnifying 20xshows Saturn's rings. Its largest moon, Titan, is four ring-diameters from the planet. Saturn is 1330 million km away in mid March.

Sirius is the brightest star in the sky though fainter than planets Venus and Jupiter. It appears at dusk, northwest of overhead. It isquickly followed by Canopus, southwest of the zenith. Below Sirius are Rigel and Betelgeuse, the brightest stars in Orion. Betweenthem is a line of three stars: Orion's belt. To southern hemisphere star watchers, the line of three makes the bottom of 'The Pot'.Orion's belt points down and left to a V-shaped pattern of stars making the face of Taurus the Bull. Further down and left, low in thenorthwest, is the Pleiades or Matariki star cluster, setting early.Sirius is the brightest star in the sky both because it is relatively close, nine light years* away, and 23 times brighter than the Sun.Rigel, above and left of Orion's belt, is a bluish supergiant star,40 000 times brighter than the Sun and much hotter. It is 800 light years away. Orange Betelgeuse, below and right of the line ofthree, is a red-giant star, cooler than the Sun but much bigger and 9000 times brighter. It is 400 light years from us. The handle of"The Pot", or Orion's sword, has the Orion Nebula at its centre; a glowing gas cloud many light-years across and 1300 light years

away.

Near the north skyline are Pollux and Castor marking the heads of Gemini the twins. Right of them and higher is the star clusterPraesepe, marking the shell of Cancer the crab. Praesepe is also called the Beehive cluster, the reason obvious when it is viewed inbinoculars. It is 500 light years away. Young clusters, like the Pleiades/Matariki cluster have bright stars in them. The bright stars burnout after a 100 million years or so. Old clusters like Praesepe have no bright stars.

Crux, the Southern Cross, is in the southeast. Below it are Beta and Alpha Centauri, often called 'The Pointers'. Alpha Centauri is theclosest naked-eye star, 4.3 light years away. Beta Centauri, like most of the stars in Crux, is a blue-giant star hundreds of light yearsaway. Canopus is also a very luminous distant star; 13 000 times brighter than the Sun and 300 light years away.The Milky Way is brightest in the southeast toward Crux. It becomes broader lower in the southeast toward Scorpius. Above Crux theMilky Way can be traced to nearly overhead where it fades. It becomes very faint in the north, right of Orion. The Milky Way is ouredgewise view of the galaxy, the pancake of billions of stars of which the Sun is just one.

The Clouds of Magellan, LMC and SMC are high in the south sky, easily seen by eye on a dark moonless night. They are two smallgalaxies about 160 000 and 200 000 light years away.

*A light year (l.y.)is the distance that light travels in one year: nearly 10 million million km or 1013 km. Sunlight takes eight minutes toget here; moonlight about one second. Sunlight reaches Neptune, the outermost major planet, in four hours. It takes four years toreach the nearest star, Alpha Centauri.

SocietyTelescopesForHireTheSocietyhasawiderangeoftelescopesforhiretomembers.

Ifyouare looking topurchaseorupgradea telescopeandarenotsurewhattobuy,thisisaverygoodwaytoevaluatesomeoftheavailableequipment.Seealsotheadvertisementonthebackpage.

To

inquire

about

hiring

or

for

advice

on

what

to

buy

and

for

information about equipment, contact Ivan Vazey, curator ofinstruments,[email protected](09)5353987


19/20


NotesbyAlanGilmore,UniversityofCanterbury'sMtJohnObservatory,P.O.Box56,LakeTekapo7945,NewZealand.www.canterbury.ac.nz

DiaryofSolarSystemEventsforMarch2012

FromtheRASNZWebsiteDate(NZDT) DiaryofSolarSystemEventsinMarch2012forNewZealand

March1 Moonatfirstquarter2.21pmNZDT(1:21UT).

March2 Moonfurthestnorth,solowestsouthernhemispheretransitforthemonth.

March4 Marsatopposition9amNZDT(Mar3,20hrUT).

March5 Mercuryatgreatestelongation18eastofSun.

March6 MarsnearesttoEarth,100.78millionkmat6amNZDT(Mar5,17hrUT).

March7 98.5%litMoon6toupperrightofRegulus Leomagnitude1.4,and12toupperleftofMars,lateeveningsky.

March8 FullMoonat10.40pmNZDT(9:40UT),10toupperrightofMars.

March10 Moonatperigee,itsclosesttotheEarthforthelunarmonth,362398km,

March10 94%litMoon5.5toupperleftofSpica,magnitude1.1,lateeveningsky.

March11 87%litMoon7torightofSaturn,lateeveningsky.

March12 Mercurystationary.

March14 65%litMoon6belowAntares, Scorpii,magnitude1.1,earlydawnsky.

March14 Venus3belowandslightlyrightofJupiter,earlyeveningsky.

March15 Moonfurthestsouth,sohighestsouthernhemispheretransitforthemonth.

March15 Moonatlastquarter2.25pmNZDT(1:25UT).

March20 SouthernAutumnEquinox,Sunonequatorat6.15pmNZDT.

March22 Mercuryatinferiorconjunction.

March23 NewMoonat3.37amNZDT(Mar22,14:37UT).

March25 UranusinconjunctionwiththeSun.

March26 Moonatapogee,itsgreatestdistancefromtheEarthfortheLunarmonth,405780km.

March26 12%litMoon5.5torightofJupiterand5.8toleftofVenus,earlyeveningsky.

March27 Venusatgreatestelongation,46eastofSun.

March27 19%litMoon5.3torightofVenusand3toupperleftofPleiadesstarcluster,lowearlyeveningsky.

March28 27%litMoon6belowAldebaran, Tauri,eveningsky.

March29 Moonfurthestnorth,solowestsouthernhemispheretransitforthemonth.

March31 Moonatfirstquarter8.41amNZDT(Mar30,19:41UT).


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aas journal march 2012

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