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Space News Update — November 30, 2018 —

Contents

In the News

Story 1: Hubble uncovers thousands of globular star clusters scattered among

galaxies

Story 2: NASA selects nine companies for commercial lunar lander program

Story 3: Fermi Traces the History of Starlight Across the Cosmos

Departments

The Night Sky

ISS Sighting Opportunities

Space Calendar

NASA-TV Highlights

Food for Thought

Space Image of the Week

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1. Hubble uncovers thousands of globular star clusters scattered among galaxies

Gazing across 300 million light-years into a monstrous city of galaxies, astronomers have used NASA's Hubble Space Telescope to do a comprehensive census of some of its most diminutive members: a whopping 22,426 globular star clusters found to date.

The survey, published in the November 9, 2018, issue of The Astrophysical Journal, will allow for astronomers to use the globular cluster field to map the distribution of matter and dark matter in the Coma galaxy cluster, which holds over 1,000 galaxies that are packed together.

Because globular clusters are much smaller than entire galaxies – and much more abundant – they are a much better tracer of how the fabric of space is distorted by the Coma cluster's gravity. In fact, the Coma cluster is one of the first places where observed gravitational anomalies were considered to be indicative of a lot of unseen mass in the universe – later to be called "dark matter."

Among the earliest homesteaders of the universe, globular star clusters are snow-globe-shaped islands of several hundred thousand ancient stars. They are integral to the birth and growth of a galaxy. About 150 globular clusters zip around our Milky Way galaxy, and, because they contain the oldest known stars in the universe, were present in the early formative years of our galaxy.

Some of the Milky Way's globular clusters are visible to the naked eye as fuzzy-looking "stars." But at the distance of the Coma cluster, its globulars appear as dots of light even to Hubble's super-sharp vision. The survey found the globular clusters scattered in the space between the galaxies. They have been orphaned from their home galaxy due to galaxy near-collisions inside the traffic-jammed cluster. Hubble revealed that some globular clusters line up along bridge-like patterns. This is telltale evidence for interactions between galaxies where they gravitationally tug on each other like pulling taffy.

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Astronomer Juan Madrid of the Australian Telescope National Facility in Sydney, Australia first thought about the distribution of globular clusters in Coma when he was examining Hubble images that show the globular clusters extending all the way to the edge of any given photograph of galaxies in the Coma cluster.

He was looking forward to more data from one of the legacy surveys of Hubble that was designed to obtain data of the entire Coma cluster, called the Coma Cluster Treasury Survey. However, halfway through the program, in 2006, Hubble's powerful Advanced Camera for Surveys (ACS) had an electronics failure. (The ACS was later repaired by astronauts during a 2009 Hubble servicing mission.)

To fill in the survey gaps, Madrid and his team painstakingly pulled numerous Hubble images of the galaxy cluster taken from different Hubble observing programs. These are stored in the Space Telescope Science Institute's Mikulski Archive for Space Telescopes in Baltimore, Maryland. He assembled a mosaic of the central region of the cluster, working with students from the National Science Foundation's Research Experience for Undergraduates program. "This program gives an opportunity to students enrolled in universities with little or no astronomy to gain experience in the field," Madrid said.

The team developed algorithms to sift through the Coma mosaic images that contain at least 100,000 potential sources. The program used globular clusters' color (dominated by the glow of aging red stars) and spherical shape to eliminate extraneous objects – mostly background galaxies unassociated with the Coma cluster.

Though Hubble has superb detectors with unmatched sensitivity and resolution, their main drawback is that they have tiny fields of view. "One of the cool aspects of our research is that it showcases the amazing science that will be possible with NASA's planned Wide Field Infrared Survey Telescope (WFIRST) that will have a much larger field of view than Hubble," said Madrid. "We will be able to image entire galaxy clusters at once."

Source: Phys.org Return to Contents

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2. NASA selects nine companies for commercial lunar lander program

Lockheed Martin said it w ill offer the McCandless Lunar Lander, based on its designs for Mars landers, under its Commercial Lunar Payload Services award announced by NASA Nov. 29. Credit: Lockheed Martin

NASA has picked nine companies, ranging from startups to aerospace giants, to be eligible for future contracts to deliver payloads to the surface of the moon, but with no guarantee of business for any of them.

NASA announced Nov. 29 the selections as part of its Commercial Lunar Payload Services (CLPS) program, where the agency will buy space on future commercial lunar landers to carry science instruments and other payloads. The winning companies are:

• Astrobotic Technology, Inc.: Pittsburgh • Deep Space Systems: Littleton, Colorado • Draper: Cambridge, Massachusetts • Firefly Aerospace, Inc.: Cedar Park, Texas • Intuitive Machines, LLC: Houston • Lockheed Martin Space: Littleton, Colorado • Masten Space Systems, Inc.: Mojave, California • Moon Express: Cape Canaveral, Florida • Orbit Beyond: Edison, New Jersey

The companies selected range from a major aerospace corporation, Lockheed Martin, to little-known startups, and from companies that were longtime competitors in the now-expired Google Lunar X Prize for commercial lunar landers to those that had not previously publicly expressed plans for such landers.

“When we go to the moon, we want to be one customer of many customers in a robust marketplace between the Earth and the moon,” NASA Administrator Jim Bridenstine said during an event at NASA Headquarters to announce the selections. “We want multiple providers that are competing on cost and innovation.”

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In the press release announcing the winning companies, NASA said the companies are eligible for up to $2.6 billion in awards over the next ten years. The agency didn’t disclose the maximum contract amounts for each company. The awards are all indefinite delivery, indefinite quantity contracts, and it’s not unusual for the actual value of such awards to be far less than the maximum value.

For now, each company will receive a small, unspecified amount of funding to develop a payload users’ guide. NASA will later compete individual task orders among the companies to fly specific payloads to the moon.

“They are becoming part of the catalog, so to say,” said Thomas Zurbuchen, NASA associate administrator for science. “They will compete for tasks that we’re going to put out there weeks and months from now.” The first missions under CLPS could take place in 2019, NASA said in its announcement, although many industry sources expect 2020 to be a more reasonable date for a first mission under the program.

NASA is in the process of identifying payloads that could fly on those payloads. Zurbuchen said the agency has a “set of instruments” that are either ready for flight now or could be ready in the near future, such as a retroreflector to enable accurate laser ranging of the Earth-moon distance. NASA also issued in October a call for instruments and other technologies that can be flown on commercial landers.

NASA is providing no development money for any of the CLPS companies, who will have to raise the funding needed for their landers from other sources. Both Bridenstine and Zurbuchen acknowledged that some of the winners might not be able to deliver on their landers, while new companies may emerge that could be eligible to join the program through future “on-ramps.”

“Think of it like venture capital. Our investment is low because we have other people who are investing,” said Bridenstine. “But we have more providers. In other words, the portfolio is larger, so we can take risk.”

The companies themselves made only a cameo appearance at the event, briefly appearing on stage but making no remarks. Afterwards some of the companies discussed details about their planned lander systems.

Lockheed Martin, by far the largest company selected for CLPS, said it will develop what it called the McCandless Lunar Lander, named after the late astronaut Bruce McCandless. The lander is based on designs for Martian landers the company produced for NASA, including the InSight lander that touched down on Mars Nov. 26.

“Lockheed’s lander is a little bit larger than some of the others,” said Joe Landon, vice president of advanced program development at Lockheed Martin’s commercial civil space unit. He said the lander will be able to deliver payloads of up to 100 kilograms.

Near the other end of the corporate spectrum is Orbit Beyond, a small company with plans to develop a series of lunar landers. It is teamed on its CLPS award with several other companies, including Team Indus, one of the finalists in the Google Lunar X Prize. Team Indus, based in Bangalore, India, is not eligible itself for a CLPS award because of NASA requirements that companies be based in the United States, with development work done domestically.

Jeff Patton, chief engineering advisor for Orbit Beyond, said the company will transfer the technology for Team Indus’ lander so that versions of it can be built in the U.S., with the company looking at potential facilities in the Cape Canaveral, Florida, area for integration and testing. “The design is really mature now,” he said.

Masten Space Systems is developing a lunar lander called XL-1 that will be able to place up to 100 kilograms on the lunar surface starting in 2021. Sean Mahoney, chief executive of Masten, called the award a long-awaited milestone for the company, which won part of the Northrop Grumman Lunar Lander Challenge, part of NASA’s Centennial Challenges prize program, nearly a decade ago.

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“Going from 2009 and the Lunar Lander Challenge to today, we’ve been working for this thing to exist,” he said of CLPS.

He noted that many of the specifics of how CLPS will work have yet to be determined, but he was optimistic about its prospects. “A lot of this is still developing, but the good news is that it’s moving quickly.”

Source: Space News Return to Contents

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3. Fermi Traces the History of Starlight Across the Cosmos

Scientists using data from NASA's Fermi Gamma-ray Space Telescope have measured all the starlight produced over 90 percent of the universe's history.

The analysis, which examines the gamma-ray output of distant galaxies, estimates the formation rate of stars and provides a reference for future missions that will explore the still-murky early days of stellar evolution.

"Stars create most of the light we see and synthesize most of the universe's heavy elements, like silicon and iron," said lead scientist Marco Ajello, an astrophysicist at Clemson University in South Carolina. "Understanding how the cosmos we live in came to be depends in large part on understanding how stars evolved."

A paper describing the new starlight measurement appears in the Nov. 30 issue of Science and is now available online.

One of the main goals of the Fermi mission, which celebrated its 10th anniversary in orbit this year, was to assess the extragalactic background light (EBL), a cosmic fog composed of all the ultraviolet, visible and infrared light stars have created over the universe's history. Because starlight continues to travel across the cosmos long after its sources have burned out, measuring the EBL allows astronomers to study stellar formation and evolution separately from the stars themselves.

"This is an independent confirmation of previous measurements of star-formation rates," said David Thompson, Fermi's deputy project scientist at NASA's Goddard Space Flight Center in Greenbelt, Maryland. "In astronomy, when two completely independent methods give the same answer, that usually means we're doing something right. In this case we're measuring star formation without looking at stars at all but by observing gamma rays that have traveled across the cosmos."

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Gamma rays are the highest-energy form of light. They are so energetic, in fact, that their interactions with starlight have unusual consequences. "When the right frequencies of light collide, they can convert into matter through Albert Einstein's famous equation E=mc2," said co-author Alberto Dominguez, an astrophysicist at Complutense University of Madrid.

The collision between a high-energy gamma ray and infrared light, for example, transforms the energy into a pair of particles, an electron and its antimatter counterpart, a positron. The same process occurs when medium-energy gamma rays interact with visible light, and low-energy gamma rays interact with ultraviolet light. Fermi's ability to detect gamma rays across a wide range of energies makes it uniquely suited for mapping the EBL spectrum. Enough of these interactions occur over cosmic distances that the farther back scientists look, the more evident their effects become on gamma-ray sources, enabling a deep probe of the universe's stellar content.

The scientists, led by Vaidehi Paliya, a postdoctoral researcher in Ajello's group at Clemson, examined gamma-ray signals from 739 blazars -- galaxies with monster black holes at their centers -- collected over nine years by Fermi's Large Area Telescope (LAT). The measurement quintuples the number of blazars used in an earlier Fermi EBL analysis published in 2012 and includes new calculations of how the EBL builds over time, revealing the peak of star formation around 10 billion years ago.

The new EBL measurement also provides important confirmation of previous estimates of star formation from missions that analyze many individual sources in deep galaxy surveys, like the Hubble Space Telescope. These types of surveys, however, often miss fainter stars and galaxies and cannot account for star formation that takes place in intergalactic space. These missing contributions must be estimated during each survey's analysis.

The EBL, though, includes starlight from all sources and avoids these problems. The Fermi result therefore provides independent confirmation that measurements using deep galaxy surveys properly account for their biases. It can also help guide future surveys from missions like the James Webb Space Telescope (JWST).

"One of Webb's primary objectives is to unravel what happened in the first billion years after the big bang," said co-author Kári Helgason, an astrophysicist at the University of Iceland. "Our work places important new limits on the amount of starlight we can expect to see in those first billion years -- a largely unexplored epoch in the universe -- and provides a benchmark for future studies."

Source: SpaceRef.com Return to Contents

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The Night Sky Friday, November 30

• Two faint fuzzies naked-eye:The Andromeda Galaxy (M31) and the Perseus Double Cluster are two of the most famous deep-sky objects. They're both cataloged as 4th magnitude, and in a fairly good sky you can see each with the unaided eye. They're only 22° apart, very high toward the east early these evenings — to the right of Cassiopeia and closer below Cassiopeia, respectively.

Saturday, December 1

• Vega still shines brightly in the west-northwest after dark. The brightest star above it is Deneb, the head of the big Northern Cross, which is made of the brightest stars of Cygnus. At nightfall the shaft of the cross extends lower left from Deneb (by about two fists at arm's length). By about 11 or midnight, it plants itself more or less upright on the northwest horizon.

Sunday, December 2

• Algol should be at its minimum brightness, magnitude 3.4 instead of its usual 2.1, for a couple hours centered on 9:53 p.m. EST. Algol takes several additional hours to fade and to rebrighten.

• Look southeast just as dawn begins tomorrow (about 90 minutes before your local sunrise), and there will be Venus just a few degrees below the waning crescent Moon. Look to their right for Spica, much fainter, before dawn grows too bright.

Monday, December 3

• As dawn begins tomorrow morning the 4th, the crescent Moon, Venus, and Spica form a gently curving arc low in the east, in that order upper right from the Moon. High to their upper left is Arcturus.

Tuesday, December 4

• At this time of year the Big Dipper lies down lowest soon after dark, due north. It's entirely below the north horizon if you're as far south as Miami. But by midnight, the Dipper is standing straight up on its handle in fine view in the northeast.

• Meanwhile, high above, the bowl of the Little Dipper is descending in the evening, lower left of Polaris. By 10 or 11 p.m. it hangs straight down from Polaris.

Source: Sky & Telescope Return to Contents

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ISS Sighting Opportunities

For Denver:

Date Visible Max Height Appears Disappears

Fri Nov 30, 5:52 PM 3 min 14° 10° above NW 11° above N

Sat Dec 1, 4:59 PM 5 min 18° 10° above WNW 10° above NNE

Sun Dec 2, 5:46 PM 2 min 11° 10° above NNW 10° above N

Tue Dec 4, 5:39 PM < 1 min 10° 10° above N 10° above N Sighting information for other cities can be found at NASA’s Satellite Sighting Information NASA-TV Highlights (all times Eastern Daylight Time) December 1, Saturday 12 p.m. - Video File of the International Space Station Expedition 58/Soyuz MS-11 Rollout to the Launch Pad, including interviews at the Baikonur Cosmodrome in Kazakhstan and other crew activities via Baikonur, Kazakhstan (Media Channel)

December 2, Sunday 3 p.m. – Replay of the Russian State Commission Meeting and Final Space Station Expedition 58 Pre-Launch Crew News Conference in Baikonur, Kazakhstan (All Channels)

December 3, Monday 5:30 a.m. - International Space Station Expedition 58/Soyuz MS-11 Launch Coverage, includes video B-roll of the crew’s launch day pre-launch activities at 5:45 a.m. ET; launch scheduled at 6:31 a.m. ET via Baikonur, Kazakhstan (All Channels) 9:30 a.m. - SpaceX CRS-16 What’s On Board – Kennedy Space Center (Public Channel) 9:30 a.m. - Video File of International Space Station Expedition 58/Soyuz MS-11 Pre-Launch and Launch Video and Post-Launch Interviews via Baikonur, Kazakhstan (Media Channel) 11:15 a.m. – OSIRIS-REx’s Journey to Asteroid Bennu (All Channels) 11:45 a.m. – LIVE Coverage: OSIRIS-REx Arrival at Bennu (Public Channel) 11:45 a.m. - Coverage of the Expedition 58/Soyuz MS-11 Docking to the International Space Station; docking scheduled at 12:36 p.m. (Media Channel) 12:15 p.m. - Expedition 58/Soyuz MS-11 Docking to the International Space Station; docking scheduled at 12:36 p.m. ET (All Channels) 1:45 p.m. - International Space Station Expedition 58/Soyuz MS-11 Hatch Opening and Welcoming Ceremony; hatch opening scheduled at approximately 2:35 p.m. ET (time is subject to change) via Baikonur, Kazakhstan (All Channels) 3:30 p.m. - SpaceX CRS-16 Pre-launch News Conference (All Channels) 5 p.m. - Video File of International Space Station Expedition 57-58/Soyuz MS-10 Docking, Hatch Opening and Other Activities (Media Channel)

December 4, Tuesday 1 p.m. - SpaceX CRS-16 Launch Coverage (launch at 1:38 p.m.) (All Channels) 3:30 p.m. – SpaceX CRS-16 Post-Launch News Conference (All Channels)

Watch NASA TV on the Net by going to the NASA website. Return to Contents

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Space Calendar • Nov 30 - Comet 73P-BL/Schwassmann-Wachmann At Opposition (3.562 AU) • Nov 30 - Comet 73P-AQ/Schwassmann-Wachmann At Opposition (3.584 AU) • Nov 30 - Comet 73P-AG/Schwassmann-Wachmann At Opposition (3.587 AU) • Nov 30 - Comet 73P-AR/Schwassmann-Wachmann At Opposition (3.587 AU) • Nov 30 - Amor Asteroid 2018 VE4 Near-Earth Flyby (0.039 AU) • Nov 30 - Amor Asteroid 2018 WL Near-Earth Flyby (0.081 AU) • Nov 30 - Amor Asteroid 2018 VW5 Near-Earth Flyby (0.084 AU) • Nov 30 - Aten Asteroid 2008 WT62 Near-Earth Flyby (0.087 AU) • Nov 30 - Apollo Asteroid 428694 Saule Closest Approach To Earth (0.498 AU) • Nov 30 - Asteroid 128 Nemesis Closest Approach To Earth (1.519 AU) • Nov 30 - Asteroid 2864 Soderblom Closest Approach To Earth (1.651 AU) • Nov 30 - Asteroid 37683 Gustaveeiffel Closest Approach To Earth (1.740 AU)

• Dec 01 - [Nov 28] SSO-A/ SkySat 14 & 15/ Eu:CROPIS/ STPSat 5/ FalconSat 6/ NEXTSat 1/ KazSTSAT/ eXCITe (PTB 1)/ SeeMe/ BlackSky Global 2/ HawkEye Pathfinder 1-3/ ORS 7A & 7B (Polar Scout 1 & 2)/ COPPER 2/ MinXSS 2/ Audacy Zero/ Fox 1C (Fox 1Cliff)/KNACKSAT/ Elysium-Star 2/ JY1-Sat Falcon 9 Launch

• Dec 01 - Comet 258P/PANSTARRS At Opposition (3.137 AU) • Dec 01 - Comet 89P/Russell At Opposition (3.487 AU) • Dec 01 - Comet 73P-P/Schwassmann-Wachmann At Opposition (3.602 AU) • Dec 01 - Comet 73P-AC/Schwassmann-Wachmann At Opposition (3.614 AU) • Dec 01 - Apollo Asteroid 2018 WN Near-Earth Flyby (0.038 AU) • Dec 01 - Apollo Asteroid 2018 WW Near-Earth Flyby (0.084 AU) • Dec 01 - Apollo Asteroid 2012 MM11 Near-Earth Flyby (0.086 AU) • Dec 01 - Apollo Asteroid 10563 Izhdubar Closest Approach To Earth (1.131 AU) • Dec 01 - Asteroid 3656 Hemingway Closest Approach To Earth (1.525 AU) • Dec 01 - Apollo Asteroid 314082 Dryope Closest Approach To Earth (1.923 AU) • Dec 01 - Asteroid 2688 Halley Closest Approach To Earth (2.548 AU) • Dec 01 - Kuiper Belt Object 145453 (2005 RR43) At Opposition (38.694 AU) • Dec 01 - Earth Science Educators Workshop, Pasadena, California • Dec 01 - 5th Anniversary (2013), Chang'e 3 Launch (China Moon Lander & Rover • Dec 01 - 235th Anniversary (1783), 1st Manned Hydrogen Balloon Flight • Dec 01 - Martin Klaproth's 275th Birthday (1743) • Dec 02 - Comet 267P/LONEOS At Opposition (0.945 AU) • Dec 02 - Comet 247P/LINEAR Perihelion (1.489 AU) • Dec 02 - Comet C/2018 L2 (ATLAS) Perihelion (1.712 AU) • Dec 02 - Comet 73P-X/Schwassmann-Wachmann At Opposition (3.647 AU) • Dec 02 - Comet 73P-L/Schwassmann-Wachmann At Opposition (3.648 AU) • Dec 02 - Comet 73P-AN/Schwassmann-Wachmann At Opposition (3.649 AU) • Dec 02 - Comet 73P-AH/Schwassmann-Wachmann At Opposition (3.651 AU) • Dec 02 - Comet 73P-Z/Schwassmann-Wachmann At Opposition (3.666 AU) • Dec 02 - Comet 73P-AO/Schwassmann-Wachmann At Opposition (3.668 AU) • Dec 02 - Apollo Asteroid 2018 TG6 Near-Earth Flyby (0.010 AU) • Dec 02 - Asteroid 990 Yerkes Closest Approach To Earth (1.428 AU) • Dec 02 - Asteroid 3895 Earhart Closest Approach To Earth (1.489 AU) • Dec 02 - Asteroid 13212 Jayleno Closest Approach To Earth (1.874 AU) • Dec 02 - Asteroid 8103 Fermi Closest Approach To Earth (2.109 AU) • Dec 02 - Asteroid 11020 Orwell Closest Approach To Earth (2.451 AU) • Dec 02 - Kuiper Belt Object 2006 QH181 At Opposition (83.021 AU)

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• Dec 02 - 25th Anniversary (1993), STS-61 Launch (Space Shuttle Endeavour, Hubble Space Telescope Servicing)

• Dec 02 - 30th Anniversary (1988), STS-27 Launch (Space Shuttle Atlantis, DOD)

• Dec 03 - [Nov 27] Soyuz MS-11 Soyuz-FG Launch (International Space Station 57S)

• Dec 03 - [Nov 27] OSIRIS-REx, Asteroid Bennu Arrival • Dec 03 - Comet C/2018 V1 (Machholz-Fujikawa-Iwamoto) Perihelion (0.387 AU) • Dec 03 - Comet 300P/Catalina Closest Approach To Earth (1.041 AU) • Dec 03 - Comet 73P-R/Schwassmann-Wachmann At Opposition (3.681 AU) • Dec 03 - Comet 73P-M/Schwassmann-Wachmann At Opposition (3.688 AU) • Dec 03 - Comet 73P-AD/Schwassmann-Wachmann At Opposition (3.689 AU) • Dec 03 - Comet 73P-E/Schwassmann-Wachmann At Opposition (3.692 AU) • Dec 03 - Comet 73P-K/Schwassmann-Wachmann At Opposition (3.702 AU) • Dec 03 - Comet 73P-H/Schwassmann-Wachmann At Opposition (3.703 AU) • Dec 03 - Comet 73P-B/Schwassmann-Wachmann At Opposition (3.705 AU) • Dec 03 - Comet 73P-G/Schwassmann-Wachmann At Opposition (3.709 AU) • Dec 03 - Comet 73P/Schwassmann-Wachmann At Opposition (3.711 AU) • Dec 03 - Comet 73P-C/Schwassmann-Wachmann At Opposition (3.711 AU) • Dec 03 - Comet 73P-BT/Schwassmann-Wachmann At Opposition (3.713 AU) • Dec 03 - Comet 73P-AV/Schwassmann-Wachmann At Opposition (3.716 AU) • Dec 03 - Asteroid 2952 Lilliputia Closest Approach To Earth (0.979 AU) • Dec 03 - Asteroid 757 Portlandia Closest Approach To Earth (1.139 AU) • Dec 03 - Asteroid 5190 Fry Closest Approach To Earth (1.622 AU) • Dec 03 - Kuiper Belt Object 229762 (2007 UK126) At Opposition (41.244 AU) • Dec 03 - 45th Anniversary (1973), Pioneer 10, Jupiter Flyby • Dec 03 - 60th Anniversary (1958), JPL Transferred from the Army to NASA

• Dec 04 - [Nov 29] CRS-16/ IDA 3 Falcon 9 Launch (International Space Station) • Dec 04 - GSAT 11/ GEO-KOMPSAT-2A Ariane 5 Launch • Dec 04 - Comet 359P/LONEOS At Opposition (2.991 AU) • Dec 04 - Comet 73P-AU/Schwassmann-Wachmann At Opposition (3.734 AU) • Dec 04 - Comet 73P-AK/Schwassmann-Wachmann At Opposition (3.735 AU) • Dec 04 - Comet 73P-BQ/Schwassmann-Wachmann At Opposition (3.751 AU) • Dec 04 - Comet 73P-N/Schwassmann-Wachmann At Opposition (3.755 AU) • Dec 04 - Comet C/2015 XY1 (Lemmon) Closest Approach To Earth (7.094 AU) • Dec 04 - Amor Asteroid 2018 VZ3 Near-Earth Flyby (0.061 AU) • Dec 04 - Asteroid 29470 Higgs Closest Approach To Earth (1.971 AU) • Dec 04 - Asteroid 51824 Mikeanderson Closest Approach To Earth (2.073 AU) • Dec 04 - Asteroid 8624 Kaleycuoco Closest Approach To Earth (2.281 AU) • Dec 04 - 20th Anniversary (1998), STS-88 Launch (Space Shuttle Endeavour, International Space

Station) • Dec 04 - 40th Anniversary (1978), Pioneer Venus 1, Venus Orbit Insertion

Source: JPL Space Calendar Return to Contents

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Food for Thought

Black hole 'donuts' are actually 'fountains'

Based on computer simulations and new observations from the Atacama Large Millimeter/submillimeter Array (ALMA), researchers have found that the rings of gas surrounding active supermassive black holes are not simple donut shapes. Instead, gas expelled from the center interacts with infalling gas to create a dynamic circulation pattern, similar to a water fountain in a city park.

Most galaxies host a supermassive black hole, millions or billions of times as heavy as the Sun, in their centers. Some of these black holes swallow material quite actively. But astronomers have believed that rather than falling directly into the black hole, matter instead builds up around the active black hole forming a donut structure.

Takuma Izumi, a researcher at the National Astronomical Observatory of Japan (NAOJ), led a team of astronomers that used ALMA to observe the supermassive black hole in the Circinus Galaxy located 14 million light-years away from the Earth in the direction of the constellation Circinus. The team then compared their observations to a computer simulation of gas falling towards a black hole made with the Cray XC30 ATERUI supercomputer operated by NAOJ. This comparison revealed that the presumptive "donut" is not actually a rigid structure, but instead a complex collection of highly dynamic gaseous components. First, cold molecular gas falling towards the black hole forms a disk near the plane of rotation. As it approaches the black hole, this gas is heated until the molecules break down into the component atoms and ions. Some of these atoms are then expelled above and below the disk, rather than being absorbed by the black hole. This hot atomic gas falls back onto the disk creating a turbulent three dimensional structure. These three components circulate continuously, similar to a water fountain in a city park.

"Previous theoretical models set a priori assumptions of rigid donuts," explains Keiichi Wada, a theoretician at Kagoshima University in Japan, who lead the simulation study and is a member of the research team. "Rather than starting from assumptions, our simulation started from the physical equations and showed for the first

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time that the gas circulation naturally forms a donut. Our simulation can also explain various observational features of the system."

"By investigating the motion and distribution of both the cold molecular gas and warm atomic gas with ALMA, we demonstrated the origin of the so-called 'donut' structure around active black holes," said Izumi. "Based on this discovery, we need to rewrite the astronomy textbooks."

Source: EurekAlert Return to Contents

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Space Image of the Week

Cosmic Serpent

The VISIR instrument on ESO’s VLT captured this stunning image of a newly-discovered massive binary star system. Nicknamed Apep after an ancient Egyptian deity, it could be the first gamma-ray burst progenitor to be found in our galaxy.

Apep’s stellar winds have created the dust cloud surrounding the system, which consists of a binary star with a fainter companion. With 2 Wolf-Rayet stars orbiting each other in the binary, the serpentine swirls surrounding Apep are formed by the collision of two sets of powerful stellar winds, which create the spectacular dust plumes seen in the image.

The reddish pinwheel in this image is data from the VISIR instrument on ESO’s Very Large Telescope (VLT), and shows the spectacular plumes of dust surrounding Apep. The blue sources at the centre of the image are a triple star system — which consists of a binary star system and a companion single star bound together by gravity. Though only two star-like objects are visible in the image, the lower source is in fact an unresolved binary Wolf-Rayet star. The triple star system was captured by the NACOadaptive optics instrument on the VLT.

Credit: ESO/Callingham et al. Source: ESO Return to Contents