cataclysmic variables in the aavso observing program janet a. mattei kerriann h. malatesta aavso...
TRANSCRIPT
Cataclysmic Variables in the AAVSO Observing Program
Janet A. MatteiKerriann H. Malatesta
AAVSO
Second HEA WorkshopJuly 4-5, 2002, Waikoloa Beach, Hawaii
Cataclysmic VariablesCataclysmic Variables
• Compact close binary systems
• Red dwarf-type (Sun-like) star – secondary-and a white dwarf -primary
• Due to evolution, the red star is losing matter to the white dwarf star via an accretion diskArtwork by K. Smale
The Many Faces of The Many Faces of Cataclysmic VariablesCataclysmic Variables
Other Types of Variables
82%
Cataclysmic Variables
18%
Cataclysmic Variables in the Cataclysmic Variables in the AAVSO Observing ProgramAAVSO Observing Program
Dwarf NovaeDwarf Novae
• Also known as U Geminorum stars, named for the first dwarf nova
• Close binary system• Changes in magnitude
result of processes in the disk
• Several subtypes: SS Cygni, SU Ursae Majoris, and Z Camelopardalis
Artwork by M. Garlick
SS Cygni StarsSS Cygni Stars
• Vary by 2-6 magnitudes, lasting 1-2 weeks
• Outbursts on a timescale of 10-1000 days
• Rise to maximum is fast generally <1 day
• Decline is longer, typically 2-15 days
Photographs of SS Cygni by AAVSO Chartmaker Charles Scovil
SS Cygni Long-Term Light CurveSS Cygni Long-Term Light Curve
and a closer look at SS Cyg
Wide Outburst
Narrow Outburst
SU Ursae Majoris StarsSU Ursae Majoris Stars
• Narrow outbursts of about 1-2 days
• Brighter superoutbursts of an additional 2 magnitudes lasting about 10-20 days
• Superhumps seen during superoutbursts
• Subtype:WZ Sagittae
Artwork by M. Garlick
SU UMa and SuperoutburstsSU UMa and Superoutbursts
Superoutbursts
SU UMa Subtype: WZ Sge
WZ Sge is an SU UMa star with an extremely long supercycle
An Example of SuperhumpsAn Example of Superhumps
Superhump activity of the 2001 outburst, as recorded by AAVSO observer Lew Cook (COO)
Past Outbursts of WZ SgePast Outbursts of WZ Sge
Z Camelopardalis StarsZ Camelopardalis Stars
• Similar to the SS Cygni stars, but cyclic variations interrupted by intervals of constant brightness, known as standstills
• Standstills occur approximately one-third of the way from maximum to minimum
Artwork by M. Garlick
Z Camelopardalis Long-Term Z Camelopardalis Long-Term Light CurveLight Curve
Standstill
Standstill
Z Cam and StandstillsZ Cam and Standstills
Standstill
NovaeNovae• Undergo one large
outburst due to thermo-nuclear runaway
• Amplitude may change by 8-15 magnitudes
• Rise-time to maximum and decline to minimum vary
• Subtypes: fast nova (Na), slow nova (Nb), and very slow nova (Nc)
WIYN Telescope image of the nova GK Per
Nova Light CurvesNova Light Curves
GK Persei Long-Term Light CurveGK Persei Long-Term Light Curve
Nova Outburst
Dwarf Nova-Type Outbursts
Recurrent NovaeRecurrent Novae
• Photometric and spectroscopically similar to novae
• Rapid rise to maximum• Brighten by 4-9
magnitudes• Decline faster than that
of novae• Recur every 10-100
years
HST image of the recurrent nova T Pyxidis
RS Ophiuchi Long-Term Light CurveRS Ophiuchi Long-Term Light Curve
Recurrent Nova Outburst
Nova-likeNova-like
• Similar to novae in terms of light changes and spectral features
• Subtypes: V Sagittae, UX Ursae Majoris, and VY Sculptoris
WIYN Telescope image of the nova-like variable BZ Cam
Polars (AM Her stars)Polars (AM Her stars)• White dwarf star has
magnetic field of 10-100 mega Gauss
• Accretion columns, instead of an accretion disk
• Synchronous rotation (Pspin = Porb)
• Source of hard X-ray, extreme UV, UV, as well as optical wavelengths
Artwork by R. Kightley
Anatomy of a PolarAnatomy of a Polar
Image from HEASARC
Light Curve of AM HerculisLight Curve of AM Herculis
Intermediate Polars (DQ Her Intermediate Polars (DQ Her stars)stars)
• White dwarf has magnetic field of 1-10 mega Gauss
• Accretion disk yields to accretion column near white dwarf
• Rotation not synchronous
• Source of hard X-ray, UV, as well as optical wavelengths
Artwork by R. Kightley
AAVSO Variable Star ChartsAAVSO Variable Star Charts
Old favorites
New additions
Cataclysmic Variables in the Cataclysmic Variables in the AAVSO Observing ProgramAAVSO Observing Program
0
50
100
150
200
250
Type
Novae
UG
UGSS
Nova-like
CV
UZ
UGSU
Polars
Recurrent Novae
When Good Stars MisbehaveWhen Good Stars Misbehave
SU UMa takes a superoutburst
hiatus
U Gem has a double-wide
outburst
SS Aur lacks
amplitude
Alert Notice 292
THE AMERICAN ASSOCIATION OF VARIABLE STAR OBSERVERS 25 Birch Street, Cambridge, MA 02138 USA
INTERNET: [email protected] Tel. 617-354-0484 Fax 617-354-0665
AAVSO ALERT NOTICE 292 (January 10, 2002)
0659-03 PECULIAR VARIABLE IN MONOCEROS (VAR MON 02)
We have been informed by the Central Bureau for Astronomical Telegrams (IAU Circular 7785) that Nicholas J. Brown, Quinns Rocks, W. Australia, has photographically discovered a possible nova in Monoceros on January 6.6 UT at about magnitude 10 on a T-Max 400 film. He confirmed it visually on January 7.6 UT at magnitude 10.0. Confirming observations reported via the AAVSO were: Jan. 8.094 UT, 10.1 CCDV, Charles Scovil, Stamford, CT; 9.513, 9.3 CCD, Peter Nelson, Ellinbank, Victoria, Australia; 9.815, 9.5 CCD, Arto Oksanen and Juha Solonen, Nyrola Observatory, Finland. Brown reported that nothing was visible at the location of the object down to magnitude 12 on a photograph taken 2001 December 22.
More at: http://www.aavso.org/alerts/alert292/alert292text.stm
Light Curve of V838 MonLight Curve of V838 Mon
V838 Mon’s Light EchoV838 Mon’s Light Echo
Image combining HST/ACS images by AAVSO observer and professional astronomer Peter Garnavich
37% of the requests for variable star data in 2000/2001 were for dwarf novae, novae, and nova-like stars
EB & RR Lyr1%
Semiregular2%
Novae & Nova-like9%
Dwarf Novae28%
Mira49%
RV Tau2%
Misc.4%
R CrB2%
X-Ray3%
2000/2001 AAVSO Data Requests2000/2001 AAVSO Data Requests
2000/2001 AAVSO Data Requests2000/2001 AAVSO Data Requests
Elem. - Undergrad. Students
10%
Educators2%
Amateur Astronomers
13%
Professional Astronomers
68%
Graduate Students
6%Press1%
Professional astronomers most commonly request AAVSO data
IUE
Kitt Peak
HST
Cerro Tololo
Chandra
Amateur Astronomers Contributed Data for the Amateur Astronomers Contributed Data for the Following SatellitesFollowing Satellites
(satellites in chronological order)
Apollo-Soyuz * Extreme UV
ANS * X-ray
Ariel V * X-ray
HEAO-1/2 * X-ray
IRAS * IR
IUE * UV
Voyager * Far UV
ASTRO-1 * UV
ASTRO-2 * UV
EXOSAT * X-ray
ROSAT * X-ray
HST * Multiwavelength
Hipparcos * Astrometry
ISO * IR
GINGA * X-ray
EUVE * Extreme UV
ORFEUS * UV
BeppoSAX * X-ray
ASCA * X-ray
CGRO * Gamma ray
RXTE * X-ray
FUSE * Far UV
Chandra * X-ray
XMM-Newton * X-ray
Seeing CVs in a Different LightSeeing CVs in a Different Light
EXOSAT Light
Curve of U Gem
EXOSAT Light
Curve of AM Her
ASCA Light
Curve of AO Psc
EXOSAT Light
Curve of QQ Vul
Amateur and Professional Astronomers Team Up for Chandra Observations of SS Cygni
September 14, 2000 - Triggered by alerts from amateur astronomers worldwide NASA's Chandra X-Ray Observatory is observing the outburst of the brightest northern dwarf nova SS Cygni. The amateur stargazers provided Chandra scientists with a crucial early-warning of this outburst by calling-in their visual observations of SS Cygni as soon as they saw the star brightening. With the cooperation of hundreds of amateur astronomers, the Chandra observatory is monitoring SS Cygni's X-ray emission during its maximum brightness. Chandra X-ray Observatory
The amateur's observations of this star are done with backyard optical telescopes. The data they provide about the star's optical brightening, combined with the X-ray spectra gathered by the Chandra satellite, will reveal the nature of the flow of gas from a small red star onto its shrunken, dying companion.
Dr. Janet A. Mattei, Director of the American Association of Variable Star Observers (AAVSO)--a non-profit organization made up of mostly amateur astronomers -- and her technical staff are coordinating the collection of optical observations of SS Cygni and communicating them to Dr. Chistopher Mauche at Lawrence Livermore National Observatory, CA who is the Principal Investigator of Chandra observations.
More at: http://chandra.harvard.edu/chronicle/0300/aavso.html
Sometimes the little things in life count the most, especially when it comes to backyard stargazers making major contributions to the field of professional astronomy.
Dr. Janet A. Mattei, director of the American Association of Variable Star Observers (AAVSO), discusses some of the unique partnerships formed in the area of variable stars (stars that change in brightness) between professional and amateur astronomers at the American Astronomical Society meeting today in Rochester, N.Y.
Press Release
Calling All Amateur Stargazers: NASA Needs You
THE AMERICAN ASSOCIATION OF VARIABLE STAR OBSERVERS25 Birch Street, Cambridge, MA 02138 USA
Tel. 617-354-0484 Fax 617-354-0665http://www.aavso.org
Contact:Janet A. MatteiAAVSO(617) 354 [email protected]
PRESS RELEASE:Monday, June 5, 10:00 a.m
More at: http://www.aavso.org/meetings/press1.stm
RXTEGOF RXTE Observes Dwarf Nova Outbursts RXTEFAQ
In October 1996 the brightest dwarf nova in the sky - SS Cygni - went into outburst, and was observed for the next twelve days by RXTE (P.I. Peter Wheatley), EUVE (P.I. Chris Mauche), and the American Association of Variable Star Observers (AAVSO) (headed by Janet Mattei). The three light curves are shown in Figure 1. SS Cygni has historically been considered by the AAVSO to be their highest priority object because of its interesting behavior and brightness. It has been observed for over 100 years, and recently has often been the target of coordinated campaigns employing several satellites. SS Cyg has an orbital period of 6.6 hrs and goes into outburst about once every 50 days, during which time its optical flux increases by ~3.5 magnitudes. The durations of the outbursts in SS Cyg show a bimodal distribution: they last either ~7 days or ~14 days, and usually these alternate. (The Oct 1996 outburst was a short one.)
More at: http://heasarc.gsfc.nasa.gov/docs/xte/Greatest_Hits/wheatley.html
SS Cyg and U GemSS Cyg and U Gemin Three Wavelengthsin Three Wavelengths
The light curve in three wavelengths of an SS Cyg (right) and U Gem (left) outburst.
More at: http://heasarc.gsfc.nasa.gov/docs/xte/Greatest_Hits/wheatley.html
EUVE ObservationsEUVE Observations
Mauche, C.W., Mattei, J.A., & Bateson, F. 2001, in Evolution of Binary and Multiple Star Systems
VW Hyi: Normal OutburstVW Hyi: Normal Outburst
Mauche, C.W., Mattei, J.A., & Bateson, F. 2001, in Evolution of Binary and Multiple Star Systems
In VW Hyi, the optical-EUV delay is about 0.75 day; the optical-Voyager FUV delay (triangles) is about 0.5 day.
VW Hyi: SuperoutburstsVW Hyi: Superoutbursts
There is a dramatic decline in the EUV flux of VW Hyi just before the optical flux returns to quiescent value (left). The subsequent
rebound of the EUV flux coincides with the return of hard “thermal brems” component of the boundary layer spectrum (right).
Mauche, C.W., Mattei, J.A., & Bateson, F. 2001, in Evolution of Binary and Multiple Star Systems
OY Car: SuperoutburstsOY Car: Superoutbursts
The optical and EUV light curves of OY Car in superoutburst suggest that we are seeing in the EUV the decay of a normal outburst and the subsequent
rise of a long outburst which “add” to produce the superoutbust.
Mauche, C.W., Mattei, J.A., & Bateson, F. 2001, in Evolution of Binary and Multiple Star Systems
U Gem’s Anomalous OutburstU Gem’s Anomalous Outburst
Frequency histogram distribution of all outburst
durations in U Gem, compiled from the long-
term AAVSO light curve.The two straight lines with slopes of
26 d mag-1 and 1.4 d mag-1, respectively.Cannizzo, J.K., Gehrels, N., & Mattei, J.A. 2002, ApJ, submitted
U Gem’s Anomalous OutburstU Gem’s Anomalous Outburst
The apparent visual
magnitude
The disk mass
The rate of accretion onto
the WD
Cannizzo, J.K., Gehrels, N., & Mattei, J.A. 2002, ApJ, submitted
Amateur astronomers worldwide have helped:
• In discovering novae
• To obtain the first detection of X-ray emission from members of each CV category
• To obtain the first detection of soft X-ray pulsations from dwarf novae
• To obtain the first multi-wavelength spectra of dwarf novae
• To obtain multi-color photometry and spectroscopy at all stages of outburst of CVs
Contributions of Amateur Astronomers Contributions of Amateur Astronomers to Cataclysmic Variable Researchto Cataclysmic Variable Research
• In the discovery that mass loss occurs in the form of winds during outburst in some CVs
• In the discovery of coherent and quasi-coherent oscillations during outbursts of dwarf novae
• In the discovery that there is a delay between optical, ultraviolet, far ultraviolet, and extreme ultraviolet brightening in some novae
• In the discovery that the EUV and soft X-ray fluxes rise and the hard X-ray flux falls during the rise to optical outburst
• In the discovery that EUV soft X-ray fluxes initially track the optical flux, but falls more quickly during the decline from outburst
• In the discovery that the hard X-ray flux remains suppressed throughout the outburst, but recovers suddenly at the end of the optical outburst
• In the discovery of radio emission from some dwarf novae
• In providing a continuous record of behavior of CVs so that both multi-wavelength observations and theory can be correlated with optical data
• In furthering our understanding of compact binaries in terms of accretion disks, the nature and origin of the outbursts, the nature of the white dwarf, and the nature of the secondary
• In the discovery that 70% of CVs emit X-rays without being phase dependent (information vital in testing theories for high energy emission in compact systems)
A special thanks to observers worldwide
for their many decades of
observations. We gratefully
acknowledge the NASA grants to the AAVSO that enabled the collaboration of
amateur and professional astronomers!