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Cataclysmic Variables in the AAVSO Observing Program Janet A. Mattei Kerriann H. Malatesta AAVSO Second HEA Workshop July 4-5, 2002, Waikoloa Beach, Hawaii.

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Presentation on theme: "Cataclysmic Variables in the AAVSO Observing Program Janet A. Mattei Kerriann H. Malatesta AAVSO Second HEA Workshop July 4-5, 2002, Waikoloa Beach, Hawaii."— Presentation transcript:

1 Cataclysmic Variables in the AAVSO Observing Program Janet A. Mattei Kerriann H. Malatesta AAVSO Second HEA Workshop July 4-5, 2002, Waikoloa Beach, Hawaii

2 Cataclysmic 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 disk Artwork by K. Smale

3 The Many Faces of Cataclysmic Variables

4 Cataclysmic Variables in the AAVSO Observing Program

5 Dwarf 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

6 SS Cygni Stars Vary by 2-6 magnitudes, lasting 1-2 weeks Outbursts on a timescale of 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

7 SS Cygni Long-Term Light Curve and a closer look at SS Cyg Wide Outburst Narrow Outburst

8 SU Ursae Majoris Stars Narrow outbursts of about 1-2 days Brighter superoutbursts of an additional 2 magnitudes lasting about days Superhumps seen during superoutbursts Subtype:WZ Sagittae Artwork by M. Garlick

9 SU UMa and Superoutbursts Superoutbursts

10 SU UMa Subtype: WZ Sge WZ Sge is an SU UMa star with an extremely long supercycle

11 An Example of Superhumps Superhump activity of the 2001 outburst, as recorded by AAVSO observer Lew Cook (COO)

12 Past Outbursts of WZ Sge

13 Z 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

14 Z Camelopardalis Long-Term Light Curve Standstill

15 Z Cam and Standstills Standstill

16 Novae 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

17 Nova Light Curves

18 GK Persei Long-Term Light Curve Nova Outburst Dwarf Nova- Type Outbursts

19 Recurrent Novae Photometric and spectroscopically similar to novae Rapid rise to maximum Brighten by 4-9 magnitudes Decline faster than that of novae Recur every years HST image of the recurrent nova T Pyxidis

20 RS Ophiuchi Long-Term Light Curve Recurrent Nova Outburst

21 Nova-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

22 Polars (AM Her stars) White dwarf star has magnetic field of mega Gauss Accretion columns, instead of an accretion disk Synchronous rotation (P spin = P orb ) Source of hard X-ray, extreme UV, UV, as well as optical wavelengths Artwork by R. Kightley

23 Anatomy of a Polar Image from HEASARC

24 Light Curve of AM Herculis

25 Intermediate Polars (DQ Her 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

26 AAVSO Variable Star Charts Old favorites New additions

27 Cataclysmic Variables in the AAVSO Observing Program

28 When Good Stars Misbehave SU UMa takes a superoutburst hiatus U Gem has a double-wide outburst SS Aur lacks amplitude

29 Alert Notice 292 THE AMERICAN ASSOCIATION OF VARIABLE STAR OBSERVERS 25 Birch Street, Cambridge, MA USA INTERNET: Tel Fax AAVSO ALERT NOTICE 292 (January 10, 2002) 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 Confirming observations reported via the AAVSO were: Jan 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:

30 Light Curve of V838 Mon

31 V838 Mons Light Echo Image combining HST/ACS images by AAVSO observer and professional astronomer Peter Garnavich

32 37% of the requests for variable star data in 2000/2001 were for dwarf novae, novae, and nova-like stars 2000/2001 AAVSO Data Requests

33 Professional astronomers most commonly request AAVSO data

34 IUE Kitt Peak HST Cerro Tololo Chandra

35 Amateur Astronomers Contributed Data for the Following Satellites Amateur Astronomers Contributed Data for the Following 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

36 Seeing 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

37 Amateur and Professional Astronomers Team Up for Chandra Observations of SS Cygni September 14, 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:

38 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 OBSERVERS 25 Birch Street, Cambridge, MA USA Tel Fax Contact: Janet A. Mattei AAVSO (617) PRESS RELEASE: Monday, June 5, 10:00 a.m More at:

39 RXTE GOF RXTE Observes Dwarf Nova Outbursts RXTE FAQ 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:

40 SS Cyg and U Gem in Three Wavelengths The light curve in three wavelengths of an SS Cyg (right) and U Gem (left) outburst. More at:

41 EUVE Observations Mauche, C.W., Mattei, J.A., & Bateson, F. 2001, in Evolution of Binary and Multiple Star Systems

42 VW 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.

43 VW 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

44 OY 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

45 U Gems 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

46 U Gems 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

47 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 to Cataclysmic Variable Research

48 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

49 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

50 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)

51 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!


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