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Variable Stars and the AAVSO

Variable Stars and the AAVSO. Arne Henden Director, AAVSO arne@aavso.org. Variable Stars. Every star varies during its lifetime Physical variation (pulsation, spots) tell us about stellar structure, cosmology Geometrical variation (binaries) give us masses, densities, sizes

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Variable Stars and the AAVSO

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  1. Variable Stars and the AAVSO Arne Henden Director, AAVSO arne@aavso.org

  2. Variable Stars • Every star varies during its lifetime • Physical variation (pulsation, spots) tell us about stellar structure, cosmology • Geometrical variation (binaries) give us masses, densities, sizes • Accretion disk phenomena prevalent at all scales • Transient events (novae, supernovae, gamma-ray bursts) detail stellar evolution • If you are an astronomer, you will study variable stars sometime during your career • This is where the AAVSO enters the picture!

  3. The American Association of Variable Star Observers (AAVSO) • Dedicated to the study of variable stars • One of the largest & oldest Citizen Science organizations in the world • International: 1000 members in 45 countries • 15% professional, 85% amateur members • 3000 total observers (800 active per year) • 23 million online observations • http://www.aavso.org

  4. Cumulative observations in AAVSO International Database(current rate: 1.5M/year)

  5. AAVSO HQ 2km from Harvard/CfA

  6. Today’s Observers

  7. Comet PanSTARRschanging tail structuretotal brightnessnuclear brightnessrotation periodjet activity Comet ISON due in 2014 Credit: Lorenzo Comolli

  8. Amateur spectroscopic setup

  9. PanSTARRsbright comets can be observed with amateur spectrographs

  10. Lunar photosgood test targetvideocam impactsLCROSS

  11. T Pyx latest

  12. Artist’s conception of the T Pyx system (orbit size of moon’s orbit)

  13. T Pyx latest

  14. T Pyx latest light curve

  15. T Pyx visual and Xray comparison

  16. T Pyx 400-900nm outburst spectrum

  17. T Pyx Halpha hires spectrum

  18. M101 + SN2011fe Credit: Albert Duin

  19. SN2011fe latest light curve

  20. SN2012aw in M95

  21. SN2012aw light curve

  22. M65 supernova SN2013am Credit: Wendel & Masi

  23. Amateur Spectroscopy • http://astrosurf.com/buil/saintcaprais/first.htm • Observatoire de Saint-Caprais Rabastens (Tarn) • Yvon Rieugné et Pierre Thierry

  24. Thierry’s 94cm

  25. SN2011fe spectrum

  26. MASTER OT J095310.04+335352.8 LP binary or RCB? Denisenko et al. ATEL 4784 Credit: ASAS

  27. GR Ori05:21:34.98 +01:10:10.2WZ Sge; last outburst 1916

  28. AZ Cas

  29. Cookbook for VS observing • Use VSX or AAVSO Campaigns, observing programs to select object; http://www.aavso.org/vsx • Example: V435 Cam • 06:15:20.90 +82:08:13.4 J2000 • 13.7 – 14.1 R • Period 112 minutes

  30. Generate finding chart • http://www.aavso.org/vsp • DSS option gives true sky view

  31. Acquire data • 111min period; use 50pts/period or one every 2 minutes • Best if use both B&V, but use at least one filter • Cover entire cycle ++ if possible

  32. Process data • Dark subtract and flat field • Extract photometry using sequence to get standardized magnitudes • Output in AAVSO Extended format if possible

  33. Analyze data • Spreadsheet with the correct period • Use VSTAR for phase plotting and period analysis: • http://www.aavso.org/vstar

  34. Submit data • Get an AAVSO observer code: http://www.aavso.org/request-obscode • Use Webobs to upload your data: • http://www.aavso.org/webobs

  35. Variable stars are for you! • Easy to observe • Good subjects for research • Collaborate with professionals • Can use naked eye, binoculars, DSLR, telescope+CCD, spectrograph, etc. • Manuals/tutorials on AAVSO web site • You too can do cutting-edge science!

  36. AAVSO news

  37. 2GSS features • Immediate public access • Simultaneous color information • Prototype fully funded • Fwhm smaller than existing surveys • Entire sky covered, including galactic plane (50 million stars per night) • Long life-time (AAVSO) • Pathfinder for LSST

  38. 2GSS specs • Prototype to be installed at Lowell Observatory in June 2013 • Use of APASS for field secondary standards • Phase I has photometry available within 24hrs, public, on-line • Phase II incorporates real-time alerts

  39. 2GSS telescope

  40. Anderson Mesa Dark Sky Site (Flagstaff, AZ)

  41. 2GSS site

  42. Impact on CCD Observers • Real-time alerts need to be followed up • Photometry degrades below ~15th; provide higher-quality photometry • One-day cadence poor for short-period variables, transient objects • Only V,I’ photometry, so other wavelengths needed

  43. Impact on Visual Observers • Real-time alerts need to be followed up • One-day cadence poor for short-period variables, transient objects; little change for CV observers • Saturates at V=10-11; no coverage of brighter objects • Will have problems with moon; won’t go near horizons; blended objects difficult • Starting in 2012, but not fully operational until 2013, and then only if fully funded

  44. LP binary or RCB?

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