Variable Stars and the AAVSO Arne Henden Director, AAVSO

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!

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

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

AAVSO HQ 2km from Harvard/CfA

Today’s Observers

Comet PanSTARRs changing tail structure total brightness nuclear brightness rotation period jet activity Comet ISON due in 2014 Credit: Lorenzo Comolli

Amateur spectroscopic setup

PanSTARRs bright comets can be observed with amateur spectrographs

Lunar photos good test target videocam impacts LCROSS

T Pyx latest

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

T Pyx latest

T Pyx latest light curve

T Pyx visual and Xray comparison

T Pyx nm outburst spectrum

T Pyx Halpha hires spectrum

M101 + SN2011fe Credit: Albert Duin

SN2011fe latest light curve

SN2012aw in M95

SN2012aw light curve

M65 supernova SN2013am Credit: Wendel & Masi

Amateur Spectroscopy t.htmhttp://astrosurf.com/buil/saintcaprais/firs t.htm Observatoire de Saint-Caprais Rabastens (Tarn) Yvon Rieugné et Pierre Thierry

Thierry’s 94cm

SN2011fe spectrum

MASTER OT J LP binary or RCB? Denisenko et al. ATEL 4784 Credit: ASAS

GR Ori 05:21: :10:10.2 WZ Sge; last outburst 1916

AZ Cas

Cookbook for VS observing Use VSX or AAVSO Campaigns, observing programs to select object; Example: V435 Cam –06:15: :08:13.4 J2000 –13.7 – 14.1 R –Period 112 minutes

Generate finding chart DSS option gives true sky view

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

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

Analyze data Spreadsheet with the correct period Use VSTAR for phase plotting and period analysis:

Submit data Get an AAVSO observer code: Use Webobs to upload your data:

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!

AAVSO news

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

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

2GSS telescope

Anderson Mesa Dark Sky Site (Flagstaff, AZ)

2GSS site

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

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

LP binary or RCB?