Title: The Excitement of Variable Star Observing
1The Excitement of Variable Star Observing
- Arne Henden
- Director, AAVSO
- arne_at_aavso.org
2American Association of Variable Star Observers
- Founded in 1911
- 3000 total observers in 60 countries
- 900,000 observations received yearly
- 13 million total, on-line, observations
- We provide tutorials, mentoring, workshops,
connection with professionals, campaigns, etc. - Website http//www.aavso.org
3AAVSO Headquarters are in Cambridge, MA
USA (about 2km from Harvard College Observatory)
4Typical Visual Observer Albert Jones, NZ 32cm
reflector he built in 1948 He has 500,000
lifetime observations
5Non-typical Observer E.O. Smiths private
Calypso Observatory, a 1.2m scope at Kitt Peak.
He does high-resolution Stellar imaging
6You dont always need fancy personal
equipment Esteve Duran Observatory, a public
observatory In Spain. 60cm telescope and CCD,
studying variable stars
7Not all professional telescopes are huge the
Stare telescope on Tenerife a 12cm aperture with
CCD for exoplanet studies
8The XO Project 2x10cm telephoto Lenses with
CCD At Maui, Hawaii. Exoplanet studies
9The line between amateurs and professionals is
blurring due to high-quality commercial telescopes
10and because of high-quality, inexpensive
commercial cameras
11Variable Stars
- Stars that change in brightness
- Sometimes cyclical sometimes chaotic, sometimes
just an outburst (or even an explosion,
destroying the star!) - About two percent of all stars show some change
in brightness, including our Sun
12RR Lyr variables in M3 Stanek/CfA
13How Amateurs are contributing to Variable-Star
Studies
- Obtaining light curves and analyzing eclipsing
binaries - Observing cataclysmic variables
- Long-term monitoring of Mira variables
- Finding unusual objects - gamma-ray bursts,
microlensing stars, exoplanets
14Eclipsing Binaries
- - Thousands known
- Light curves give us information about stars
(mass, size, temperature) - usually short period, easy to follow
15Observations of HD126080 with 6cm telescope and
CCD Gomez-Forrellad Garcia-Melendo 1997
3 year period eclipse was a month long Terrell
et al. 2003
16Cataclysmic Binaries
- Hundreds known
- Usually faint, go into several-magnitude outburst
on infrequent basis (weeks/years) - Interacting binaries - one star is accreting
matter from the other - Excellent targets for long-term monitoring and
short-term campaigns
17SS Cyg, a typical cataclysmic variable light
curve from 1896 to 2004
18Helping astronomers trigger satellite observations
19Pulsating Variables
- Usually periodic, from hours (RR Lyr) to years
(Miras) - Amplitude of pulsation from millimag (delta
Scuti) to many magnitudes (Miras) - Great long-term monitoring projects to watch for
evolutionary evidence
20Mira Variables
R And, P 409.33 d
Long-period variables can be some of the
prettiest stars to observe
Typical AAVSO finding chart
21You can observe single pulsation cycles
V Hya
or follow decades-long trends
22Obtaining light curves of microlensing candidates
Credit J. Skowron
Planet Mass 13 ME
Note amateurs discovered closest microlensed
star (Casseopeia) November 2006 8th magnitude at
peak
Credit NASA
23Gamma-ray bursts occur when a massive star
explodes. Detected with satellites, which then
alert ground-based telescopes
Two views of a GRB explosion, from NASA
24Light curve for a bright GRB afterglow, observed
by amateurs
25Transit of mercury - like an exoplanet transit,
it blocks part of the light from our Sun during
its passage across the disk of the Sun
26Two exoplanet transits (much bigger than Jupiter)
27For More Information
- http//www.aavso.org (we have Spanish
translations of our Visual Observing Manual,
brochure, press releases) - http//cba.phys.columbia.edu for CVs
- http//www.socastrosci.org for CCDs