A Search for Rare Variable Stars in Photometric Databases

A Search for Rare Variable Stars in Photometric Databases

J. Scott Shaw, University of GeorgiaNicole Kelley, UC Berkeley

The Problem

• Many interesting stages of stellar evolution occur for only a short period of time

• Therefore, stars or systems in these stages are rare

• Examples:Supernovae, NovaeAny system in Post Main Sequence evolution

The Solution

• Use surveys with VERY LARGE numbers of stars

(NSVS=20M)

• Set criteria which distinguish the target from the general population

Light curve shape JHK color from 2MASS

Systems

•M type Eclipsing Binaries

•Cool Algols

•Subdwarf B Binaries (sdB)

An M-type Eclipsing Binary Candidate in the NSVS

Cool Algols

•One star giant or subgiant, other filling Roche lobe

•Both stars G or K

•Period over 2 days

NSVS06983718 in V

ELC Model of NSVS06983718

Subdwarf B Systems

•One sdB star •sdB reveals itself when paired with a faint red star

•Narrow eclipses but blue color

NSVS04963674 in V

Results

•40+ new M dwarf systems [9]

•10 New Cool Algols [5] + 52 GS systems

•8 New sdB systems [2-3]

Conclusion

If you have enough stars and adequate search restrictions you can find rare systems

.

This work has been funded by a partnership between the National Science Foundation (NSF AST-0552798) Research Experiences for Undergraduates (REU) and the Department of Defense (DoD) ASSURE (Awards to Stimulate and Support Undergraduate Research Experiences) programs. This publication makes use of data products from the Two Micron All Sky Survey, which is a joint project of the University of Massachusetts and the Infrared Processing and Aeronautics and Space Administration and the National Science Foundation. We also thank Northern Sky Variability Survey (NSVS) and the University of California, operator of the Los Alamos National Laboratory under Contract No. W-7405-ENG-36 with the US Department of Energy.

We would also like to thank J. Orosz (SDSU)for the use of his ELC code

AcknowledgementsAcknowledgements