engleski

Search for small – amplitude long – period pulsating variables in Stripe 82

We report the results of a search for small- amplitude (A < 0.3 mag) long-period (P > 100 days) sources with periodic variability in SDSS Stripe 82 region. The SDSS coverage of Stripe 82 enables such a search because there are on average 20 observations per band in ugriz bands for about 1 million stars, collected over about 6 years, with a faint limit of r ∼ 22 mag and precisely calibrated 1-2% photometry. We calculated the periods of candidate variable objects in this sample using the LombScargle periodogram and considered the three highest periodogram peaks in each of the gri filters as relevant. Only those sources with gri periods consistent to within 0.1% were later studied. We focus our search on periodic variables with periods 100 < P < 600 days and uniform distribution of data points in phased light curves. We present 84 possible variable candidates out of which at least 11 have plausible periodic variability. This sample contains a bona- fide quasar with a periodic optical light curve. This SDSS-based search bodes well for future sensitive large-area surveys, such as the Rubin Observatory Legacy Survey of Space and Time, which should obtain several hundred times larger sample of small-amplitude long-period variable stars due to its larger sky coverage (about a factor of 60) and improved sensitivity (∼ 2 mag).

pulsating variables ; light curve

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