On the variable nature of galactic and extra-galactic objects with sources from the Faint Sky Variability Survey

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The Faint Sky Variability Survey (FSVS) has cataloged ˜23 square degrees in BVI filters from ˜16 25 mag to investigate variability in faint sources at moderate to high Galactic latitudes. Multi-epoch (10 30) observations were made in V spanning minutes to years with amplitude sensitivities of ˜0.015 0.075 mag for V = 18 22 mag. The fraction of point sources found to be variable is 5 8% over V = 17.5 22.0 mag. Overall, the dominant population of variable sources are bluer than B-V = 0.65 and have Main Sequence colors, likely reflecting larger populations of RR Lyrae, SX Phe, γ Doradus, and W UMa variables. The population of ultracool dwarfs has been investigated using a V-I color selection. An L2 dwarf is the coolest source thus far spectroscopically identified with candidates predicted as cool as L8. Variability information for ultracool dwarfs is limited as the cooler sources become exceedingly faint in V, and thus, variability information only reaches to mid-late M type dwarfs. Follow-up photometry in the I has revealed variability in an M8 9 and L2 dwarf, with the M8 9 dwarf showing a 3 hour periodicity likely attributable to rotational modulation of surface features. The population of cataclysmic variables (CVs) has been investigated using a B-V, V-I color and variability selection to search for a “missing” population of evolved, low mass transfer types. Two known CVs were observed in the FSVS, GO Com and V394 Lyr, with two periods proposed for V394 Lyr of 2.2 and 5.7 hours. From the sample of CV candidates, a few were identified with follow-up observations to be likely pulsational variables (e.g., RR Lyrae), a W UMa binary, a M dwarf flare star, and a quasar. A sample of known and newly discovered quasars have been investigated for variability. Few quasars (˜10%) are found with intranight and day time-scale variability where as the entire sample shows long month-year time- scale variability at greater amplitudes. A sample of low redshift, low luminosity quasars classified as point sources are found to have correlated variability with changes in the seeing FWHM to ˜0.03 mag/arcsec, bringing into question the variability found in other quasar variability studies.

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