OGLE-III Mus101.2 60905 , the SIMBAD biblio

2015ApJ...813L..40P - Astrophys. J., 813, L40 (2015/November-2)

No evidence for classical cepheids and a new dwarf galaxy behind the galactic disk.

PIETRUKOWICZ P., UDALSKI A., SZYMANSKI M.K., SOSZYNSKI I., PIETRZYNSKI G., WYRZYKOWSKI L., POLESKI R., ULACZYK K., SKOWRON J., MROZ P., PAWLAK M. and KOZLOWSKI S.

Abstract (from CDS):

Based on data from the ongoing OGLE Galaxy Variability Survey (OGLE GVS), we have verified observed properties of stars detected by the near-infrared VVV survey in a direction near the Galactic plane at longitude l ≈ -27° and recently tentatively classified as classical Cepheids belonging to, hence claimed, a dwarf galaxy at a distance of about 90 kpc from the Galactic Center. Three of four stars are detected in the OGLE GVS I-band images. We show that two of the objects are not variable at all, and the third one with a period of 5.695 days and a nearly sinusoidal light curve of an amplitude of 0.5 mag cannot be a classical Cepheid and is very likely a spotted object. These results together with a very unusual shape of the Ks-band light curve of the fourth star indicate that it is very likely that none of them is a Cepheid and, thus there is no evidence for a background dwarf galaxy. Our observations show that great care must be taken when classifying objects by their low-amplitude close-to-sinusoidal near-infrared light curves, especially with a small number of measurements. We also provide a sample of high-amplitude spotted stars with periods of a few days that can mimic pulsations and even eclipses.

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Journal keyword(s): galaxies: dwarf - Galaxy: disk - stars: variables: Cepheids

Simbad objects: 12

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