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Title: NO EVIDENCE FOR CLASSICAL CEPHEIDS AND A NEW DWARF GALAXY BEHIND THE GALACTIC DISK

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 K{sub s}-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 ofmore » a few days that can mimic pulsations and even eclipses.« less
Authors:
; ; ; ; ; ; ; ; ; ; ;  [1]
  1. Warsaw University Observatory, Al. Ujazdowskie 4, 00-478 Warszawa (Poland)
Publication Date:
OSTI Identifier:
22518689
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal Letters; Journal Volume: 813; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; CEPHEIDS; DISTANCE; ECLIPSE; IMAGES; MILKY WAY; NEAR INFRARED RADIATION; NITRIC OXIDE; PULSATIONS; VISIBLE RADIATION