A comprehensive study of Cepheid variables in the Andromeda galaxy. Period distribution, blending and distance determination

Abstract

Extragalactic Cepheids are the basic rungs of the cosmic distance scale. They are excellent standard candles, although their luminosities and corresponding distance estimates can be affected by the particular properties of the host galaxy. Therefore, the accurate analysis of the Cepheid population in other galaxies, and notably in the Andromeda Galaxy (M31), is crucial to obtaining reliable distance determinations. We obtained accurate photometry (in B and V passbands) of 416 Cepheids in M31 over a five year campaign within a survey aimed at the detection of eclipsing binaries. The resulting Cepheid sample is the most complete in M31 and has almost the same period distribution as the David Dunlap Observatory sample in the Milky Way. The large number of epochs (~250 per filter) has permitted the characterisation of the pulsation modes of 356 Cepheids, with 281 of them pulsating in the fundamental mode and 75 in the first overtone. The period-luminosity relationship of the fundamental mode Cepheids has been studied and a new approach has been used to estimate the effect of blending. We find that the blending contribution is as important as the metallicity correction when computing Cepheid distance determinations to M31 (~0.1 mag). Since large amplitude Cepheids are less affected by blending, we have used those with an amplitude A_V>0.8 mag to derive a distance to M31 of (m-M)_0=24.32+/-0.12 mag.

10 pages, 9 figures; accepted for publication in A&A

References in corpus (3)

• A new Cepheid distance to the maser-host galaxy NGC 4258 and its implications for the Hubble Constant
• Cepheid Parallaxes and the Hubble Constant
• Eclipsing binaries suitable for distance determination in the Andromeda galaxy

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• On the distance and reddening of the starburst galaxy IC10
• Properties of M31. II: A Cepheid disk sample derived from the first year of PS1 PAndromeda data
• Temperature Differences in the Cepheid Instability Strip Require Differences in the Period-Luminosity Relation in Slope and Zero Point
• The M31 Near-Infrared Period-Luminosity Relation and its non-linearity for $\delta$ Cep Variables with $0.5\le \log (P)\le 1.7$
• VI-Band Follow-Up Observations of Ultra-Long-Period Cepheid Candidates in M31