The extended disc and halo of the Andromeda galaxy observed with<i>Spitzer</i>-IRAC

Ravandi, M. Rafiei; Barmby, P.; Laine, Seppo; Davidge, T. J.; Zhang, Jenna; Bianchi, Luciana; Babul, Arif; Chapman, Scott

doi:10.1093/mnras/stw652

Cited by 3 publications

(1 citation statement)

References 46 publications

(45 reference statements)

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“…We implement strict point-source detection criteria by adopting a sharp and round cut-off for all sources detected at 3.6 and 4.5 μm (only sources with sharpness and roundness values within 1.75σ of the respective mean values were kept); this effectively removes Figure 1. Location of our Spitzer IRAC pointings towards M32 (blue solid lines) superimposed on an IRAC 3.6 μm mosaic of M31 (Barmby et al 2006;Rafiei Ravandi et al 2016). We limit our variability search to the region centred on M32, where these pointings and the IRAC 3.6 and 4.5 μm data overlap.…”

Section: O B S E Rvat I O N S a N D P H Oto M E T Rymentioning

confidence: 99%

Infrared variable stars in the compact elliptical galaxy M32

Jones

Nally

Sharp

et al. 2021

Monthly Notices of the Royal Astronomical Society

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Variable stars in the compact elliptical galaxy M32 are identified, using three epochs of photometry from the Spitzer Space Telescope at 3.6 and 4.5 μm, separated by 32 to 381 days. We present a high-fidelity catalogue of sources detected in multiple epochs at both 3.6 and 4.5 μm, which we analysed for stellar variability using a joint probability error-weighted flux difference. Of these, 83 stars are identified as candidate large-amplitude, long-period variables, with 28 considered high-confidence variables. The majority of the variable stars are classified as asymptotic giant branch star candidates using colour-magnitude diagrams. We find no evidence supporting a younger, infrared-bright stellar population in our M32 field.

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Section: O B S E Rvat I O N S a N D P H Oto M E T Rymentioning

confidence: 99%

Infrared variable stars in the compact elliptical galaxy M32

Jones

Nally

Sharp

et al. 2021

Monthly Notices of the Royal Astronomical Society

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Stellar populations in the outskirts of M31: the mid-infrared view

Barmby

Ravandi

2016

Proc. IAU

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The mid-infrared provides a unique view of galaxy stellar populations, sensitive to both the integrated light of old, low-mass stars and to individual dusty mass-losing stars. We present results from an extended Spitzer/IRAC survey of M31 with total lengths of 6.6 and 4.4 degrees along the major and minor axes, respectively. The integrated surface brightness profile proves to be surprisingly diffcult to trace in the outskirts of the galaxy, but we can also investigate the disk/halo transition via a star count profile, with careful correction for foreground and background contamination. Our point-source catalog allows us to report on mid-infrared properties of individual objects in the outskirts of M31, via cross-correlation with PAndAS, WISE, and other catalogs.Comment: Proceedings of IAU Symposium 321, "Formation and evolution of galaxy outskirts", Eds. A. Gil de Paz, J. C. Lee & J. H. Knapen, Cambridge University Press, Cambridg

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Photometric and Spectroscopic Analysis of LBV Candidate J004341.84+411112.0 in M31

Sarkisyan¹,

Sholukhova²,

Fabrika³

et al. 2022

Res. Astron. Astrophys.

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We study Luminous Blue Variable (LBV) candidate J004341.84+411112.0 in the Andromeda galaxy. We present optical spectra of the object obtained with the 6-m telescope of SAO RAS. The candidate shows typical LBV features in its spectra: broad and strong hydrogen lines and the HeI lines with P Cigni profiles. Its remarkable spectral resemblance to the well known LBV P Cygni suggests a common nature of the objects and supports LBV classification of J004341.84+411112.0. We estimate the temperature, reddening, radius and luminosity of the star using its spectral energy distribution. Obtained bolometric luminosity of the candidate (M bol = -10.40±0.12 mag) is quite similar to those of known LBV stars in the Andromeda galaxy. We analysed ten year light curve of the object in R filter. The candidate demonstrates photometric variations of the order of 0.4 mag, with an overall brightness increasing trend ΔR > 0.1 mag. Therewith, the corresponding colour variations of the object are fully consistent with LBV behavior when a star become cooler and brighter in the optical spectral range with a nearly constant bolometric luminosity. LBV-type variability of the object, similarity of its spectrum and estimated luminosity to those of known LBVs allows us to classify J004341.84+411112.0 as a LBV.

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The extended disc and halo of the Andromeda galaxy observed withSpitzer-IRAC

Cited by 3 publications

References 46 publications

Infrared variable stars in the compact elliptical galaxy M32

Infrared variable stars in the compact elliptical galaxy M32

Stellar populations in the outskirts of M31: the mid-infrared view

Photometric and Spectroscopic Analysis of LBV Candidate J004341.84+411112.0 in M31

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