A Long-term photometric variability and spectroscopic study of luminous blue variable AF And in M31

Abstract

We present photometric and spectroscopic analysis of the Hubble Sandage variable AF And in M31. The data has been taken under the Nainital Microlensing Survey during 1998-2002 and follow-up observations were carried out until 2011. During this period, photometric observations in Cousins R and I bands were obtained for 169 nights spanning over about 5000 days. AF And has shown a prominent outburst around mid-January in 1999 followed by a gradual decrease in brightness of about 1.5 mag in the next 3 years with a declining rate of ~0.0015 mag/day leading to a quiescent phase at the end of 2001. After lying low for about 9 years, AF And again went through a secondary outburst phase in late 2010 with an amplitude of 0.44 mag where it lasted for one year before fading back to its quiescence phase. The spectroscopic observations of AF And show prominent Balmer and He I emission lines along with the comparatively weaker FeII and [FeII] emissions. Asymmetric emission line profiles in its spectrum imply the mass loss rate of about 2.2x10^{-4} solar mass per yr through the stellar winds in the photosphere. Using SED fitting, we find the photospheric temperature of 33,000+/-3000 K during the visual minimum. Using a weak P Cygni profile of HeI emission line, the wind terminal velocity for AF And is found to be around 280-300 km/s.

arXiv comment15 pages, 6 figures, 5 tables, accepted for the publication in The Astronomical Journal

References in corpus (42)

• Maps of Dust IR Emission for Use in Estimation of Reddening and CMBR Foregrounds
• The Sloan Digital Sky Survey: Technical Summary
• Gaia Data Release 2. Summary of the contents and survey properties
• Measuring Reddening with SDSS Stellar Spectra and Recalibrating SFD
• The Gaia mission
• Final Results from the Hubble Space Telescope Key Project to Measure the Hubble Constant
• Correcting for the Effects of Interstellar Extinction
• [O III]/[N II] as an Abundance Indicator at High Redshift
• Grids of stellar models with rotation - I. Models from 0.8 to 120 Msun at solar metallicity (Z = 0.014)
• Using Strong Lines to Estimate Abundances in Extragalactic HII Regions and Starburst Galaxies
• VOSA: Virtual Observatory SED Analyzer. An application to the Collinder 69 open cluster
• A Survey of Local Group Galaxies Currently Forming Stars. I. UBVRI Photometry of Stars in M31 and M33
• On the role of continuum-driven eruptions in the evolution of very massive stars and Population III stars
• Luminous Blue Variable eruptions and related transients: Diversity of progenitors and outburst properties
• Shell-shocked diffusion model for the light curve of SN2006gy
• Luminous Blue Variables are Antisocial: Their Isolation Implies that they are Kicked Mass Gainers in Binary Evolution
• Luminous Blue Variables as the progenitors of supernovae with quasi-periodic radio modulations
• The VLT-FLAMES survey of massive stars: Wind properties and evolution of hot massive stars in the LMC
• On the nature of the prototype LBV AG Carinae I. Fundamental parameters during visual minimum phases and changes in the bolometric luminosity during the S-Dor cycle
• The metallicity profile of M31 from spectroscopy of hundreds of HII regions and PNe
• An empirical template library of stellar spectra for a wide range of spectral classes, luminosity classes, and metallicities using SDSS BOSS spectra
• Giant Outbursts of Luminous Blue Variables and the Formation of the Homunculus Nebula Around eta Carinae
• On the Social Traits of Luminous Blue Variables
• Classical novae from the POINT-AGAPE microlensing survey of M31 -- I. The nova catalogue
• Luminous and Variable Stars in M31 and M33. II. Luminous Blue Variables, Candidate LBVs, Fe II Emission Line Stars, and Other Supergiants
• On the nature of candidate luminous blue variables in M33
• Luminous and Variable Stars in M31 and M33. IV. Luminous Blue Variables, Candidate LBVs, and the B[e] Supergiants; How to Tell Them Apart
• PAndromeda - first results from the high-cadence monitoring of M31 with Pan-STARRS 1
• Emission Line Abundances of Absorption Selected Galaxies at z<0.5
• Discovery of the first B[e] supergiants in M 31
• Identification of 13 Cepheids and 333 Other Variables in M31
• New Luminous Blue Variables in the Andromeda galaxy
• The Wendelstein Calar Alto Pixellensing Project (WeCAPP): The M31 Variable Star Catalogue
• Variable stars towards the bulge of M31: the AGAPE catalogue
• First microlensing candidate towards M31 from the Nainital Microlensing Survey
• New Luminous Blue Variable Candidates in NGC 4736
• The Wind of Variable C in M33
• Properties of M31. IV: Candidate Luminous Blue Variables from PAndromeda
• Photometric study of two novae in M31
• Nainital Microlensing Survey -- detection of short period Cepheids in the disk of M31
• Multi-Epoch BVRI Photometry of Luminous Stars in M31 and M33
• Long-term photometric study of a faint W UMa binary in the direction of M31

Cited by in corpus (4)

• A new and unusual LBV-like outburst from a Wolf-Rayet star in the outskirts of M33
• Stellar Spectral Interpolation using Machine Learning
• The Karl G. Jansky Very Large Array Local Group L-band Survey (LGLBS)
• ZTF IC 10 variable catalog