A Spitzer Space Telescope survey of extreme Asymptotic Giant Branch stars in M32

Abstract

We investigate the population of cool, evolved stars in the Local Group dwarf elliptical galaxy M32, using Infrared Array Camera observations from the Spitzer Space Telescope. We construct deep mid-infrared colour-magnitude diagrams for the resolved stellar populations within 3.5 arcmin of M32's centre, and identify those stars that exhibit infrared excess. Our data is dominated by a population of luminous, dust-producing stars on the asymptotic giant branch (AGB) and extend to approximately 3 mag below the AGB tip. We detect for the first time a sizeable population of `extreme' AGB stars, highly enshrouded by circumstellar dust and likely completely obscured at optical wavelengths. The total dust-injection rate from the extreme AGB candidates is measured to be $7.5\times 10^{-7}$ ${\mathrm{M}}_{\odot }{\mathrm{yr}}^{-1}$, corresponding to a gas mass-loss rate of $1.5\times 10^{-4}$ ${\mathrm{M}}_{\odot }{\mathrm{yr}}^{-1}$. These extreme stars may be indicative of an extended star-formation epoch between 0.2 and 5 Gyr ago.

arXiv commentAccepted for publication in MNRAS, 14 pages, 12 figures, 3 tables

References in corpus (53)

• The Infrared Array Camera (IRAC) for the Spitzer Space Telescope
• The Spitzer Space Telescope Mission
• Structure and Formation of Elliptical and Spheroidal Galaxies
• Spitzer Survey of the Large Magellanic Cloud, Surveying the Agents of a Galaxy's Evolution (SAGE) I: Overview and Initial Results
• Star counts in the Galaxy. Simulating from very deep to very shallow photometric surveys with the TRILEGAL code
• Absolute Calibration of the Infrared Array Camera on the Spitzer Space Telescope
• Evolution of asymptotic giant branch stars I. Updated synthetic TP-AGB models and their basic calibration
• Reduction Algorithms for the Multiband Imaging Photometer for Spitzer
• Absolute Calibration and Characterization of the Multiband Imaging Photometer for Spitzer. I. The Stellar Calibrator Sample and the 24 micron Calibration
• Stellar Models and Yields of Asymptotic Giant Branch Stars
• Point Source Extraction with MOPEX
• Number Counts At 3 < lambda < 10 um From the Spitzer Space Telescope
• The global gas and dust budget of the Large Magellanic Cloud: AGB stars and supernovae, and the impact on the ISM evolution
• Spitzer SAGE survey of the Large Magellanic Cloud II: Evolved Stars and Infrared Color Magnitude Diagrams
• Spitzer/MIPS Infrared Imaging of M31: Further Evidence for a Spiral/Ring Composite Structure
• Surveying the Agents of Galaxy Evolution in the Tidally-Stripped, Low Metallicity Small Magellanic Cloud (SAGE-SMC) II. Cool Evolved Stars
• Tidal Interaction of M32 and NGC 205 with M31: Surface Photometry and Numerical Simulations
• The Dust Budget of the SMC: Are AGB Stars the Primary Dust Source at Low Metallicity?
• Dusty waves on a starry sea: the mid-infrared view of M31
• The Mass-Loss Return From Evolved Stars to The Large Magellanic Cloud VI: Luminosities and Mass-Loss Rates on Population Scales
• The metallicity gradient as a tracer of history and structure: the Magellanic Clouds and M33 galaxies
• An almost head-on collision as the origin of two off-centre rings in the Andromeda galaxy
• MIPS 24-160 micron photometry for the Herschel-SPIRE Local Galaxies Guaranteed Time Programs
• A new formation model for M32: A threshed early-type spiral?
• Hubble Space Telescope Observations of M32: The Color-Magnitude Diagram
• The Magellanic zoo: Mid-infrared Spitzer spectroscopy of evolved stars and circumstellar dust in the Magellanic Clouds
• Does M31 result from an ancient major merger?
• A Population of Compact Elliptical Galaxies Detected with the Virtual Observatory
• AGB stars in the Magellanic Clouds. I. The C/M ratio
• The First Empirical Mass Loss Law for Population II Giants
• Constraining stellar population models - I. Age, metallicity, and abundance pattern compilation for Galactic globular clusters
• The M33 Variable Star Population Revealed by Spitzer
• The UK Infrared Telescope M33 monitoring project. III. Feedback from dusty stellar winds in the central square kiloparsec
• Carbon star populations in systems with different metallicities: statistics in Local Group galaxies
• Is there a metallicity ceiling to form carbon stars? - A novel technique reveals a scarcity of C stars in the inner M31 disk
• Radial Age and Metal Abundance Gradients in the Stellar Content of M32
• Carbon-rich dust production in metal-poor galaxies in the Local Group
• A Spitzer Study of Asymptotic Giant Branch Stars. III. Dust Production and Gas Return in Local Group Dwarf Irregular Galaxies
• An analysis of the composite stellar population in M32
• Is Dust Forming on the Red Giant Branch in 47 Tuc?
• The Star Formation History of M32
• The VMC survey III. Mass-loss rates and luminosities of LMC AGB stars
• A Spitzer/IRAC Census of the Asymptotic Giant Branch Populations in Local Group Dwarfs. I. WLM
• RR Lyrae variables in M32 and the disk of M31
• The Deepest HST Color-Magnitude Diagram of M32: Evidence for Intermediate-Age Populations
• The ancient stellar population of M32: RR Lyr Variable stars confirmed
• An Ancient Metal-Poor Population in M32, and Halo Satellite Accretion in M31, Identified by RR Lyrae Stars
• A point source survey of M31 with the Spitzer Space Telescope
• A Spitzer IRAC Census of the Asymptotic Giant Branch Populations in Local Group Dwarfs. II. IC 1613
• Carbon enrichment of the evolved stars in the Sagittarius dwarf spheroidal
• Seeing Red in M32: Constraints on the Stellar Content from Near- and Mid-Infrared Observations and Applications for Studies of More Distant Galaxies
• The chemistry of extragalactic carbon stars
• The Mid-IR Contribution Of Dust Enshrouded Stars In Six Nearby Galaxies

Cited by in corpus (7)

• An Infrared Census of DUST in Nearby Galaxies with Spitzer (DUSTiNGS), II. Discovery of Metal-poor Dusty AGB Stars
• AGB and SAGB stars: modelling dust production at solar metallicity
• Probing the dusty stellar populations of the Local Volume Galaxies with JWST/MIRI
• ALMA reveals sunburn: CO dissociation around AGB stars in the globular cluster 47 Tucanae
• Extended Dust Emission from Nearby Evolved Stars
• Carbon Stars in the Satellites and Halo of M31
• Infrared variable stars in the compact elliptical galaxy M32