Carbon Stars and other Luminous Stellar Populations in M33

Abstract

The M33 galaxy is a nearby, relatively metal-poor, late-type spiral. Its proximity and almost face-on inclination means that it projects over a large area on the sky, making it an ideal candidate for wide-field CCD mosaic imaging. Photometry was obtained for more than 10^6 stars covering a 74' x 56' field centered on M33. Main sequence (MS), supergiant branch (SGB), red giant branch (RGB) and asymptotic giant branch (AGB) populations are identified and classified based on broad-band V and I photometry. Narrow-band filters are used to measure spectral features allowing the AGB population to be further divided into C and M-star types. The galactic structure of M33 is examined using star counts, colour-colour and colour-magnitude selected stellar populations. We use the C to M-star ratio to investigate the metallicity gradient in the disk of M33. The C/M-star ratio is found to increase and then flatten with increasing galactocentric radius in agreement with viscous disk formation models. The C-star luminosity function is found to be similar to M31 and the SMC, suggesting that C-stars should be useful distance indicators. The ``spectacular arcs of carbon stars'' in M33 postulated recently by Block et al. (2004) are found in our work to be simply an extension of M33's disk.

20 pages, 20 figures. Accepted for publication in The Astronomical Journal

References in corpus (4)

• The Ghost of Sagittarius and Lumps in the Halo of the Milky Way
• Evidence for Stellar Substructure in the Halo and Outer Disk of M31
• One Ring to Encompass them All: A giant stellar structure that surrounds the Galaxy
• Carbon star populations in systems with different metallicities: statistics in Local Group galaxies

Cited by in corpus (26)

• The Detection of Inside-out Disk Growth in M33
• The metallicity gradient of M 33: chemical abundances of HII regions
• Star formation in M33: multiwavelength signatures across the disk
• The building up of the disk galaxy M33 and the evolution of the metallicity gradient
• Deep CFHT Photometric Survey of the Entire M33 Galaxy I: Catalogue of 36000 Variable Point Sources
• The Stellar Populations of M33's Outer Regions IV: Inflow History and Chemical Evolution
• The Stellar Populations of M33's Outer Regions III: Star Formation History
• Is there a metallicity ceiling to form carbon stars? - A novel technique reveals a scarcity of C stars in the inner M31 disk
• AGB stars as tracers of metallicity and mean age across M33
• Synthetic photometry for carbon-rich giants II. The effects of pulsation and circumstellar dust
• Carbon stars as standard candles: I. The luminosity function of carbon stars in the Magellanic Clouds
• The Stellar Populations of M33's Outer Regions II: Deep ACS Imaging
• The Red Supergiant Content of M31 and M33
• The UK Infrared Telescope M33 monitoring project. I. Variable red giant stars in the central square kiloparsec
• Properties of carbon stars in the Solar neighbourhood based on Gaia DR2 astrometry
• The UK Infrared Telescope M33 monitoring project. IV. Variable red giant stars across the galactic disc
• CXOGBS~J173620.2--293338: A Candidate Symbiotic X-ray Binary Associated with a Bulge Carbon Star
• The assessment of the near infrared identification of Carbon stars. I. The Local Group galaxies WLM, IC 10 and NGC 6822
• The Evolution and Star Formation History of M33
• Near-infrared spectroscopy of AGB star candidates in Fornax, Sculptor and NGC 6822
• Carbon Stars in the Satellites and Halo of M31
• Keck spectroscopy and Spitzer Space Telescope analysis of the outer disk of the Triangulum Spiral Galaxy M33
• Luminous AGB stars in nearby galaxies. A study using Virtual Observatory tools
• Massive young stellar objects in the Local Group spiral galaxy M33 identified using machine learning
• The Building of Galactic Disks: Insights from the Triangulum Spiral Galaxy Messier 33
• The Astrophysical Distance Scale: V. A 2% Distance to the Local Group Spiral M33 via the JAGB Method, Tip of the Red Giant Branch, and Leavitt Law