The distance of M 33 and the stellar population in its outskirts

Galleti, S.; Bellazzini, M.; Ferraro, F. R.

doi:10.1051/0004-6361:20040489

Cited by 98 publications

(110 citation statements)

References 61 publications

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“…The nearly face-on inclination (i = 56 degrees, Regan & Vogel 1994) of M 33 reduces extinction effects for the majority of its cluster population, situated in the disk. Also, M 33 is the only close late-type spiral galaxy, situated at a distance of 867 kpc (Galleti et al 2004, distance modulus of (m − M) 0 = 24.69), making its star cluster system accessible to ground-based telescopes for integrated photometric and spectroscopic studies and to the Hubble Space Telescope (HST) for resolved measurements. While other star cluster systems of Local Group galaxies have received considerable attention, as in the case of M 31 and the Magellanic Clouds, the M 33 star cluster system has not been studied as much.…”

Section: Introductionmentioning

confidence: 99%

Deriving physical parameters of unresolved star clusters

Meulenaer

Narbutis

Mineikis

et al. 2015

A&A

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Context. When trying to derive the star cluster physical parameters of the M 33 galaxy using broad-band unresolved ground-based photometry, previous studies mainly made use of simple stellar population models, shown in the recent years to be oversimplified. Aims. In this study, we aim to derive the star cluster physical parameters (age, mass, and extinction; metallicity is assumed to be LMC-like for clusters with age below 1 Gyr and left free for older clusters) of this galaxy using models that take stochastic dispersion of cluster integrated colors into account. Methods. We use three recently published M 33 catalogs of cluster optical broad-band photometry in standard UBVRI and in CFHT/MegaCam u * g r i z photometric systems. We also use near-infrared JHK photometry that we derive from deep 2MASS images. We derive the cluster parameters using a method that takes into account the stochasticity problem, presented in previous papers of this series. Results. The derived differential age distribution of the M 33 cluster population is composed of a two-slope profile indicating that the number of clusters decreases when age gets older. The first slope is interpreted as the evolutionary fading phase of the cluster magnitudes, and the second slope as the cluster disruption. The threshold between these two phases occurs at ∼300 Myr, comparable to what is observed in the M 31 galaxy. We also model by use of artificial clusters the ability of the cluster physical parameter derivation method to correctly derive the two-slope profile for different photometric systems tested.

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Section: Introductionmentioning

confidence: 99%

Deriving physical parameters of unresolved star clusters

Meulenaer

Narbutis

Mineikis

et al. 2015

A&A

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“…Two large spirals (the Milky Way and M 31) are the centers of two galaxy subgroupings, are only available in electronic form at http://www.aanda.org FITS files of the IRAM data are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/522/A3 each being surrounded by a large number of dwarf galaxies. In addition, M 31 -the Andromeda Galaxy -has a small spiral companion, M 33 (the Triangulum Galaxy); their separation is approximately 15 degrees, corresponding to 200 kpc (assuming a common distance of 840 kpc, Galleti et al 2004). Gaseous streams are observed between them, indicating tidal interaction (Putman et al 2009).…”

Section: Introductionmentioning

confidence: 99%

“…M 33 provides a means of observing a galaxy morphologically similar to our own but with a mass only a tenth of the Milky Way and factor two lower metallicity (Rosolowsky & Simon 2008;Magrini et al 2009). Further Galleti et al (2004); (b) HYPERLEDA (Paturel et al 2003); (c) Magrini et al (2009). evidence of the difference between M 33 and the Milky Way is the large gas fraction and blue stellar colors of the former relative to the latter. M 33 thus represents an environment in which to study the interstellar medium (ISM) and star formation (SF) that cannot be replaced by Galactic observations and where individual GMCs can be resolved to probe their SF activity.…”

Section: Introductionmentioning

confidence: 99%

Molecular and atomic gas in the Local Group galaxy M 33

Gratier

Braine

Rodríguez-Fernández

et al. 2010

A&A

147

154

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We present high-resolution large-scale observations of the molecular and atomic gas in the Local Group galaxy M 33. The observations were carried out using the HEterodyne Receiver Array (HERA) at the 30 m IRAM telescope in the CO(2-1) line, achieving a resolution of 12 × 2.6 km s −1 , enabling individual giant molecular clouds (GMCs) to be resolved. The observed region is 650 square arcminutes mainly along the major axis and out to a radius of 8.5 kpc, and covers entirely the 2 × 40 radial strip observed with the HIFI and PACS Spectrometers as part of the HERM33ES Herschel key program. The achieved sensitivity in main-beam temperature is 20-50 mK at 2.6 km s −1 velocity resolution. The CO(2-1) luminosity of the observed region is 1.7 ± 0.1 × 10 7 K km s −1 pc 2 and is estimated to be 2.8 ± 0.3 × 10 7 K km s −1 pc 2 for the entire galaxy, corresponding to H 2 masses of 1.9 × 10 8 M and 3.3 × 10 8 M respectively (including He), calculated with N(H 2 )/I CO(1−0) twice the Galactic value due to the half-solar metallicity of M 33. The H i 21 cm VLA archive observations were reduced, and the mosaic was imaged and cleaned using the multi-scale task in the CASA software package, yielding a series of datacubes with resolutions ranging from 5 to 25 . The H i mass within a radius of 8.5 kpc is estimated to be 1.4 × 10 9 M . The azimuthally averaged CO surface brightness decreases exponentially with a scale length of 1.9 ± 0.1 kpc whereas the atomic gas surface density is constant at Σ H i = 6± 2 M pc −2 deprojected to face-on. For an N(H 2 )/I CO(1−0) conversion factor twice that of the Milky Way, the central kiloparsec H 2 surface density is Σ H 2 = 8.5 ± 0.2 M pc −2 . The star formation rate per unit molecular gas (SF efficiency, the rate of transformation of molecular gas into stars), as traced by the ratio of CO to H α and FIR brightness, is constant with radius. The SFE, with a N(H 2 )/I CO(1−0) factor twice galactic, appears 2-4 times greater than for large spiral galaxies. A morphological comparison of molecular and atomic gas with tracers of star formation is presented showing good agreement between these maps both in terms of peaks and holes. A few exceptions are noted. Several spectra, including those of a molecular cloud situated more than 8 kpc from the galaxy center, are presented.

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“…(1) Stanek & Garnavich (1998); (2) Galleti et al (2004); (3) (2003); (11) Stanimirović et al (1999); (12) Chynoweth et al (2008); (13) Combes et al (1977); (14) Nieten et al (2006); (15) Fukui et al (2008); (16) Leroy et al (2007); (17) Mao et al (2000); (18) Houghton et al (1997); (19) in modelling the spectrum of the isotropic background component at energies >100 GeV. The fit suggests a hard power-law spectral index (Γ = 1.2 ± 0.4), which explains why the source is only seen at high energies.…”

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confidence: 99%

FermiLarge Area Telescope observations of Local Group galaxies: detection of M 31 and search for M 33

Abdo

Ackermann

Ajello

et al. 2010

A&A

188

234

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Context. Cosmic rays (CRs) can be studied through the galaxy-wide gamma-ray emission that they generate when propagating in the interstellar medium. The comparison of the diffuse signals from different systems may inform us about the key parameters in CR acceleration and transport. Aims. We aim to determine and compare the properties of the cosmic-ray-induced gamma-ray emission of several Local Group galaxies. Methods. We use 2 years of nearly continuous sky-survey observations obtained with the Large Area Telescope aboard the Fermi Gamma-ray Space Telescope to search for gamma-ray emission from M 31 and M 33. We compare the results with those for the Large Magellanic Cloud, the Small Magellanic Cloud, the Milky Way, and the starburst galaxies M 82 and NGC 253. Results. We detect a gamma-ray signal at 5σ significance in the energy range 200 MeV-20 GeV that is consistent with originating from M 31. The integral photon flux above 100 MeV amounts to (9.1 ± 1.9 stat ± 1.0 sys ) × 10 −9 ph cm −2 s −1 . We find no evidence for emission from M 33 and derive an upper limit on the photon flux >100 MeV of 5.1 × 10 −9 ph cm −2 s −1 (2σ). Comparing these results to the properties of other Local Group galaxies, we find indications of a correlation between star formation rate and gamma-ray luminosity that also holds for the starburst galaxies. Conclusions. The gamma-ray luminosity of M 31 is about half that of the Milky Way, which implies that the ratio between the average CR densities in M 31 and the Milky Way amounts to ξ = 0.35 ± 0.25. The observed correlation between gamma-ray luminosity and star formation rate suggests that the flux of M 33 is not far below the current upper limit from the LAT observations.

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The distance of M 33 and the stellar population in its outskirts

Cited by 98 publications

References 61 publications

Deriving physical parameters of unresolved star clusters

Deriving physical parameters of unresolved star clusters

Molecular and atomic gas in the Local Group galaxy M 33

FermiLarge Area Telescope observations of Local Group galaxies: detection of M 31 and search for M 33

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