Giant Molecular Clouds in M33. I. BIMA All‐Disk Survey

Engargiola, G.; Plambeck, R. L.; Rosolowsky, Erik; Blitz, Leo

doi:10.1086/379165

Cited by 246 publications

(341 citation statements)

References 33 publications

(56 reference statements)

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“…17-19 are just a few among a huge number but are intended to show "special" positions. Figure 17 shows a very strong CO profile towards a region without strong star formation (note good agreement with Engargiola et al 2003). The line is very strong with a line width of about 11 km s −1 at half-intensity.…”

Section: Examples Of Interesting Spectrasupporting

confidence: 66%

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Molecular and atomic gas in the Local Group galaxy M 33

Gratier

Braine

Rodríguez-Fernández

et al. 2010

A&A

144

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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Section: Examples Of Interesting Spectrasupporting

confidence: 66%

“…This paper 0-7 1.9 ± 0.1 Gardan et al (2007) 2-6 1.4 ± 0.1 Engargiola et al (2003) 0-7 1.4 ± 0.1 Corbelli (2003) 0-6 2.5 "Lonely Cloud" by Gardan et al (2007). It is found in a region with very little if any star formation and relatively weak H i emission, despite fairly strong CO (and even 13 CO) emission.…”

Section: The Ism and Star Formation Tracersmentioning

confidence: 79%

Molecular and atomic gas in the Local Group galaxy M 33

Gratier

Braine

Rodríguez-Fernández

et al. 2010

A&A

144

154

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“…We used the 3-mm CO map of M 33 (J = 1-0 rotational line) obtained from the combination of the Berkeley Illinois Maryland Association (BIMA) array (Engargiola et al 2003;Rosolowsky et al 2007) and the Five College Radio Astronomy Observatory (FCRAO) single dish (Heyer et al 2004). The final resolution of the merged map is 13 .…”

Section: Co and Hi Mapsmentioning

confidence: 99%

Young stellar clusters and associations in M 33

Grossi

Corbelli

Giovanardi

et al. 2010

A&A

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Aims. We analyse multi-wavelength observations of 32 young star clusters and associations in M 33 with known oxygen abundance (8 < 12 + log(O/H) < 8.7). The data set includes ultraviolet (UV), optical, mid-infrared (MIR), CO (1-0) and 21-cm line (Hi) observations. We derive the spectral energy distribution (SED) of these systems and the properties of their gaseous environment to investigate the process of star formation and the interplay with the interstellar medium (ISM). Methods. We determine age, bolometric luminosities, masses, and the extinction by comparing the multi-band integrated photometry to single-age stellar population models. The best-fit solutions have been obtained using the Large Magellanic Cloud (LMC) extinction curves.Results. The stellar system ages range between 2 and 15 Myr, masses are between 3 × 10 2 and 4 × 10 4 M , and the intrinsic extinction, A V , varies from 0.3 to 1 mag. We find a correlation between age and extinction (young clusters being more reddened than older ones), and between the cluster mass and size. From the MIR emission we infer the presence of a dust component around the clusters whose fractional luminosity at 24 μm, L 24 /L Bol , decreases with the galactocentric distance. However, the total infrared luminosity inferred from L 24 is smaller than what we derive from the extinction corrections. We also find that the Hα luminosity predicted by population synthesis models is higher than the observed one, especially for low-mass systems (M < 10 4 M ). This difference is reduced, but not erased, when the incomplete sampling of the initial mass function (IMF) at the high-mass end is taken into account. Conclusions. Our results suggest that a non-negligible fraction of UV ionising and non-ionising radiation is leaking into the ISM outside the Hii regions. This agrees with the large UV and Hα diffuse fractions observed in M 33, but it implies that stellar systems younger than 3 Myr retain, on average, only 30% of their Lyman-continuum photons. However, the uncertainties in cluster ages and the stochastic fluctuations of the IMF do not allow us to accurately quantify this issue. We also consider the possibility that this discrepancy is the consequence of a suppressed or delayed formation of the most massive stars, given that it mainly affects the young and less massive clusters. We do not find any clear correlation between the cluster mass and the gas surface density or metallicity.

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“…We cross-correlated our source list with the following catalogs: The XMM-Newton survey of M33 (Pietsch et al 2004), the ROSAT source catalog (Haberl & Pietsch 2001), the catalog of SNRs by Gordon et al (1999), H ii regions from Hodge et al (1999), giant molecular clouds from Engargiola et al (2003), globular clusters from Mochejska et al (1998), star clusters from Chandar et al (1999Chandar et al ( , 2001, blue and red supergiants from Ivanov et al (1993), red supergiants from Massey (1998), WolfRayet stars from Massey & Johnson (1998), UV-bright stars from Massey et al (1996), hot stars from Massey et al (1995), OB associations from Regan & Wilson (1993), planetary nebulae from Magrini et al (2001), H emitters from Calzetti et al (1995), and the DIRECT star catalog from Macri et al (2001).…”

Section: Counterpartsmentioning

confidence: 99%

The X‐Ray Binary Population in M33. I. Source List and Luminosity Function

Grimm¹,

McDowell²,

Zezas³

et al. 2005

ASTROPHYS J SUPPL S

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In this paper we present the source list for three Chandra observations of the Local Group galaxy M33. The observations are centered on the nucleus and on the star-forming region NGC 604. We detect a total of 261 sources in an area of $0.2 deg 2 down to a flux limit of 3 ; 10 À16 ergs s À1 cm À2 , which corresponds to a luminosity of $2 ; 10 34 ergs s À1 at a distance of 840 kpc. From the source list we construct the luminosity functions of sources observed in M33. If we take into account background contamination, the luminosity functions are consistent with those of other star-forming galaxies. In addition, the combination of X-ray color analysis and the existence of ''blue'' optical counterparts strongly indicates that the X-ray point-source population in M33 consists of young objects. Above 3 ; 10 35 ergs s À1 there are few X-ray sources in the locus of the X-ray hardness ratio diagram that is generally populated by low-mass X-ray binaries.

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Giant Molecular Clouds in M33. I. BIMA All‐Disk Survey

Cited by 246 publications

References 33 publications

Molecular and atomic gas in the Local Group galaxy M 33

Molecular and atomic gas in the Local Group galaxy M 33

Young stellar clusters and associations in M 33

The X‐Ray Binary Population in M33. I. Source List and Luminosity Function

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