Massive Stellar Content of Giant H<scp>ii</scp>Regions in M33 and M101

Pellerin, Anne

doi:10.1086/499073

Cited by 22 publications

(33 citation statements)

References 58 publications

(155 reference statements)

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“…Jamet et al do warn, however, that stochastic sampling of the IMF can cause deviations in the integrated properties of the OB-associations, given their relatively low masses. This was also found by Pellerin (2006) for five Hii regions in M33, which were best fit with slightly flatter IMFs when fit with standard population synthesis models, but were consistent with a Salpeter slope when stochasticity was taken into account. We will return to the use of UV spectral features to constrain the IMF in § 3.2.4 and § 4.1.1 where these techniques have been applied to local and high redshift starburst galaxies, respectively.…”

Section: The Local Groupsupporting

confidence: 76%

“…Gonzalez Delgado et al 1997;Leitherer et al 1999;Maraston et al 2009). Nearby starburst galaxies also have UV spectral diagnostics that are consistent with a Salpeter distribution of high mass stars (see reviews Pellerin &Robert 2007 andLeitherer 2009). Tremonti et al (2001) have studied the UV spectral properties across the actively star forming galaxy NGC 5253, focussing mainly on the difference between the spectra of "clusters" and "the field".…”

Section: Hα Uv and Infrared Studies Of Integrated Stellar Populationsmentioning

confidence: 92%

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A Universal Stellar Initial Mass Function? A Critical Look at Variations

Bastian

Covey

Meyer

2010

Annu. Rev. Astron. Astrophys.

933

453

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Few topics in astronomy initiate such vigorous discussion as whether or not the initial mass function (IMF) of stars is universal, or instead sensitive to the initial conditions of star formation. The distinction is of critical importance: the IMF influences most of the observable properties of stellar populations and galaxies, and detecting variations in the IMF could provide deep insights into the process by which stars form. In this review, we take a critical look at the case for IMF variations, with a view towards whether other explanations are sufficient given the evidence. Studies of the field, local young clusters and associations, and old globular clusters suggest that the vast majority were drawn from a "universal" IMF: a power-law of Salpeter index (Γ = 1.35) above a few solar masses, and a log normal or shallower power-law (Γ ∼ 0 − 0.25) between a few tenths and a few solar masses (ignoring the effects of unresolved binaries). The shape and universality of the IMF at the stellar-substellar boundary is still under investigation and uncertainties remain large, but most observations are consistent with a IMF that declines (Γ < −0.5) well below the hydrogen burning limit. Observations of resolved stellar populations and the integrated properties of most galaxies are also consistent with a "universal IMF", suggesting no gross variations in the IMF over much of cosmic time. There are indications of "non-standard" IMFs in specific local and extragalactic environments, which clearly warrant further study. Nonetheless, there is no clear evidence that the IMF varies strongly and systematically as a function of initial conditions after the first few generations of stars. We close with suggestions for future work that might uncover more subtle IMF variations than those that could be discerned to date.

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Section: The Local Groupsupporting

confidence: 76%

Section: Hα Uv and Infrared Studies Of Integrated Stellar Populationsmentioning

confidence: 92%

A Universal Stellar Initial Mass Function? A Critical Look at Variations

Bastian

Covey

Meyer

2010

Annu. Rev. Astron. Astrophys.

933

453

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“…In other cases, we observe a mismatch between the properties of the system inferred from observations of their individual components and those derived from their integrated properties analyzed with synthesis models: e.g. the discrepancy between the age determined from the color-magnitude diagram and the spectroscopic age in NGC 588 (Jamet et al 2004), or the IMF slope inferred by Pellerin (2006) in undersampled giant H ii regions. In these cases, we are facing a crisis in the explanatory power of synthesis models.…”

Section: Introductionmentioning

confidence: 80%

Confidence limits of evolutionary synthesis models

Cerviño¹,

Luridiana²

2006

A&A

100

136

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Context. Synthesis models predict the integrated properties of stellar populations. Several problems exist in this field, mostly related to the fact that integrated properties are distributed. To date, this aspect has been either ignored (as in standard synthesis models, which are inherently deterministic) or interpreted phenomenologically (as in Monte Carlo simulations, which describe distributed properties rather than explain them). Aims. This paper presents a method of population synthesis that accounts for the distributed nature of stellar properties. Methods. We approach population synthesis as a problem in probability theory, in which stellar luminosities are random variables extracted from the stellar luminosity distribution function (sLDF). Results. With standard distribution theory, we derive the population LDF (pLDF) for clusters of any size from the sLDF, obtaining the scale relations that link the sLDF to the pLDF. We recover the predictions of standard synthesis models, which are shown to compute the mean of the luminosity function. We provide diagnostic diagrams and a simplified recipe for testing the statistical richness of observed clusters, thereby assessing whether standard synthesis models can be safely used or a statistical treatment is mandatory. We also recover the predictions of Monte Carlo simulations, with the additional bonus of being able to interpret them in mathematical and physical terms. We give examples of problems that can be addressed through our probabilistic formalism: calibrating the SBF method, determining the luminosity function of globular clusters, comparing different isochrone sets, tracing the sLDF by means of resolved data, including fuzzy stellar properties in population synthesis, among others. Additionally, the algorithmic nature of our method makes it suitable for developing analysis tools for the Virtual Observatory. Conclusions. Though still under development, ours is a powerful approach to population synthesis. In an era of resolved observations and pipelined analyses of large surveys, this paper is offered as a signpost in the field of stellar populations.

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“…It is a young star forming region with an age of 3-5 Myr (e.g., Wilson & Matthews 1995;Pellerin 2006). Located some 12…”

Section: Spitzer Mid-ir Variability Surveymentioning

confidence: 99%

The UK Infrared Telescope M33 monitoring project – IV. Variable red giant stars across the galactic disc

Javadi

Saberi

Loon

et al. 2015

Monthly Notices of the Royal Astronomical Society

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We have conducted a near-infrared monitoring campaign at the UK InfraRed Telescope (UKIRT), of the Local Group spiral galaxy M 33 (Triangulum). The main aim was to identify stars in the very final stage of their evolution, and for which the luminosity is more directly related to the birth mass than the more numerous less-evolved giant stars that continue to increase in luminosity. In this fourth paper of the series, we present a search for variable red giant stars in an almost square degree region comprising most of the galaxy's disc, carried out with the WFCAM instrument in the K band. These data, taken during the period 2005-2007, were complemented by J-and H-band images. Photometry was obtained for 403 734 stars in this region; of these, 4643 stars were found to be variable, most of which are Asymptotic Giant Branch (AGB) stars. The variable stars are concentrated towards the centre of M 33, more so than low-mass, less-evolved red giants. Our data were matched to optical catalogues of variable stars and carbon stars and to mid-infrared photometry from the Spitzer Space Telescope. Most dusty AGB stars had not been previously identified in optical variability surveys, and our survey is also more complete for these types of stars than the Spitzer survey. The photometric catalogue is made publicly available at the Centre de Données astronomiques de Strasbourg.

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Massive Stellar Content of Giant HiiRegions in M33 and M101

Cited by 22 publications

References 58 publications

A Universal Stellar Initial Mass Function? A Critical Look at Variations

A Universal Stellar Initial Mass Function? A Critical Look at Variations

Confidence limits of evolutionary synthesis models

The UK Infrared Telescope M33 monitoring project – IV. Variable red giant stars across the galactic disc

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