Substellar Mass Function of Young Open Clusters as Determined through a Statistical Approach Using Two Micron All Sky Survey and Guide Star Catalog Data

Tej, Anandmayee; Sahu, Kailash C.; Chandrasekhar, T.; Ashok, N. M.

doi:10.1086/342425

Cited by 24 publications

(35 citation statements)

References 64 publications

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“…Using the median primary mass of 0.72 M , our result indicates a secondary-mass spectrum that is approximately flat down to 0.2 M and possibly higher between 0.07 and 0.2 M . This differs from the monotonic rise toward low masses found in the single-star initial mass functions (IMFs) of young open clusters (e.g., Barrado y Navascues et al Tej et al 2002;Moraux et al 2003) and the much younger starforming regions (Luhman et al 2000). It also differs from the lognormal IMF derived by Chabrier (2003) for the galactic field stars.…”

Section: Discussionmentioning

confidence: 83%

The Mass Ratio Distribution in Main‐Sequence Spectroscopic Binaries Measured by Infrared Spectroscopy

Mazeh¹,

Simon²,

Prato³

et al. 2003

ApJ

100

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We report infrared spectroscopic observations of a large well-defined sample of main-sequence, singlelined spectroscopic binaries to detect the secondaries and derive the mass ratio distribution of short-period binaries. The sample consists of 51 Galactic disk spectroscopic binaries found in the Carney and Latham high proper motion survey, with primary masses in the range 0.6-0.85 M . Our infrared observations detect the secondaries in 32 systems, two of which have mass ratios, q ¼ M 2 =M 1 , as low as $0.20. Together with 11 systems previously identified as double-lined binaries by visible light spectroscopy, we have a complete sample of 62 binaries, of which 43 are double lined. The mass ratio distribution is approximately constant over the range q ¼ 1:0-0.3. The distribution appears to rise at lower q values, but the uncertainties are sufficiently large that we cannot rule out a distribution that remains constant. The mass distribution derived for the secondaries in our sample and that of the extrasolar planets apparently represent two distinct populations.

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Section: Discussionmentioning

confidence: 83%

The Mass Ratio Distribution in Main‐Sequence Spectroscopic Binaries Measured by Infrared Spectroscopy

Mazeh¹,

Simon²,

Prato³

et al. 2003

ApJ

100

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“…Recent investigations have pointed out, however, that the fraction of young BDs relative to low-mass and more massive PMS stars may vary significantly among different star-forming regions (Kroupa 2002). In particular, the fraction in OB associations (Boulanger et al 1998;Hillenbrand & Carpenter 2000;Barrado y Navascués et al 2001;Briceño et al 2002;Muench et al 2002) exceeds that determined for T associations (Comerón et al 2000;Béjar et al 2001;Tej et al 2002;Briceño et al 2002;Spezzi et al 2007), suggesting that the environment may have an important impact on the BD formation process.…”

Section: Introductionmentioning

confidence: 99%

The Young Population of the Chamaeleon II Dark Cloud

Spezzi

Alcalá

Covino

et al. 2008

ApJ

187

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We discuss the results of the optical spectroscopic follow-up of preYmain-sequence ( PMS) objects and candidates selected in the Chamaeleon II dark cloud based on data from the Spitzer Legacy survey ''From Molecular Cores to Planet Forming Disks'' (c2d) and from previous surveys. Our sample includes both objects with infrared excess selected according to c2d criteria and referred to as young stellar objects and other cloud members and candidates selected from complementary optical and near-infrared data. We characterize the sample of objects by deriving their physical parameters. The vast majority of objects have masses M 1 M and ages <6 Myr. Several of the PMS objects and candidates lie very close to or below the hydrogen-burning limit. A first estimate of the slope of the initial mass function in Cha II is consistent with that of other T associations. The star formation efficiency in the cloud (1%Y4%) is consistent with our own estimates for Taurus and Lupus, but significantly lower than for Cha I. This might mean that different star formation activities in the Chamaeleon clouds may reflect a different history of star formation. We also find that the Cha II cloud is turning some 8 M into stars every megayear, which is less than the star formation rate in the other c2d clouds. However, the star formation rate is not steady and evidence is found that the star formation in Cha II might have occurred very rapidly. The H emission of the Cha II PMS objects, as well as possible correlations between their stellar and disk properties, is also investigated.

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“…This procedure was applied in Orionis, IC 348, and the Pleiades [62]. These studies are very useful to probe the large scale structure of clusters, determine globally their mass functions, and study possible variations radially.…”

Section: Wide-field Surveysmentioning

confidence: 99%

Brown dwarfs in wide-field surveys

Lodieu

2011

EPJ Web of Conferences

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Abstract. In this invited talk, I briefly summarise early photometric and proper motion surveys carried out in the nearest and youngest open clusters to introduce the motivation behind the Galactic Cluster component of the UKIRT Infrared Deep Sky Survey. Afterwards, I focus on the latest results that we obtained in the Upper Sco association and in the Pleiades. To finish, I show a comparison of the luminosity and mass functions obtained in the Upper Sco association, the Pleiades cluster, and Orionis from the homogeneous set of data publicly available from the Galactic Clusters Survey.

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Substellar Mass Function of Young Open Clusters as Determined through a Statistical Approach Using Two Micron All Sky Survey and Guide Star Catalog Data

Cited by 24 publications

References 64 publications

The Mass Ratio Distribution in Main‐Sequence Spectroscopic Binaries Measured by Infrared Spectroscopy

The Mass Ratio Distribution in Main‐Sequence Spectroscopic Binaries Measured by Infrared Spectroscopy

The Young Population of the Chamaeleon II Dark Cloud

Brown dwarfs in wide-field surveys

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