Stellar contents of two young open clusters: NGC 663 and 654

Pandey, A. K.; Upadhyay, K.; Ogura, K.; Sagar, Ram; Mohan, V.; Mito, Hiroyuki; Bhatt, H. C.; Bhatt, B. C.

doi:10.1111/j.1365-2966.2005.08784.x

Cited by 47 publications

(95 citation statements)

References 46 publications

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“…Our estimates of the radii of the clusters are larger than that of the values given by Dias et al (2002) using optical data except for the open cluster Berkeley 86. However, these values are consistent with the values given by Pandey et al (2005) and Currie et al (2010) in the case of NGC 663 and NGC 869, respectively. It is not possible to define the cluster extent in the case of IC 2602 and Trumpler 18 because the boundary where the stellar densities merge into field star densities is not clearly marked in the radial density profiles.…”

Section: Center and Radius Of The Clusterssupporting

confidence: 90%

X-ray Observations of Eight Young Open Star Clusters: I. Membership and X-ray Luminosity

et al. 2013

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Abstract. We present a detailed investigation of X-ray source contents of eight young open clusters with ages between 4 to 46 Myr using archival X-ray data from XMM-Newton. The probable cluster memberships of the X-ray sources have been established on the basis of multi-wavelength archival data, and samples of 152 pre-main sequence (PMS) low mass (< 2 M ⊙ ), 36 intermediate mass (2 -10 M ⊙ ) and 16 massive (> 10 M ⊙ ) stars have been generated. X-ray spectral analyses of high mass stars reveal the presence of high temperature plasma with temperature <2 keV, and mean L X /L bol of 10 −6.9 . In the case of PMS low mass stars, the plasma temperatures have been found to be in the range of 0.2 keV to 3 keV with a median value of ∼1.3 keV, with no significant difference in plasma temperatures during their evolution from 4 to 46 Myr. The X-ray luminosity distributions of the PMS low mass stars have been found to be similar in the young star clusters under study. This may suggest a nearly uniform X-ray activity in the PMS low mass stars of ages ∼4 -14 Myr. These observed values of L X /L bol are found to have a mean value of 10 −3.6±0.4 , which is below the X-ray saturation level.The L X /L bol values for the PMS low mass stars are well correlated with their bolometric luminosities, that implies its dependence on the internal structure of the low mass stars. The difference between the X-ray luminosity distributions of the intermediate mass stars and the PMS low mass stars has not been found to be statistically significant. Their L X /L bol values, however have been found to be significantly different from each other with a confidence level greater than 99.999% and the strength of Xray activity in the intermediate mass stars is found to be lower compared to the low mass stars. However, the possibility of Xray emission from the intermediate mass stars due to a low mass

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Section: Center and Radius Of The Clusterssupporting

confidence: 90%

X-ray Observations of Eight Young Open Star Clusters: I. Membership and X-ray Luminosity

et al. 2013

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“…Although the average slope of the MF does not seem to be very different from the Salpeter (1955) value, Pandey et al (2001Pandey et al ( , 2005 found that the nature of the MF in open clusters does not remain the same over the entire region of the cluster and the slope of the MF steepens as radial distance from the cluster center increases.…”

Section: Introductionmentioning

confidence: 92%

“…We used V /(V − I ) CMD to estimate the membership as well as the LF of the cluster. The contamination due to field stars is greatly reduced by selecting a sample of stars which are located near the well-defined MS as described by Pandey et al (2001Pandey et al ( , 2005. The same envelopes were used for the V /(V −I ) CMD of the field region to estimate the contamination in the cluster region due to field stars.…”

Section: Probable Members and Data Incompletenessmentioning

confidence: 99%

Mass Functions and Photometric Binaries in Nine Open Clusters

Sharma

Pandey

Ogura

et al. 2008

The Astronomical Journal

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Using homogeneous CCD photometric data from the 105 cm Kiso Schmidt telescope covering a 50 × 50 field, we study the mass functions (MFs) of nine open clusters. The ages and Galactocentric distances of the target clusters vary from 16-2000 Myr and 9-10.8 kpc, respectively. The values of MF slopes vary from −1.1 to −2.1. The classical value derived by Salpeter in 1955 for the slope of the initial mass function (IMF) is Γ = −1.35. The MFs in the outer regions of the clusters are found to be steeper than in the inner regions, indicating the presence of mass segregation in the clusters. The MF slopes (in the outer region as well as the whole cluster) undergo an exponential decay with the evolutionary parameter τ (=age/relaxation time). It seems that the evaporation of low-mass members from outer regions of the clusters is not significant at larger Galactocentric distances. It is concluded that IMF in the anti-center direction of the Galaxy might have been steeper than the IMF in the opposite direction. A comparison of the observed color-magnitude diagrams (CMDs) of the clusters with synthetic CMDs gives a photometric binary content of ∼40%.

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“…A main piece of information to understand the star-formation process is the stellar mass distribution that results from the fragmentation of molecular clouds. Whether it is universal or depends on local environments, initial mass, or luminosity functions of a young cluster can be used to address important questions about the star-formation process (e.g., Pandey et al 2005). Young embedded clusters, in particular, Based on observations collected at the ESO 8.2-m VLT-UT1 Antu telescope (program 66.C-0015A).…”

Section: Introductionmentioning

confidence: 99%

Molecular gas and a new young stellar cluster in the far outer Galaxy

Yun

Elia

Palmeirim

et al. 2009

A&A

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Aims. We investigate the star-formation ocurring in the region towards IRAS 07527-3446 in the molecular cloud [MAB97]250. 63-3.63, in the far outer Galaxy. We report the discovery of a new young stellar cluster, and describe its properties and those of its parent molecular cloud. Methods. Near-infrared JHK S images were obtained with VLT/ISAAC, and millimetre line CO spectra were obtained with the SEST telescope. VLA archive date were also used. Results. The cloud and cluster are located at a distance of 10.3 kpc and a Galactocentric distance of 15.4 kpc, in the far outer Galaxy. Morphologically, IRAS 07527-3446 appears as a young embedded cluster of a few hundred stars seen towards the position of the IRAS source, extending for about 2-4 pc and exhibiting sub-clustering. The cluster contains low and intermediate-mass young reddened stars, a large fraction having cleared the inner regions of their circumstellar discs responsible for (H − K S ) colour excess. The observations are compatible with a ≤5 Myr cluster with variable spatial extinction of between A V = 5 and A V = 11. Decomposition of CO emission in clumps, reveals a clump clearly associated with the cluster position, of mass 3.3 × 10 3 M . Estimates of the slopes of the K S -band luminosity function and of the star-formation efficiency yield values similar to those seen in nearby star-formation sites. These findings reinforce previous results that the distant outer Galaxy continues to be active in the production of new and rich stellar clusters, with the physical conditions required for the formation of rich clusters continuing to be met in the very distant environment of the outer Galactic disc.

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Stellar contents of two young open clusters: NGC 663 and 654

Cited by 47 publications

References 46 publications

X-ray Observations of Eight Young Open Star Clusters: I. Membership and X-ray Luminosity

X-ray Observations of Eight Young Open Star Clusters: I. Membership and X-ray Luminosity

Mass Functions and Photometric Binaries in Nine Open Clusters

Molecular gas and a new young stellar cluster in the far outer Galaxy

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