Stellar contents and star formation in the young open cluster Stock 8

Jose, Jessy; Pandey, A. K.; Ojha, D. K.; Ogura, K.; Chen, W.P.; Bhatt, B. C.; Ghosh, S. K.; Mito, Hiroyuki; Maheswar, G.; Sharma, Saurabh

doi:10.1111/j.1365-2966.2007.12825.x

Cited by 51 publications

(112 citation statements)

References 79 publications

(162 reference statements)

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“…For young open clusters (see, e.g. Devine et al 2008;Jose et al 2008, as an overview) the slopes α of the KLF lie between 0.3 and 0.4 in ranges of M K s between 0 and 3, whereas the slope of the KLF of CNS4 (see Fig. 3) is steeper, about 0.5, in the corresponding magnitude range.…”

Section: The Luminosity Functionmentioning

confidence: 99%

A deep all-sky census of the Hyades

Röser

Schilbach

Пискунов

et al. 2011

A&A

122

195

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Aims. On the basis of the PPMXL catalogue we perform an all-sky census of the Hyades down to masses of about 0.2 m in a region up to 30 pc from the cluster centre. Methods. We use the proper motions from PPMXL in the convergent point method to determine probable kinematic members. From 2MASS photometry and CMC14 r -band photometry, we derive empirical colour-absolute magnitude diagrams and, finally, determine photometric membership for all kinematic candidates. Results. This is the first deep (r ≤ 17) all-sky survey of the Hyades allowing a full three-dimensional analysis of the cluster. The survey is complete down to at least M Ks = 7.3 or 0.25 m . We find 724 stellar systems co-moving with the bulk Hyades space velocity, which represent a total mass of 435 m . The tidal radius is about 9 pc, and 275 m (364 systems) are gravitationally bound. This is the cluster proper. Its mass density profile is perfectly fitted by a Plummer model with a central density of 2.21 m pc −3 and a core radius of r co = 3.10 pc, while the half-mass radius is r h = 4.1 pc. There are another 100 m in a volume between one and two tidal radii (halo), and another 60 m up to a distance of 30 pc from the centre. Strong mass segregation is inherent in the cluster. The present-day luminosity and mass functions are noticeably different in various parts of the cluster (core, corona, halo, and co-movers). They are strongly evolved compared to presently favoured initial mass functions. The analysis of the velocity dispersion of the cluster shows that about 20% of its members must be binaries. As a by-product, we find that presently available theoretical isochrones are not able to adequately describe the near-infrared colour-absolute magnitude relation for those cluster stars that are less massive than about 0.6 m .

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Section: The Luminosity Functionmentioning

confidence: 99%

A deep all-sky census of the Hyades

Röser

Schilbach

Пискунов

et al. 2011

A&A

122

195

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“…The sources having X-ray emission and lying in the "F" region above the extension of the intrinsic CTTSs locus, as well as sources having (J − H) ≥ 0.6 mag and lying to the left of the first (leftmost) reddening vector (shown in Fig. 9) are assigned as WTTSs/Class III sources (see, e.g., Jose et al 2008;Pandey et al 2008;Sharma et al 2012). Here it is worthwhile to mention that some of the X-ray sources classified as WTTSs/Class III sources, lying near the middle reddening vector, could be CTTSs/ Class II sources.…”

Section: Classification Of X-ray Emitters Based On Nir Tcdmentioning

confidence: 99%

Investigation of the stellar content in the western part of the Carina nebula

Kumar¹,

Sharma²,

Manfroid³

et al. 2014

A&A

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Context. The low obscuration and proximity of the Carina nebula make it an ideal place to study the ongoing star formation process and impact of massive stars on low-mass stars in their surroundings. Aims. To investigate this process, we generated a new catalog of the pre-main-sequence stars in the Carina west (CrW) region and studied their nature and spatial distribution. We also determined various parameters (reddening, reddening law, age, mass), which are used further to estimate the initial mass function and K-band luminosity function for the region under study. Methods. We obtained deep UBVRI Hα photometric data of the field situated to the west of the main Carina nebula and centered on WR 22. Medium-resolution optical spectroscopy of a subsample of X-ray selected objects along with archival data sets from Chandra, XMM-Newton and 2MASS surveys were used for the present study. Different sets of color-color and color-magnitude diagrams are used to determine reddening for the region and to identify young stellar objects (YSOs) and estimate their age and mass. Results. Our spectroscopic results indicate that the majority of the X-ray sources are late spectral type stars. The region shows a large amount of differential reddening with minimum and maximum values of E(B − V) as 0.25 and 1.1 mag, respectively. Our analysis reveals that the total-to-selective absorption ratio R V is ∼3.7 ± 0.1, suggesting an abnormal grain size in the observed region. We identified 467 YSOs and studied their characteristics. The ages and masses of the 241 optically identified YSOs range from ∼0.1 to 10 Myr and ∼0.3 to 4.8 M , respectively. However, the majority of them are younger than 1 Myr and have masses below 2 M . The high mass star WR 22 does not seem to have contributed to the formation of YSOs in the CrW region. The initial mass function slope, Γ, in this region is found to be −1.13 ± 0.20 in the mass range of 0.5 < M/M < 4.8. The K-band luminosity function slope (α) is also estimated as 0.31 ± 0.01. We also performed minimum spanning tree analysis of the YSOs in this region, which reveals that there are at least ten YSO cores associated with the molecular cloud, and that leads to an average core radius of 0.43 pc and a median branch length of 0.28 pc.

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“…Given that the reddening law toward the neighboring clusters NGC 1893 and Stock 8 turned out to be normal (Jose et al 2008;Eswaraiah et al 2011;Lim et al 2014b), we assumed that the foreground reddening law in the direction of NGC 1931 was likely to be normal. In the lower panels of Figure 9, the color excess ratios of the members show a significant deviation from the normal reddening law.…”

Section: Reddening and The Reddening Lawmentioning

confidence: 99%

The Sejong Open Cluster Survey (Sos). Iv. The Young Open Clusters NGC 1624 and NGC 1931

Lim

Sung

Bessell

et al. 2015

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Young open clusters located in the outer Galaxy provide us with an opportunity to study star formation activity in a different environment from the solar neighborhood. We present a UBVI and Hα photometric study of the young open clusters NGC 1624 and NGC 1931 that are situated toward the Galactic anticenter. Various photometric diagrams are used to select the members of the clusters and to determine the fundamental parameters. NGC 1624 and NGC 1931 are, on average, reddened by E B V ( ) á -ñ = 0.92 ± 0.05 and 0.74 ± 0.17 mag, respectively. The properties of the reddening toward NGC 1931 indicate an abnormal reddening law (R V,cl = 5.2 ± 0.3). Using the zero-age main sequence fitting method we confirm that NGC 1624 is 6.0 ± 0.6 kpc away from the Sun, whereas NGC 1931 is at a distance of 2.3 ± 0.2 kpc. The results from isochrone fitting in the Hertzsprung-Russell diagram indicate the ages of NGC 1624 and NGC 1931 to be less than 4 and 1.5-2.0 Myr, respectively. We derived the initial mass function (IMF) of the clusters. The slope of the IMF ( NGC 1624 G = −2.0 ± 0.2 and NGC 1931 G = −2.0 ± 0.1) appears to be steeper than that of the Salpeter/Kroupa IMF. We discuss the implication of the derived IMF based on simple Monte-Carlo simulations and conclude that the property of star formation in the clusters does not seem to be significantly different from that in the solar neighborhood.

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Stellar contents and star formation in the young open cluster Stock 8

Cited by 51 publications

References 79 publications

A deep all-sky census of the Hyades

A deep all-sky census of the Hyades

Investigation of the stellar content in the western part of the Carina nebula

The Sejong Open Cluster Survey (Sos). Iv. The Young Open Clusters NGC 1624 and NGC 1931

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