- ID:
- ivo://CDS.VizieR/J/AJ/150/95
- Title:
- Masses and ages of YSOs in Per OB2
- Short Name:
- J/AJ/150/95
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have performed a Wide-Field Infrared Survey Explorer based study to identify and characterize young stellar objects (YSOs) in the 12{deg}x12{deg} Perseus OB2 association. A spectral energy distribution (SED) slope in the range of 3.4-12{mu}m and 5{sigma} selection criteria were used to select our initial sample. Further manual inspection reduced our final catalog to 156 known and 119 YSO candidates. The spatial distribution of newly found YSOs all over the field shows an older generation of star formation in which most of its massive members have evolved into main-sequence stars. In contrast, the majority of younger members lie within the Perseus molecular cloud and currently active star-forming clusters such as NGC 1333 and IC 348. We also identified an additional 66 point sources that passed YSO selection criteria but are likely AGB stars. However, their spatial distribution suggests that they may contain a fraction of the YSOs. Comparing our results with the commonly used color-color selections, we found that while the color selection method fails in picking up bright but evolved weak disks, our SED fitting method can identify such sources, including transitional disks. In addition, we have less contamination with background sources such as galaxies, but at a price of losing fainter (J_mag_>12) YSOs. Finally, we employed a Bayesian Monte Carlo SED fitting method to determine the characteristics of each YSO candidate. Distribution of SED slopes and model-driven age and mass confirms separated YSO populations with three suggested age groups of younger than 1Myr old, 1-5Myr old, and older than 5Myr, which agrees with the age of the Per OB2 association and currently star-forming sites within the cloud.
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Search Results
- ID:
- ivo://CDS.VizieR/J/AJ/149/56
- Title:
- Masses and photometry of 304 M31 old star clusters
- Short Name:
- J/AJ/149/56
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This paper presents CCD multicolor photometry for 304 old star clusters in the nearby spiral galaxy M31, from which the photometry of 55 star clusters is first obtained. The observations were carried out as a part of the Beijing-Arizona-Taiwan-Connecticut Multicolor Sky Survey from 1995 February to 2008 March, using 15 intermediate-band filters covering 3000-10000{AA}. Detailed comparisons show that our photometry is in agreement with previous measurements. Based on the ages and metallicities from Caldwell et al. and the photometric measurements here, we estimated the clusters' masses by comparing their multicolor photometry with stellar population synthesis models. The results show that the sample clusters have masses between ~3x10^4^M_{sun}_ and ~10^7^M_{sun}_ with a peak of ~4x10^5^_M{sun}_. The masses here are in good agreement with those in previous studies. Combined with the masses of young star clusters of M31 from Wang et al., we find that the peak mass of the old clusters is 10 times that of young clusters.
- ID:
- ivo://CDS.VizieR/J/A+A/404/223
- Title:
- 2MASS IR star clusters in the Galaxy
- Short Name:
- J/A+A/404/223
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We carried out a survey of infrared star clusters and stellar groups on the 2MASS J, H and Ks all-sky release Atlas in the Northern and Equatorial Milky Way (350{deg},l<360{deg}, 0{deg}<l<230{deg}). The search in this zone complements that in the Southern Milky Way (Dutra et al., 2003, Cat. <J/A+A/400/533>). The method concentrates efforts on the directions of known optical and radio nebulae. The present study provides 167 new infrared clusters, stellar groups and candidates. Combining the two studies for the whole Milky Way, 346 infrared clusters, stellar groups and candidates were discovered, whereas 315 objects were previously known. They constitute an important new sample for future detailed studies.
- ID:
- ivo://CDS.VizieR/J/AJ/149/26
- Title:
- Massive binary stars from an HST/FGS survey
- Short Name:
- J/AJ/149/26
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of an all-sky survey made with the Fine Guidance Sensor on the Hubble Space Telescope to search for angularly resolved binary systems among massive stars. The sample of 224 stars is comprised mainly of Galactic O- and B-type stars and luminous blue variables, plus a few luminous stars in the Large Magellanic Cloud. The FGS TRANS mode observations are sensitive to the detection of companions with an angular separation between 0.01'' and 1.0'' and brighter than {delta}m=5. The FGS observations resolved 52 binary and 6 triple star systems and detected partially resolved binaries in 7 additional targets (43 of these are new detections). These numbers yield a companion detection frequency of 29% for the FGS survey. We also gathered literature results on the numbers of close spectroscopic binaries and wider astrometric binaries among the sample, and we present estimates of the frequency of multiple systems and the companion frequency for subsets of stars residing in clusters and associations, field stars, and runaway stars. These results confirm the high multiplicity fraction, especially among massive stars in clusters and associations. We show that the period distribution is approximately flat in increments of logP. We identify a number of systems of potential interest for long-term orbital determinations, and we note the importance of some of these companions for the interpretation of the radial velocities and light curves of close binaries that have third companions.
- ID:
- ivo://CDS.VizieR/J/A+A/600/L10
- Title:
- Massive cluster progenitors from ATLASGAL
- Short Name:
- J/A+A/600/L10
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The early evolution of massive cluster progenitors is poorly understood. We investigate the fragmentation properties from 0.3pc to 0.06pc scales of a homogenous sample of infrared-quiet massive clumps within 4.5kpc selected from the ATLASGAL survey. Using the ALMA 7m array we detect compact dust continuum emission towards all targets and find that fragmentation, at these scales, is limited. The mass distribution of the fragments uncovers a large fraction of cores above 40M_{sun}_, corresponding to massive dense cores (MDCs) with masses up to ~400M_{sun}_. Seventy-seven percent of the clumps contain at most 3 MDCs per clump, and we also reveal single clumps/MDCs. The most massive cores are formed within the more massive clumps and a high concentration of mass on small scales reveals a high core formation efficiency. The mass of MDCs highly exceeds the local thermal Jeans mass, and we lack the observational evidence of a survey efficiently high level of turbulence or strong enough magnetic fields to keep the most massive MDCs in equilibrium. If already collapsing, the observed fragmentation properties with a high core formation efficiency are consistent with the collapse setting in at parsec scales.
- ID:
- ivo://CDS.VizieR/J/MNRAS/430/676
- Title:
- Massive clusters in the LMC
- Short Name:
- J/MNRAS/430/676
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Large Magellanic Cloud (LMC) is one of the nearest galaxies to us and is one of only few galaxies where the star formation history can be determined from studying resolved stellar populations. We have compiled a new catalogue of ages, luminosities and masses of LMC star clusters and used it to determine the age distribution and dissolution rate of LMC star clusters. We find that the frequency of massive clusters with masses M>5000M_{sun}_ is almost constant between 10 and 200Myr, showing that the influence of residual gas expulsion is limited to the first 10Myr of cluster evolution or clusters less massive than 5000M_{sun}_.
- ID:
- ivo://CDS.VizieR/J/AJ/101/1408
- Title:
- Massive stars in Cyg OB2.
- Short Name:
- J/AJ/101/1408
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The galactic association Cygnus OB2, which contains heavily reddened O and B stars, has been studied using CCD UBV photometry and spectroscopy. The file "mt91.dat" contains precise coordinates, UBV photometry, and spectral types from the study of Cygnus OB2, and merges the tables 2, 5 and 6 from the paper.
- ID:
- ivo://CDS.VizieR/J/A+A/626/A50
- Title:
- Massive stars in NGC 346
- Short Name:
- J/A+A/626/A50
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Spectroscopy for 247 stars towards the young cluster NGC 346 in the Small Magellanic Cloud has been combined with that for 116 targets from the VLT-FLAMES Survey of Massive Stars. Spectral classification yields a sample of 47 O-type and 287 B-type spectra, while radial-velocity variations and/or spectral multiplicity have been used to identify 45 candidate single-lined (SB1) systems, 17 double-lined (SB2) systems, and one triple-lined (SB3) system. Atmospheric parameters (T_eff_ and log g) and projected rotational velocities (v_e_sini) have been estimated usingTLUSTY model atmospheres; independent estimates of v_e_sini were also obtained using a Fourier Transform method. Luminosities have been inferred from stellar apparent magnitudes and used in conjunction with the T_eff_ and v_e_sini estimates to constrain stellar masses and ages using theBONNSAI package. We find that targets towards the inner region of NGC 346 have higher median masses and projected rotational velocities, together with smaller median ages than the rest of the sample. There appears to be a population of very young targets with ages of less than 2Myr, which have presumably all formed within the cluster. The more massive targets are found to have lower projected rotational velocities consistent with previous studies. No significant evidence is found for differences with metallicity in the stellar rotational velocities of early-type stars, although the targets in the Small Magellanic Cloud may rotate faster than those in young Galactic clusters. The rotational velocity distribution for single non-supergiant B-type stars is inferred and implies that a significant number have low rotational velocity (~=10% with v_e_<40km/s), together with a peak in the probability distribution at v_e_~=300km/s. Larger projected rotational velocity estimates have been found for our Be-type sample and imply that most have rotational velocities between 200-450km/s.
- ID:
- ivo://CDS.VizieR/J/ApJ/662/413
- Title:
- 2MASS survey of wide multiplicity in 3 associations
- Short Name:
- J/ApJ/662/413
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a search for wide binary systems among 783 members of three nearby young associations: Taurus-Auriga, Chamaeleon I, and two subgroups of Upper Scorpius. Near-infrared (JHK) imagery from 2MASS was analyzed to search for wide (1"-30"; ~150-4500AU) companions to known association members, using color-magnitude cuts to reject likely background stars. We identify a total of 131 candidate binary companions with colors consistent with physical association, of which 39 have not been identified previously in the literature.
- ID:
- ivo://CDS.VizieR/J/ApJS/91/583
- Title:
- MC massive stars IMF. I.
- Short Name:
- J/ApJS/91/583
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- UBV CCD photometry has been obtained for 14 OB associations in the Magellanic Clouds using the University of Toronto's 0.6m telescope and the Carnegie Institution of Washington's 1.0m reflector, both on Las Campanas, Chile. The data are presented and used to construct color-magnitude diagrams for the purposes of investigating the massive-star content of the associations.
