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- ID:
- ivo://CDS.VizieR/J/A+A/361/660
- Title:
- JHK photometry around S233IR
- Short Name:
- J/A+A/361/660
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Observed properties of sources in the region S233IR in a field of 3.1 arcmin by 3.1 arcmin, which contains two young stellar clusters located to the northeast (NE) and southwest (SW) of the field center (RA = 05 35 49.79, DE = +35 44 01.9). Source positions, JHK photometry, extinction and estimated stellar mass are provided.
- ID:
- ivo://CDS.VizieR/J/PASP/120/150
- Title:
- JHK photometry in Cluster [BDS2003] 107
- Short Name:
- J/PASP/120/150
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new near-infrared classification spectra for nine candidate members of the galactic cluster [BDS2003] 107 (Cluster 107) observed with the IRTF SpeX instrument. We can spectroscopically classify at least three members, two of which have published 2MASS photometry. These two stars provide preliminary values for the approximate age (10^6^yr), distance (<=2kpc), and extinction (A_V_~23) of the young cluster. Based on the properties of the brightest members we have identified, on the surface Cluster 107 appears to be very similar to the well-studied Orion cluster. We find a single mid-O dwarf star and a number of early-B stars, along with massive young stellar objects (YSOs) in the field. The massive YSO Star 63 shows simultaneously an early-B spectral classification in the short K-band with CO band-head emission at 2.3um. This massive YSO looks similar to other luminous CO emission objects seen in young, massive clusters through out the Galaxy and provides additional evidence for the existence of circumstellar disks around even fairly massive stars. Several previously identified radio sources, presumably associated with very early star formation, lie within this field, three of which appear to have near-infrared counterparts as detected in images we obtained with the SpeX acquisition camera.
- ID:
- ivo://CDS.VizieR/J/MNRAS/390/1185
- Title:
- JHK photometry in 2 star-forming regions
- Short Name:
- J/MNRAS/390/1185
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- IRAS 21413+5442 and IRAS 21407+5441 are two massive star-forming regions of high luminosity, likely associated with each other. Near-infrared (NIR) photometry on these two IRAS sources was performed at United Kingdom Infrared Telescope (UKIRT) using the UFTI under excellent seeing conditions yielding an angular resolution of ~0.5arcsec. Our results reveal details of stellar content to a completeness limit (90 per cent) of J=18.5, H=18.0 and K=17.5mag in the two regions. In IRAS 21413+5442, we identify a late O-type star, having large H-K colour, to be near the centre of the CO jets observed by earlier authors. The UKIRT images reveal in IRAS 21407+5441, a faint but clear compact HII region around a central high- and intermediate-mass star cluster. We have detected a number of sources with large H-K colour which are not detected in J band. We also present the GMRT radio continuum map at 1.28GHz covering the entire region surrounding the two star-forming clouds.
- ID:
- ivo://CDS.VizieR/J/A+A/525/A1
- Title:
- JHK photometry of CBJC 8 sources
- Short Name:
- J/A+A/525/A1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The infrared cluster CBJC 8 is associated with a 6.7GHz methanol maser and a compact radio-continuum source, G85.40-0.00. It is located at a distance of about 8kpc. The aim is to study the characteristics of this distant and compact embedded cluster and derive the properties of its stellar population. We present new ground-based near- and mid-imaging observations of this region. The calibrated images were analysed together with archive Spitzer IRAC images. Based on the discovery of a considerable fraction of embedded sources with infrared excess emission that are concentrated within a radius around 16arcsec centred near the position of the compact HII region G85.40-0.00, we were able to confirm the presence of a very young embedded cluster. It was found to contain more than 58 members brighter than M_K_=2.6, with two-thirds of them showing significant near- or mid-IR excess emission. Spectral energy distributions and extrapolated total luminosities are presented for nine sources with large mid-infrared excesses that were measured in all four IRAC bands. For the brightest of these, G8540A, which is associated with a methanol maser and a compact HII region, we fitted a model of an infalling envelope plus disc plus central star to its observed 1.6 to 850um fluxes to get an idea of its physical properties. We also report the presence of a single 2.12um molecular hydrogen line emission knot near the centre of the cluster, suggesting the outflow activity.
- ID:
- ivo://CDS.VizieR/J/ApJS/118/177
- Title:
- JHK photometry of M31 spiral arm
- Short Name:
- J/ApJS/118/177
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Deep high-resolution JHK images of a 2'x2' field around the OB association A24 near the 7kpc spiral arm in M31 were measured to yield photometric data of more than 3000 stars with the faintest magnitude being J=21.3, H=20.5, and K=19.6. The photometric data for the 1037 stars that are brightest in the K band are presented. Judging from the color-magnitude and the two-color diagrams, we find that the majority of the observed stars are AGB stars including large-amplitude variables. They are distributed smoothly over the observed field, and we find no clear evidence of varying extinction over the field for these red stars. The present sample includes bright AGB stars of M_K_<=-8 and about 30 young blue objects of (J-H)<0.75 that are brighter than M_J_~=-6.5.
- ID:
- ivo://CDS.VizieR/J/AJ/126/1916
- Title:
- JHK photometry of young clusters near the Sun
- Short Name:
- J/AJ/126/1916
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalog of near-infrared surveys of young (<~a few 10^6^yr) stellar groups and clusters within 1kpc from the Sun, based on an extensive search of the literature from the past ten years. We find 143 surveys from 69 published articles, covering 73 different regions. The number distribution of stars in a region has a median of 28 and a mean of 100. About 80% of the stars are in clusters with at least 100 members. By a rough classification of the groups and clusters based on the number of their associated stars, we show that most of the stars form in large clusters. The spatial distribution of catalogued regions in the Galactic plane shows a relative lack of observed stellar groups and clusters in the range 270{deg}<l<60{deg} of Galactic longitude, reflecting our location between the Local and Sagittarius arms. This compilation is intended as a useful resource for future studies of nearby young regions of multiple star formation.
- ID:
- ivo://CDS.VizieR/J/MNRAS/355/1237
- Title:
- JHKs photometry of G287.84-0.82 members
- Short Name:
- J/MNRAS/355/1237
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have studied the properties of an infrared cluster embedded in the gas and dust of the southern part of the Carina nebula (NGC 3372), where the probable existence of current star formation has already been predicted. We used mid-infrared (A and C bands) and near-infrared (JHKs) images from the Midcourse Space Experiment and the Two-Micron All-Sky Survey, respectively, combined with an optical H{alpha} narrow-band filter image obtained at the Cerro Tololo Inter-American Observatory. The infrared star cluster has at least 17 members, and its parameters, radius and stellar density are in very good agreement with high- to intermediate-mass star formation scenarios. The detected infrared sources have roughly the same intrinsic infrared excess determined from their position in colour-colour and colour-magnitude diagrams, suggesting that these objects could be related to pre-main-sequence stars of high to intermediate mass. Furthermore, we present a low-dispersion spectrum of the LS 1883 (O9.5V) star located near the centre of the infrared cluster. The position of this object in the colour-colour and colour-magnitude infrared diagrams lies close to the reddening vector of a zero-age main-sequence O9V spectral-type star, and it seems to be the first star of this cluster to emerge. All these facts are consistent with the current star-forming scenarios associated with highly embedded star clusters.
- ID:
- ivo://CDS.VizieR/J/AJ/156/71
- Title:
- K2 Campaign 2: young disk-bearing stars in Sco & Oph
- Short Name:
- J/AJ/156/71
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The K2 Mission has photometrically monitored thousands of stars at high precision and cadence in a series of ~80-day campaigns focused on sections of the ecliptic plane. During its second campaign, K2 targeted over 1000 young stellar objects (YSOs) in the ~1-3 Myr {rho} Ophiuchus and 5-10 Myr Upper Scorpius regions. From this set, we have carefully vetted photometry from WISE and Spitzer to identify those YSOs with infrared excess indicative of primordial circumstellar disks. We present here the resulting comprehensive sample of 288 young disk-bearing stars from B through M spectral types and analysis of their associated K2 light curves. Using statistics of periodicity and symmetry, we categorize each light curve into eight different variability classes, notably including "dippers" (fading events), "bursters" (brightening events), stochastic, and quasi-periodic types. Nearly all (96%) of disk-bearing YSOs are identified as variable at 30-minute cadence with the sub-1% precision of K2. Combining our variability classifications with (circum)stellar properties, we find that the bursters, stochastic sources, and the largest amplitude quasi-periodic stars have larger infrared colors, and hence stronger circumstellar disks. They also tend to have larger H{alpha} equivalent widths, indicative of higher accretion rates. The dippers, on the other hand, cluster toward moderate infrared colors and low H{alpha}. Using resolved disk observations, we further find that the latter favor high inclinations, except for a few notable exceptions with close to face-on disks. These observations support the idea that YSO time-domain properties are dependent on several factors, including accretion rate and view angle.
- ID:
- ivo://CDS.VizieR/J/other/ApSS/365.112
- Title:
- Kinematic data for high luminosity stars
- Short Name:
- J/other/ApSS/365
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- We calculated the median parallaxes for 47 OB associations including at least 10 stars with known Gaia DR2 parallaxes. A comparison between trigonometric and photometric parallaxes of OB associations reveals a zero-point offset of {Delta}_{pi}_=-0.11+/-0.04mas indicating that Gaia DR2 parallaxes are, on average, underestimated and the distances derived from them are overestimated. The correction of {Delta}_{pi}=-0.11 mas is consistent with the estimate that Arenou et al. (2018A&A...616A..17A) obtained for bright stars. An analysis of parallaxes of OB associations and high-luminosity field stars confirms our previous conclusion (Dambis et al., 2001AstL...27...58D) that the distance scale for OB stars established by Blaha and Humphreys (1989AJ.....98.1598B) must be reduced by 10-20%. Spurious systematic motions of 10-20km/s at the distances of 2-3kpc from the Sun are found to arise from the use of the uncorrected Gaia DR2 parallaxes.
