- ID:
- ivo://CDS.VizieR/J/AJ/124/1001
- Title:
- JHKs photometry of Cha I variables
- Short Name:
- J/AJ/124/1001
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a J, H, and Ks photometric monitoring campaign of a 0.72{deg}x6{deg} area centered on the Chamaeleon I star-forming region. Data were obtained on 15 separate nights over a 4 month time interval, from January to May 2000, using the Two Micron All Sky Survey south telescope. Out of a total of 34,539 sources brighter than the photometric completeness limits (J=16.0, H=15.2, and Ks=14.8), 95 exhibit near-infrared variability in one or more bands. The variables can be grouped into a population of bright, red objects that are associated with the Chamaeleon I association and a population of faint, blue variables that are dispersed over the full 6{deg} of the survey and are likely field stars or older pre-main-sequence stars unrelated to the present-day Chamaeleon I molecular cloud. Ten new candidate members of Chamaeleon I, including eight brown dwarf candidates, have been identified based on variability and/or near-infrared-excess emission in the J-H versus H-Ks color-color diagram. We also provide a compendium of astrometry and J, H, and Ks photometry for previously identified members and candidate members of Chamaeleon I.
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Search Results
- ID:
- ivo://CDS.VizieR/J/other/BASI/35.53
- Title:
- JH photometry of Berkeley 59
- Short Name:
- J/other/BASI/35.
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present near-infrared JH photometry and optical slitless spectroscopy of stars in the field of the young cluster Be 59. The J/(J-H) colour-magnitude diagram of the cluster yields a distance modulus of (m-M)_0_=10.0+/-0.2mag, which corresponds to a distance of 1.0+/-0.1kpc. Using the slitless spectroscopy we identified 9 H{alpha} emission line stars in the observed region. The location of H{alpha} stars in the CMD indicates that they may be pre-main sequence stars. We have estimated the age of the cluster using the turn-off and turn-on points and is found to lie between ~1Myr to 4Myr. Two massive stars (~25M_{sun}_) in the cluster region have high membership probability which indicates that the low mass stars (~0.8M_{sun}_) may co-exist with massive stars.
- ID:
- ivo://CDS.VizieR/J/A+A/420/173
- Title:
- JK photometry of Omega Cen red giants
- Short Name:
- J/A+A/420/173
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The IR catalogue of omega Cen is based on ground-based observations using SOFI (Infrared Spectrograph and Imaging Camera on the NTT telescope at ESO, La Silla) and contains about 73000 stars covering an area of 13"x13" around the center of the cluster. The limiting magnitude is K<=17.5m and the positional accuracy is better than 0.2"
- ID:
- ivo://CDS.VizieR/J/A+A/409/147
- Title:
- J magnitude of IC 348 brown dwarfs
- Short Name:
- J/A+A/409/147
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We use a deep near-infrared census of the young stellar cluster IC 348 to construct and analyze its luminosity function. Our mosaic image of IC 348 covers the full extent of the cluster with a completeness limit of J~19.5 and is therefore sensitive for 2Myr old cluster members with masses as low as M>=0.005M_{sun}_ or the mean extinction of the known cluster members (A_V_~3.5mag).
- ID:
- ivo://CDS.VizieR/J/ApJ/540/1016
- Title:
- K-band & NICMOS photometry of Trapezium Cluster
- Short Name:
- J/ApJ/540/1016
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have obtained images of the Trapezium Cluster (140"x140"; 0.3pc x 0.3pc) with the Hubble Space Telescope Near-Infrared Camera and Multi-Object Spectrometer (NICMOS). Combining these data with new ground-based K-band spectra (R=800) and existing spectral types and photometry, we have constructed an H-R diagram and used it and other arguments to infer masses and ages.
- ID:
- ivo://CDS.VizieR/J/A+A/494/1137
- Title:
- K-band spectral catalog of Quintuplet cluster
- Short Name:
- J/A+A/494/1137
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Three very massive clusters are known to reside in the Galactic center region, the Arches cluster, the Quintuplet cluster, and the central parsec cluster, each of them rich in young hot stars. With new infrared instruments, this region is no longer obscured for the observer. For understanding these very massive clusters, it is essential to know their stellar inventory. We provide comprehensive spectroscopic data for the stellar population of the Quintuplet cluster that will form the basis of subsequent spectral analyses. Spectroscopic observations of the Quintuplet cluster were obtained with the Integral Field Spectrograph SINFONI-SPIFFI at the ESO-VLT, with the ESO VLT UT4 (Yepun) telescope between May and July 2006. The inner part of the Quintuplet cluster covered by 22 slightly overlapping fields, each of them of 8"x8" in size. The spectral range comprises the near-IR K-band from 1.94 to 2.45um. The 3D data cubes of the individual fields were flux-calibrated and combined to one contiguous cube, from which the spectra of all detectable point sources were extracted.
- ID:
- ivo://CDS.VizieR/J/A+A/568/L13
- Title:
- K-band spectrum of the very massive star W49nr1
- Short Name:
- J/A+A/568/L13
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Very massive stars (M>100M_{sun}_) are very rare objects, but have a strong influence on their environment. The formation of this kind of objects is of prime importance in star formation, but observationally still poorly constrained. We report on the identification of a very massive star in the central cluster of the star-forming region W49. We investigate near-infrared K-band spectroscopic observations of W49 from VLT/ISAAC together with JHK images obtained with NTT/SOFI and LBT/LUCI. We derive a spectral type of W49nr1, the brightest star in the dense core of the central cluster of W49.
- ID:
- ivo://CDS.VizieR/J/ApJ/751/132
- Title:
- Keck observations of the Arches cluster
- Short Name:
- J/ApJ/751/132
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the first detection of the intrinsic velocity dispersion of the Arches cluster - a young (~2Myr), massive (10^4^M_{sun}_) starburst cluster located only 26pc in projection from the Galactic center. This was accomplished using proper motion measurements within the central 10"x10" of the cluster, obtained with the laser guide star adaptive optics system at Keck Observatory over a three-year time baseline (2006-2009). This uniform data set results in proper motion measurements that are improved by a factor ~5 over previous measurements from heterogeneous instruments. By careful, simultaneous accounting of the cluster and field contaminant distributions as well as the possible sources of measurement uncertainties, we estimate the internal velocity dispersion to be 0.15+/-0.01mas/yr, which corresponds to 5.4+/-0.4km/s at a distance of 8.4kpc. Collateral benefits of our data and analysis include: (1) cluster membership probabilities, which may be used to extract a clean-cluster sample for future photometric work; (2) a refined estimate of the bulk motion of the Arches cluster with respect to the field, which we find to be 172+/-15km/s, which is slightly slower than suggested by previous measurements using one epoch each with the Very Large Telescope and the Keck telescope; and (3) a velocity dispersion estimate for the field itself, which is likely dominated by the inner Galactic bulge and the nuclear disk.
- ID:
- ivo://CDS.VizieR/J/MNRAS/469/4718
- Title:
- Kepler red-clump stars in NGC6819 and NGC6791
- Short Name:
- J/MNRAS/469/4718
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Convective mixing in helium-core-burning (HeCB) stars is one of the outstanding issues in stellar modelling. The precise asteroseismic measurements of gravity-mode period spacing ({Delta}{Pi}_1_) have opened the door to detailed studies of the near-core structure of such stars, which had not been possible before. Here, we provide stringent tests of various core-mixing scenarios against the largely unbiased population of red-clump stars belonging to the old-open clusters monitored by Kepler, and by coupling the updated precise inference on {Delta}{Pi}_1_ in thousands of field stars with spectroscopic constraints. We find that models with moderate overshooting successfully reproduce the range observed of {Delta}{Pi}_1_ in clusters. In particular, we show that there is no evidence for the need to extend the size of the adiabatically stratified core, at least at the beginning of the HeCB phase. This conclusion is based primarily on ensemble studies of {Delta}{Pi}_1_ as a function of mass and metallicity. While {Delta}{Pi}_1_ shows no appreciable dependence on the mass, we have found a clear dependence of {Delta}{Pi}_1_ on metallicity, which is also supported by predictions from models.
- ID:
- ivo://CDS.VizieR/J/MNRAS/429/1466
- Title:
- Kepler stars in the NGC 6866 field
- Short Name:
- J/MNRAS/429/1466
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an analysis of stars in the field of the open cluster NGC 6866 (age 650Myr) using data from the Kepler Input Catalogue (KIC) and time series photometry from the Kepler data base. We identify 31 {delta} Scuti and 8 {gamma} Doradus pulsating variables as well as 23 red giants with solar-like oscillations. There are 4 eclipsing binaries and 106 stars showing rotational modulation indicative of starspots. We attempted to identify cluster members using their proper motions but found very poor discrimination between members and non-members. The KIC shows a concentration of stars with distance modulus V_0_-M_V_=10.47+/-0.02. We used assumed radial modes in 9 {delta} Sct stars to determine their asteroseismic luminosities and found that the distance modulus falls within three narrow ranges depending on the assignment of overtone number. One of these ranges coincides with the KIC distance modulus. The rotation periods of main-sequence stars are correlated with colour, so that a period-age-mass relation can be derived from open clusters and applied to stars of unknown ages. Surprisingly, we find that the correlation applies not only to cool stars, but extends to A-type stars in the cluster. Finally, we present measurements of solar-like oscillations in red giants, a few of which might be cluster members.
