- 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).
Number of results to display per page
Search Results
- 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.
- ID:
- ivo://CDS.VizieR/J/ApJ/540/236
- Title:
- KH photometry of Orion Nebula Cluster
- Short Name:
- J/ApJ/540/236
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a 0.5"-0.9" FWHM imaging survey at K (2.2{mu}m) and H (1.6{mu}m) covering ~ 5.1'x5.1' centered on {theta}^1^C Ori, the most massive star in the Orion Nebula Cluster (ONC). At the age and distance of this cluster, and in the absence of extinction, the hydrogen-burning limit (0.08M_{sun}_) occurs at K~13.5mag, while an object of mass 0.02M_{sun}_ has K~16.2mag. Our photometry is complete for source detection at the 7{sigma} level to K~17.5mag and thus is sensitive to objects as low-mass as 0.02M_{sun}_ seen through visual extinction values as high as 10mag. We use the observed magnitudes, colors, and star counts to constrain the shape of the inner ONC stellar mass function across the hydrogen-burning limit. After determining the stellar age and near-infrared excess properties of the optically visible stars in this same inner ONC region, we present a new technique that incorporates these distributions when extracting the mass function from the observed density of stars in the K-(H-K) diagram. We find that our data are inconsistent with a mass function that rises across the stellar/substellar boundary. Instead, we find that the most likely form of the inner ONC mass function is one that rises to a peak around 0.15M_{sun}_, and then declines across the hydrogen-burning limit with slope N(log M){prop.to}M^0.57^. We emphasize that our conclusions apply to the inner 0.71pc x 0.71pc of the ONC only; they may not apply to the ONC as a whole where some evidence for general mass segregation has been found.
- ID:
- ivo://CDS.VizieR/J/ApJ/831/11
- Title:
- KIC 9777062 RVs & asteroseismology in NGC6811
- Short Name:
- J/ApJ/831/11
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the analysis of an eccentric, partially eclipsing long-period (P=19.23 days) binary system KIC 9777062 that contains main-sequence stars near the turnoff of the intermediate-age open cluster NGC 6811. The primary is a metal-lined Am star with a possible convective blueshift to its radial velocities, and one star (probably the secondary) is likely to be a {gamma} Dor pulsator. The component masses are 1.603+/-0.006(stat.)+/-0.016(sys.) and 1.419+/-0.003+/-0.008M_{sun}_, and the radii are 1.744+/-0.004+/-0.002 and 1.544+/-0.002+/-0.002R_{sun}_. The isochrone ages of the stars are mildly inconsistent: the age from the mass-radius combination for the primary (1.05+/-0.05+/-0.09Gyr, where the last quote was systematic uncertainty from models and metallicity) is smaller than that from the secondary (1.21+/-0.05+/-0.15Gyr) and is consistent with the inference from the color-magnitude diagram (1.00+/-0.05Gyr). We have improved the measurements of the asteroseismic parameters {Delta}{nu} and {nu}_max_ for helium-burning stars in the cluster. The masses of the stars appear to be larger (or alternately, the radii appear to be smaller) than predicted from isochrones using the ages derived from the eclipsing stars. The majority of stars near the cluster turnoff are pulsating stars: we identify a sample of 28 {delta} Sct, 15 {gamma} Dor, and 5 hybrid types. We used the period-luminosity relation for high-amplitude {delta} Sct stars to fit the ensemble of the strongest frequencies for the cluster members, finding (m-M)_V_=10.37+/-0.03. This is larger than most previous determinations, but smaller than values derived from the eclipsing binary (10.47+/-0.05).
- ID:
- ivo://CDS.VizieR/J/ApJ/729/L10
- Title:
- KIC stars properties in NGC 6791 and NGC 6819
- Short Name:
- J/ApJ/729/L10
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present initial results on some of the properties of open clusters NGC 6791 and NGC 6819 derived from asteroseismic data obtained by NASA's Kepler mission. In addition to estimating the mass, radius, and log g of stars on the red giant branch (RGB) of these clusters, we estimate the distance to the clusters and their ages. Our model-independent estimate of the distance modulus of NGC 6791 is (m-M)_0_=13.11+/-0.06. We find (m-M)_0_=11.85+/-0.05 for NGC 6819. The average mass of stars on the RGB of NGC 6791 is 1.20+/-0.01M_{sun}_, while that of NGC 6819 is 1.68+/-0.03M_{sun}_. It should be noted that we do not have data that cover the entire RGB and the actual mass will be somewhat lower. We have determined model-dependent estimates of ages of these clusters. We find ages between 6.8 and 8.6Gyr for NGC 6791, however, most sets of models give ages around 7Gyr. We obtain ages between 2 and 2.4Gyr for NGC 6819.