- 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.
Number of results to display per page
Search Results
- 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.
- ID:
- ivo://CDS.VizieR/J/AJ/162/146
- Title:
- Kinematic and photometry of King 11 with Gaia EDR3
- Short Name:
- J/AJ/162/146
- Date:
- 21 Mar 2022 00:29:39
- Publisher:
- CDS
- Description:
- This paper presents an investigation of an old age open cluster King11 using Gaia's Early Data Release 3 data. Considering the stars with membership probability (P{mu})>90%, we identified 676 most probable cluster members within the cluster's limiting radius. The mean proper motion for King11 is determined as: {mu}x=-3.391{+/-}0.006 and {mu}y=-0.660{+/-}0.004mas/yr. The blue straggler stars of King11 show a centrally concentrated radial distribution. The values of limiting radius, age, and distance are determined as 18.51, 3.63{+/-}0.42Gyr, and 3.33{+/-}0.15kpc, respectively. The cluster's apex coordinates (A=267.84{+/-}1.01, D=-27.48{+/-}1.03) are determined using the apex diagram method and verified using the ({mu}U, {mu}T) diagram. We also obtained the orbit that the cluster follows in the Galaxy and estimated its tentative birthplace in the disk. The resulting spatial velocity of King 11 is 60.2{+/-}2.16km/s. A significant oscillation along the Z coordinate up to 0.556{+/-}0.022kpc is determined.
- ID:
- ivo://CDS.VizieR/J/AJ/125/1397
- Title:
- Kinematics, age and abundances of open clusters
- Short Name:
- J/AJ/125/1397
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have compiled two new open cluster catalogs. In the first one, there are 119 objects with ages, distances, and metallicities available, while in the second one, 144 objects have both absolute proper motion and radial velocity data, of which 45 clusters also have metallicity data available.
- ID:
- ivo://CDS.VizieR/J/ApJ/870/32
- Title:
- Kinematics in young star clusters & associations
- Short Name:
- J/ApJ/870/32
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Gaia mission has opened a new window into the internal kinematics of young star clusters at the sub-km/s level, with implications for our understanding of how star clusters form and evolve. We use a sample of 28 clusters and associations with ages from ~1-5Myr, where lists of members are available from previous X-ray, optical, and infrared studies. Proper motions from Gaia DR2 reveal that at least 75% of these systems are expanding; however, rotation is only detected in one system. Typical expansion velocities are on the order of ~0.5km/s, and in several systems, there is a positive radial gradient in expansion velocity. Systems that are still embedded in molecular clouds are less likely to be expanding than those that are partially or fully revealed. One-dimensional velocity dispersions, which range from {sigma}_1D_=1 to 3km/s, imply that most of the stellar systems in our sample are supervirial and that some are unbound. In star-forming regions that contain multiple clusters or subclusters, we find no evidence that these groups are coalescing, implying that hierarchical cluster assembly, if it occurs, must happen rapidly during the embedded stage.
- ID:
- ivo://CDS.VizieR/J/PAZh/32/906
- Title:
- Kinematics of Gould Belt Based on Open Clusters
- Short Name:
- J/PAZh/32/906
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have redetermined kinematic parameters of the Gould Belt using currently available data on the motion of nearby young (logt<7.91) open clusters, OB associations, and moving stellar groups. Our modeling shows that the residual velocities reach their maximum values of -4km/s for rotation (in the direction of Galactic rotation) and +4km/s for expansion at a distance from the kinematic center of 300pc. We have taken the following parameters of the Gould Belt center: R_0_=150pc and l_0_=128{deg}. The whole structure is shown to move relative to the local standard of rest at a velocity of 10.7+/-0.7km/s in the direction l=274+/-4{deg} and b=-1+/-3{deg}. Using the derived rotation velocity, we have estimated the virial mass of the Gould Belt to be 1.5 million solar masses.
- ID:
- ivo://CDS.VizieR/J/ApJ/697/1103
- Title:
- Kinematics of Orion Nebula Cluster
- Short Name:
- J/ApJ/697/1103
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a kinematic study of the Orion Nebula Cluster (ONC) based upon RVs measured by multifiber echelle spectroscopy at the 6.5m MMT and Magellan telescopes. Velocities are reported for 1613 stars, with multi-epoch data for 727 objects as part of our continuing effort to detect and analyze spectroscopic binaries (SBs). We confirm and extend the results of Furesz et al. (2008, Cat. J/ApJ/676/1109), showing that the ONC is not relaxed, consistent with its youth, and that the stars generally follow the position-velocity structure of the moderate density gas in the region, traced by ^13^CO. The additional RVs we have measured enable us to probe some discrepancies between stellar and gaseous structure which can be attributed to binary motion and the inclusion of nonmembers in our kinematic sample. Our multi-epoch data allow us to identify 89 SBs; more will be found as we continue monitoring. Our results reinforce the idea that the ONC is a cluster in formation, and thus provide a valuable testing ground for theory.
- ID:
- ivo://CDS.VizieR/J/A+A/563/A94
- Title:
- Kinematics of the Gamma Vel cluster
- Short Name:
- J/A+A/563/A94
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A key science goal of the Gaia-ESO survey (GES) at the VLT is to use the kinematics of low-mass stars in young clusters and star forming regions to probe their dynamical histories and how they populate the field as they become unbound. The clustering of low-mass stars around the massive Wolf-Rayet binary system {gamma}^2^ Velorum was one of the first GES targets. Targets were selected from colour-magnitude diagrams and intermediate resolution spectroscopy was used to derive radial velocities and assess membership from the strength of the LiI 6708{AA} line. The radial velocity distribution was analysed using a maximum likelihood technique that accounts for unresolved binaries.
- ID:
- ivo://CDS.VizieR/J/MNRAS/407/2109
- Title:
- Kinematic study of open clusters
- Short Name:
- J/MNRAS/407/2109
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Galactic population of open clusters provides an insight into star formation in the Galaxy. The open cluster catalogue by Dias et al. (Cat. B/ocl) is a rich source of data, including kinematic information. This large sample made it possible to carry out a systematic analysis of 481 open cluster orbits, using parameters based on orbit eccentricity and separation from the Galactic plane. These two parameters may be indicative of origin, and we find them to be correlated. We also find them to be correlated with metallicity, another parameter suggested elsewhere to be a marker for origin in that high values of any of these two parameters generally indicate a low metallicity ([Fe/H]solar<-0.2dex). The resulting analysis points to four open clusters in the catalogue being of extragalactic origin by impact of high-velocity cloud on the disc: Berkeley 21, 32, 99 and Melotte 66, with a possible further four due to this origin (NGC 2158, 2420, 7789 and IC 1311). A further three may be due to Galactic globular cluster impact on the disc, i.e. of internal Galactic origin (NGC 6791, 1817 and 7044).
