- ID:
- ivo://CDS.VizieR/J/ApJ/794/125
- Title:
- IN-SYNC. I. APOGEE stellar parameters
- Short Name:
- J/ApJ/794/125
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Over two years, 8859 high-resolution H-band spectra of 3493 young (1-10Myr) stars were gathered by the multi-object spectrograph of the APOGEE project as part of the IN-SYNC ancillary program of the SDSS-III survey. Here we present the forward modeling approach used to derive effective temperatures, surface gravities, radial velocities, rotational velocities, and H-band veiling from these near-infrared spectra. We discuss in detail the statistical and systematic uncertainties in these stellar parameters. In addition, we present accurate extinctions by measuring the E(J-H) of these young stars with respect to the single-star photometric locus in the Pleiades. Finally, we identify an intrinsic stellar radius spread of about 25% for late-type stars in IC 348 using three (nearly) independent measures of stellar radius, namely, the extinction-corrected J-band magnitude, the surface gravity, and the Rsini from the rotational velocities and literature rotation periods. We exclude that this spread is caused by uncertainties in the stellar parameters by showing that the three estimators of stellar radius are correlated, so that brighter stars tend to have lower surface gravities and larger Rsini than fainter stars at the same effective temperature.
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- ID:
- ivo://CDS.VizieR/J/ApJ/807/27
- Title:
- IN-SYNC. III. Radial velocities of IC348 stars
- Short Name:
- J/ApJ/807/27
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Most field stars will have encountered the highest stellar density and hence the largest number of interactions in their birth environment. Yet the stellar dynamics during this crucial phase are poorly understood. Here we analyze the radial velocities measured for 152 out of 380 observed stars in the 2-6Myr old star cluster IC 348 as part of the SDSS-III APOGEE. The radial velocity distribution of these stars is fitted with one or two Gaussians, convolved with the measurement uncertainties including binary orbital motions. Including a second Gaussian improves the fit; the high-velocity outliers that are best fit by this second component may either (1) be contaminants from the nearby Perseus OB2 association, (2) be a halo of ejected or dispersing stars from IC 348, or (3) reflect that IC 348 has not relaxed to a Gaussian velocity distribution. We measure a velocity dispersion for IC 348 of 0.72+/-0.07km/s (or 0.64+/-0.08km/s if two Gaussians are fitted), which implies a supervirial state, unless the gas contributes more to the gravitational potential than expected. No evidence is found for a dependence of this velocity dispersion on distance from the cluster center or stellar mass. We also find that stars with lower extinction (in the front of the cloud) tend to be redshifted compared with stars with somewhat higher extinction (toward the back of the cloud). This data suggest that the stars in IC 348 are converging along the line of sight. We show that this correlation between radial velocity and extinction is unlikely to be spuriously caused by the small cluster rotation of 0.024+/-0.013km/s/arcmin or by correlations between the radial velocities of neighboring stars. This signature, if confirmed, will be the first detection of line of sight convergence in a star cluster. Possible scenarios for reconciling this convergence with IC 348's observed supervirial state include: (a) the cluster is fluctuating around a new virial equilibrium after a recent disruption due to gas expulsion or a merger event, or (b) the population we identify as IC 348 results from the chance alignment of two sub-clusters converging along the line of sight. Additional measurements of tangential and radial velocities in IC 348 will be important for clarifying the dynamics of this region and informing models of the formation and evolution of star clusters.
- ID:
- ivo://CDS.VizieR/J/ApJ/869/72
- Title:
- IN-SYNC. VIII. YSOs in NGC 1333, IC 348 and Orion A
- Short Name:
- J/ApJ/869/72
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this paper, we address two issues related to primordial disk evolution in three clusters (NGC1333, IC348, and OrionA) observed by the INfrared Spectra of Young Nebulous Clusters (IN-SYNC) project. First, in each cluster, averaged over the spread of age, we investigate how disk lifetime is dependent on stellar mass. The general relation in IC348 and OrionA is that primordial disks around intermediate-mass stars (2-5M_{sun}_) evolve faster than those around loss-mass stars (0.1-1M_{sun}_), which is consistent with previous results. However, considering only low-mass stars, we do not find a significant dependence of disk frequency on stellar mass. These results can help to better constrain theories on gas giant planet formation timescales. Second, in the OrionA molecular cloud, in the mass range of 0.35-0.7M_{sun}_, we provide the most robust evidence to date for disk evolution within a single cluster exhibiting modest age spread. By using surface gravity as an age indicator and employing 4.5{mu}m excess as a primordial disk diagnostic, we observe a trend of decreasing disk frequency for older stars. The detection of intra-cluster disk evolution in NGC1333 and IC348 is tentative, since the slight decrease of disk frequency for older stars is a less than 1{sigma} effect.
- ID:
- ivo://CDS.VizieR/J/A+A/504/681
- Title:
- Integrated BVJHKs for 650 open clusters
- Short Name:
- J/A+A/504/681
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We determine the integrated magnitudes and colours of 650 clusters in optical (BV) and the near-infrared (JHKs) passbands and construct the luminosity functions of the Galactic open clusters in these passbands.
- ID:
- ivo://CDS.VizieR/J/MNRAS/403/1491
- Title:
- Integrated magnitudes of synthetic star clusters
- Short Name:
- J/MNRAS/403/1491
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This paper presents integrated magnitudes and colours for synthetic clusters. The integrated parameters have been obtained for the whole cluster population as well as for the main-sequence (MS) population of star clusters. We have also estimated observed integrated magnitudes and colours of the MS population of galactic open clusters, Large Magellanic Cloud (LMC) and Small Magellanic Cloud (SMC) star clusters.
- ID:
- ivo://CDS.VizieR/J/A+AS/104/379
- Title:
- Integrated Photometry of open clusters
- Short Name:
- J/A+AS/104/379
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Galactic open clusters provide an abundant sample of stellar aggregates of various sizes, ages and metal abundances, apt to constitute a template for comparison with star systems in other galaxies. In this paper we present and discuss a standard methodology to synthesize U,B,V fluxes and colours, and apply it to a set of 138 open clusters. Results are compared with previous ones available in the literature. We were able to calibrate a mass-luminosity relation by which we evaluated the mass of ~ 400 open clusters, leading to a well defined present-day mass function. The number-complete sample of galactic open clusters presented in Battinelli & Capuzzo-Dolcetta (1992AJ....103.1596B) is enlarged of a 15%.
- ID:
- ivo://CDS.VizieR/J/MNRAS/335/233
- Title:
- Integrated Spectra of Open Clusters
- Short Name:
- J/MNRAS/335/233
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a library of 39 open cluster optical/near-IR integrated spectra. The data were obtained at CASLEO (San Juan, Argentina) and LNA (Itajuba, Brazil). Eight additional spectra obtained at ESO (La Silla, Chile), also employed in the present analysis, are already available at CDS (see cat. <III/219>). The data were combined in order to derive high S/N templates of young and intermediate-age populations sampling their evolutionary states with unprecedented time resolution at nearly solar metallicity. These template spectra, also included in the library, are useful, e.g., for population synthesis techniques applied to galaxies and for estimates of individual cluster parameters in the Milky Way as well as in external galaxies.
- ID:
- ivo://CDS.VizieR/J/ApJ/726/19
- Title:
- Intermediate-mass stars in IC 1805
- Short Name:
- J/ApJ/726/19
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the results of a study of the intermediate- and high-mass stars in the young, rich star-forming complex IC 1805, based on a combination of optical, near-infrared, and mid-infrared photometry, and classification spectra. These data provide the basis for characterizing the masses and ages for stars more massive than ~2M_{sun}_ and enable a study of the frequency and character of circumstellar disks associated with intermediate- and high-mass stars. Optically thick accretion disks among stars with masses 2<M/M_{sun}_<4 are rare (~2% of members) and absent among more massive stars. A larger fraction (~10%) of stars with masses 2<M/M_{sun}_<4 appear to be surrounded by disks that have evolved from the initial optically thick accretion phase. We identify four classes of such disks. These classes are based on spectral energy distributions (SEDs) of excess emission above photospheric levels: disks that are (1) optically thin based on the magnitude of the observed excess emission from 2 to 24um, (2) optically thin in their inner regions (r<20AU) and optically thick in their outer regions, (3) exhibit empty inner regions (r<10AU) and optically thin emission in their outer regions, and (4) exhibit empty inner regions and optically thick outer regions. We discuss, and assess the merits and liabilities of, proposed explanations for disks exhibiting these SED types and suggest additional observations that would test these proposals.
- ID:
- ivo://CDS.VizieR/J/A+A/507/833
- Title:
- Interstellar CaII lines for 290 stars
- Short Name:
- J/A+A/507/833
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We attempt to extend the relation between the strengths of the interstellar CaII lines and the distances to early-type stars to objects beyond 1 kiloparsec, with the line saturation taken into account. We measure the CaII K and CaII H equivalent widths, and compute Ca II column densities for 262 lines of sight towards early-type stars with available Hipparcos parallaxes (pi). The targets are located within a few hundred parsecs of the Galactic plane, and span all the range of Galactic longitudes. We fit the N_CaII_ - parallax relation with a function of the form pi=1/(a.N_CaII_+b), using a maximum-likelihood approach to take account of errors in both variables. We use the resultant formula to estimate distances to stars in OB associations and clusters, and compare them to those found in the literature, usually estimated by spectrophotometric methods.
- ID:
- ivo://CDS.VizieR/J/MNRAS/415/103
- Title:
- IPHAS T Tauri candidates in IC 1396
- Short Name:
- J/MNRAS/415/103
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Isaac Newton Telescope (INT) Photometric H-Alpha Survey (IPHAS) is a 1800deg^2^ survey of the Northern Galactic Plane, reaching down to r'~21. We demonstrate how the survey can be used to (1) reliably select classical T Tauri star candidates and (2) constrain the mass accretion rates with an estimated relative uncertainty of 0.6dex. IPHAS is a necessary addition to spectroscopic surveys because it allows large and uniform samples of accretion rates to be obtained with a precise handle on the selection effects. We apply the method on a region of 7deg^2^ towards the HII region IC 1396 in Cepheus OB2 and identify 158 pre-main-sequence candidates with masses between 0.2 and 2.0M_{sun}_ and accretion rates between 10-9.2 and 10-7.0M_{sun}_/yr.
