- ID:
- ivo://CDS.VizieR/J/MNRAS/409/1281
- Title:
- Old star clusters in the FSR catalogue
- Short Name:
- J/MNRAS/409/1281
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate the old star clusters in the sample of cluster candidates from the Froebrich, Scholz & Raftery (FSR, 2007, Cat. J/MNRAS/374/399) list. Based on photometry from the Two-Micron All-Sky Survey, we generated decontaminated colour-magnitude and colour-colour diagrams to select a sample of 269 old stellar clusters. This sample contains 63 known globular clusters, 174 known open clusters and 32 so far unclassified objects. Isochrone fitting has been used to homogeneously calculate the age, distance and reddening to all clusters.
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- ID:
- ivo://CDS.VizieR/J/ApJS/151/313
- Title:
- Optical spectra in star-forming regions
- Short Name:
- J/ApJS/151/313
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present high-resolution optical spectra (at ~0.6-1.8km/s) of interstellar CN, CH, CH+, CaI, KI, and CaII absorption toward 29 lines of sight in three star-forming regions, {rho} Oph, Cep OB2, and Cep OB3. The observations and data reduction are described. The agreement between earlier measurements of the total equivalent widths and our results is quite good. However, our higher resolution spectra reveal complex structure and closely blended components in most lines of sight. The velocity component structure of each species is obtained by analyzing the spectra of the six species for a given sight line together. The tabulated column densities and Doppler parameters of individual components are determined by using the method of profile fitting. Total column densities along lines of sight are computed by summing results from profile fitting for individual components and are compared with column densities from the apparent optical depth method. A more detailed analysis of these data and their implications will be presented in a companion paper.
- ID:
- ivo://CDS.VizieR/J/ApJ/671/1784
- Title:
- Ori OB1 IRAC/MIPS observations
- Short Name:
- J/ApJ/671/1784
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new Spitzer observations of two fields in the Orion OB1 association. We report IRAC/MIPS observations for 115 confirmed members and 41 photometric candidates of the ~10Myr 25 Orionis aggregate in the OB1a subassociation, and 106 confirmed members and 65 photometric candidates of the 5Myr region located in the OB1b subassociation.
- ID:
- ivo://CDS.VizieR/J/MNRAS/468/931
- Title:
- Orion Nebula Cluster members VRI photometry
- Short Name:
- J/MNRAS/468/931
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Very young stars, like the Orion Nebula Cluster (ONC) members analysed in the present study, exhibit photometric variability with a wide range of amplitudes. Such a prominent variability reflects in the inferred values of stellar colours and luminosities and, in turn, in the inferred stellar ages and masses. In this study, we measure the amplitudes of the photometric variability in V, R and I optical bands of a sample of 346 ONC members. We use these measurements to investigate how this variability affects the inferred masses and ages and whether it alone can account for the age spread among ONC members reported by earlier studies. We make use of colour-magnitude and Hertzprung-Russell (HR) diagrams. We find that members that show periodic and smooth photometric rotational modulation have masses and ages that are unaffected by variability when theoretical isochrones and evolutionary mass tracks are used in either colour-magnitude or HR diagrams. On the other hand, members with periodic but very scattered photometric rotational modulation and non-periodic members have masses and ages that are significantly affected. Moreover, using HR diagrams, we find that the observed I-band photometric variability can take account of only a fraction (~50 per cent) of the inferred age spread, whereas the V-band photometric variability is large enough to mask any age spread.
- ID:
- ivo://CDS.VizieR/J/A+A/289/101
- Title:
- Orion OB1 association. I.
- Short Name:
- J/A+A/289/101
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- (no description available)
- ID:
- ivo://CDS.VizieR/J/A+A/508/1313
- Title:
- Orion pre-main sequence RIJH light curves
- Short Name:
- J/A+A/508/1313
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We performed an intensive photometric monitoring of the PMS stars falling in a field of about 10x10 arcminutes in the vicinity of the Orion Nebula Cluster (ONC). Photometric data were collected between November 2006 and January 2007 with the REM telescope in the VRIJHK' bands. The largest number of observations is in the I band (about 2700 images) and in J and H bands (about 500 images in each filter). From the observed rotational modulation, induced by the presence of surface inhomogeneities, we derived the rotation periods for 16 stars and improved previous determinations for the other 13. The analysis of the spectral energy distributions and, for some stars, of high-resolution spectra provided us with the main stellar parameters (luminosity, effective temperature, mass, age, and vsini). We also report the serendipitous detection of two strong flares in two of these objects. In most cases, the light-curve amplitudes decrease progressively from the R to H band as expected for cool starspots, while in a few cases, they can only be modelled by the presence of hot spots, presumably ascribable to magnetospheric accretion. The application of our own spot model to the simultaneous light curves in different bands allowed us to deduce the spot parameters and particularly to disentangle the spot temperature and size effects on the observed light curves.
- ID:
- ivo://CDS.VizieR/J/ApJ/783/130
- Title:
- Parallaxes of high mass star forming regions
- Short Name:
- J/ApJ/783/130
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Over 100 trigonometric parallaxes and proper motions for masers associated with young, high-mass stars have been measured with the Bar and Spiral Structure Legacy Survey, a Very Long Baseline Array key science project, the European VLBI Network, and the Japanese VLBI Exploration of Radio Astrometry project. These measurements provide strong evidence for the existence of spiral arms in the Milky Way, accurately locating many arm segments and yielding spiral pitch angles ranging from about 7{deg} to 20{deg}. The widths of spiral arms increase with distance from the Galactic center. Fitting axially symmetric models of the Milky Way with the three-dimensional position and velocity information and conservative priors for the solar and average source peculiar motions, we estimate the distance to the Galactic center, R_0_, to be 8.34+/-0.16kpc, a circular rotation speed at the Sun, {Theta}_0_, to be 240+/-8km/s, and a rotation curve that is nearly flat (i.e., a slope of -0.2+/-0.4km/s/kpc) between Galactocentric radii of {approx}5 and 16kpc. Assuming a "universal" spiral galaxy form for the rotation curve, we estimate the thin disk scale length to be 2.44+/-0.16kpc. With this large data set, the parameters R_0_ and {Theta}_0_are no longer highly correlated and are relatively insensitive to different forms of the rotation curve. If one adopts a theoretically motivated prior that high-mass star forming regions are in nearly circular Galactic orbits, we estimate a global solar motion component in the direction of Galactic rotation, V_{sun}_=14.6+/-5.0km/s. While {Theta}_0_and V_{sun}_are significantly correlated, the sum of these parameters is well constrained, {Theta}_0_+V_{sun}_=255.2+/-5.1km/s, as is the angular speed of the Sun in its orbit about the Galactic center, ({Theta}_0_+V_{sun}_)/R_0_=30.57+/-0.43km/s/kpc. These parameters improve the accuracy of estimates of the accelerations of the Sun and the Hulse-Taylor binary pulsar in their Galactic orbits, significantly reducing the uncertainty in tests of gravitational radiation predicted by general relativity.
- ID:
- ivo://CDS.VizieR/J/AJ/152/198
- Title:
- Periods of 4-10 Myr old T Tauri members of Orion OB1
- Short Name:
- J/AJ/152/198
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Most existing studies of the angular momentum evolution of young stellar populations have focused on the youngest (<~1-3Myr) T Tauri stars. In contrast, the angular momentum distributions of older T Tauri stars (~4-10Myr) have been less studied, even though they hold key insights to understanding stellar angular momentum evolution at a time when protoplanetary disks have largely dissipated and when models therefore predict changes in the rotational evolution that can in principle be tested. We present a study of photometric variability among 1974 confirmed T Tauri members of various subregions of the Orion OB1 association, and with ages spanning 4-10Myr, using optical time series from three different surveys. For 564 of the stars (~32% of the weak-lined T Tauri stars and ~13% of the classical T Tauri stars in our sample) we detect statistically significant periodic variations, which we attribute to the stellar rotation periods, making this one of the largest samples of T Tauri star rotation periods yet published. We observe a clear change in the overall rotation period distributions over the age range 4-10Myr, with the progressively older subpopulations exhibiting systematically faster rotation. This result is consistent with angular momentum evolution model predictions of an important qualitative change in the stellar rotation periods starting at ~5Myr, an age range for which very few observational constraints were previously available.
- ID:
- ivo://CDS.VizieR/J/MNRAS/495/3087
- Title:
- Photometric sample of 2.6million red clump stars
- Short Name:
- J/MNRAS/495/3087
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Large pristine samples of red clump stars are highly sought after given that they are standard candles and give precise distances even at large distances. However, it is difficult to cleanly select red clumps stars because they can have the same Teff and logg as red giant branch stars. Recently, it was shown that the asteroseismic parameters, {DELTA}P and {DELTA}{nu}, which are used to accurately select red clump stars, can be derived from spectra using the change in the surface carbon to nitrogen ratio ([C/N]) caused by mixing during the red giant branch. This change in [C/N] can also impact the spectral energy distribution. In this study, we predict the {DELTA}P, {DELTA}{nu}, Teff and logg using 2MASS, AllWISE, Gaia, and Pan-STARRS data in order to select a clean sample of red clump stars. We achieve a contamination rate of ~20%, equivalent to what is achieved when selecting from Teff and logg derived from low resolution spectra. Finally, we present two red clump samples. One sample has a contamination rate of ~20% and ~405000 red clump stars. The other has a contamination of ~33% and ~2.6 million red clump stars which includes ~75000 stars at distances >10kpc. For |b|>30 degrees we find ~15000 stars with contamination rate of ~9%. The scientific potential of this catalog for studying the structure and formation history of the Galaxy is vast given that it includes millions of precise distances to stars in the inner bulge and distant halo where astrometric distances are imprecise.
- ID:
- ivo://CDS.VizieR/J/AcA/58/23
- Title:
- Photometric survey for M33 stellar clusters
- Short Name:
- J/AcA/58/23
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalog of 4780 extended sources from the outer field of M33. The catalog includes 73 previously identified clusters or planetary nebulae, 1153 likely background galaxies, and 3554 new candidate stellar clusters. The survey is based on deep ground-based images obtained with the MegaCam instrument on the CFHT telescope. We provide g'r'i' photometry for detected objects as well as estimates of the FWHM and ellipticity of their profiles. The sample includes 122 new, relatively bright, likely globular clusters. Follow-up observations of fainter candidates from our list may extend the faint-end of the observed luminosity function of globular clusters in M33 by up to 3 magnitudes. The catalog includes several cluster candidates located in the outskirts of the galaxy. These objects are promising targets for deep photometry with the HST. We present a color-magnitude diagram for one detected object, showing that it is an extended and low-surface-brightness old cluster located at an angular distance of 27' from the center of M33.
