- ID:
- ivo://CDS.VizieR/J/MNRAS/424/3178
- Title:
- Pre-main-sequence isochrones. Pleiades benchmark
- Short Name:
- J/MNRAS/424/3178
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a critical assessment of commonly used pre-main-sequence isochrones by comparing their predictions to a set of well-calibrated colour-magnitude diagrams of the Pleiades in the wavelength range 0.4-2.5um. Our analysis shows that for temperatures less than 4000K, the models systematically overestimate the flux by a factor of 2 at 0.5um, though this decreases with wavelength, becoming negligible at 2.2um. In optical colours this will result in the ages for stars younger than 10Myr being underestimated by factors of between 2 and 3. We show that using observations of standard stars to transform the data into a standard system can introduce significant errors in the positioning of pre-main sequences in colour-magnitude diagrams. Therefore, we have compared the models to the data in the natural photometric system in which the observations were taken. Thus we have constructed and tested a model of the system responses for the Wide-Field Camera on the Isaac Newton Telescope. As a benchmark test for the development of pre-main-sequence models, we provide both our system responses and the Pleiades sequence.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/658/480
- Title:
- Pre-main-sequence stars in Lupus association
- Short Name:
- J/ApJ/658/480
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Kinematical analysis of spectroscopically identified pre-main-sequence stars associated with the Lupus dark cloud reveals a streamlike motion of low internal velocity dispersion (<=1.3km/s). A statistically significant mismatch between the convergent point radial velocity and the spectroscopic radial velocity from the literature indicates a moderate degree of expansion. The rate of expansion is too low to account for the present extent of the association if one assumes that the spatially dispersed population was formed in the dense molecular cores observed today. Therefore, it is unlikely that the outlying weak-lined T Tauri members were born in the same star-forming cores as the more compactly located classical T Tauri stars, despite the kinematic integrity of the association. Distances inferred from the classical moving-cluster method show a large depth of the association (~80pc) along the line of sight. A color-magnitude diagram of the association in the near-IR colors corrected for the distribution of distances shows a clear gap separating the older (5-27Myr) and the younger (~1Myr) generations of stars. Half of the identified 1Myr old stars lie in the tight group of mostly classical T Tauri stars associated with the Lupus 3 dark filament. This nest of very young stars appears to be 25pc farther from the Sun than the center of the greater Lupus association.
- ID:
- ivo://CDS.VizieR/J/A+A/438/769
- Title:
- Pre-main sequence stars Proper Motion Catalog
- Short Name:
- J/A+A/438/769
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This catalogue presents astrometric (position and proper motion) and photometric parameters for 1250 PMS stars and 104 PMS star candidates spread over all-sky major star-forming regions. We provide for each star the mean (J2000.0) position and proper motion derived from CCD meridian observations(Bordeaux and Valinhos CCD meridian circle), ESOD1.5m and OHP120cm telescopes, Schmidt SERC-J, POSS I and POSS II plates digitized with the MAMA measuring machine (Paris) and published catalogues as AC2000.2 (<I/275>), USNO-A2.0 (<I/252>), HIPPARCOS (<I/239>), Tycho-2 (<I/259>), UCAC2 (<I/289>), 2MASS (<II/246>) and other astrometric sources. We also provide, when available, CCD meridian V magnitude and the J, H, K magnitudes from 2MASS catalogue. Precision on proper motions vary from 2 to 5mas/yr depending on the used sources of ancient positions and depending also on the embedding and binarity of the source. The V limiting magnitude of our catalogue is about 16.5.
- ID:
- ivo://CDS.VizieR/J/ApJ/696/L84
- Title:
- Primordial circumstellar disks in binary systems
- Short Name:
- J/ApJ/696/L84
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We combine the results from several multiplicity surveys of pre-main-sequence stars located in four nearby star-forming regions with Spitzer data from three different Legacy Projects. This allows us to construct a sample of 349 targets, including 125 binaries, which we use to to investigate the effect of companions on the evolution of circumstellar disks. We find that the distribution of projected separations of systems with Spitzer excesses is significantly different (P~2.4e-5, according to the K-S test for binaries with separations less than 400AU) from that of systems lacking evidence for a disk. As expected, systems with projected separations less than 40AU are half as likely to retain at least one disk than are systems with projected separations in the 40-400AU range. These results represent the first statistically significant evidence for a correlation between binary separation and the presence of an inner disk (r~1AU). Several factors (e.g., the incompleteness of the census of close binaries, the use of unresolved disk indicators, and projection effects) have previously masked this correlation in smaller samples. We discuss the implications of our findings for circumstellar disk lifetimes and the formation of planets in multiple systems.
- ID:
- ivo://CDS.VizieR/J/ApJS/209/32
- Title:
- Probable young stars in the MYStIX project
- Short Name:
- J/ApJS/209/32
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Massive Young star-forming complex Study in Infrared and X-rays (MYStIX) project requires samples of young stars that are likely members of 20 nearby Galactic massive star-forming regions. Membership is inferred from statistical classification of X-ray sources, from detection of a robust infrared excess that is best explained by circumstellar dust in a disk or infalling envelope and from published spectral types that are unlikely to be found among field stars. We present the MYStIX membership lists here, and describe in detail the statistical classification of X-ray sources via a "Naive Bayes Classifier."
- ID:
- ivo://CDS.VizieR/J/A+A/616/A157
- Title:
- Probing star formation and ISM properties. II
- Short Name:
- J/A+A/616/A157
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We evaluate dust-corrected far-ultraviolet (FUV) star formation rates (SFRs) for samples of star-forming galaxies at z~0 and z~0.7 and find significant differences between values obtained through corrections based on UV colour, from a hybrid mid-infrared (MIR) plus FUV relation, and from a radiative transfer based attenuation correction method. The performances of the attenuation correction methods are assessed by their ability to remove the dependency of the corrected SFR on inclination, as well as returning, on average, the expected population mean SFR. We find that combining MIR (rest-frame ~13um) and FUV luminosities gives the most inclination-independent SFRs and reduces the intrinsic SFR scatter of the methods we tested. However, applying the radiative transfer based method gives corrections to the FUV SFR that are inclination independent and in agreement with the expected SFRs at both z~0 and z~0.7. SFR corrections based on the UV-slope perform worse than the other two methods we tested. For our local sample, the UV-slope method works on average, but does not remove inclination biases. At z~0.7, we find that the UV-slope correction we used locally flattens the inclination dependence compared to the raw FUV measurements, but was not sufficient to correct for the large attenuation observed at z~0.7.
- ID:
- ivo://CDS.VizieR/J/ApJ/800/120
- Title:
- Profiles of z<0.5 galaxies with Pan-STARRS1
- Short Name:
- J/ApJ/800/120
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of an analysis of Pan-STARRS1 Medium Deep Survey multi-band (grizy) images of a sample of 698 low-redshift disk galaxies that span broad ranges in stellar mass, star-formation rate, and bulge/disk ratio. We use population synthesis spectral energy distribution fitting techniques to explore the radial distribution of the light, color, surface mass density, mass/light ratio, and age of the stellar populations. We characterize the structure and stellar content of the galaxy disks out to radii of about twice Petrosian r_90_, beyond which the halo light becomes significant. We measure normalized radial profiles for sub-samples of galaxies in three bins each of stellar mass and concentration. We also fit radial profiles to each galaxy. The majority of galaxies have down-bending radial surface brightness profiles in the bluer bands with a break radius at roughly r_90_. However, they typically show single unbroken exponentials in the reddest bands and in the stellar surface mass density. We find that the mass/light ratio and stellar age radial profiles have a characteristic "U" shape. There is a good correlation between the amplitude of the down-bend in the surface brightness profile and the rate of the increase in the M/L ratio in the outer disk. As we move from late- to early-type galaxies, the amplitude of the down-bend and the radial gradient in M/L both decrease. Our results imply a combination of stellar radial migration and suppression of recent star formation can account for the stellar populations of the outer disk.
- ID:
- ivo://CDS.VizieR/J/ApJ/807/170
- Title:
- Prograde vs retrogade motions. II. KOIs
- Short Name:
- J/ApJ/807/170
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Mazeh et al. (Paper I: 2015ApJ...800..142M) have presented an approach that can, in principle, use the derived transit timing variation (TTV) of some transiting planets observed by the Kepler mission to distinguish between the prograde and retrograde motion of their orbits with respect to their parent stars' rotation. The approach utilizes TTVs induced by spot-crossing events that occur when the planet moves across a spot on the stellar surface, looking for a correlation between the derived TTVs and the stellar brightness derivatives at the corresponding transits. This can work even in data that cannot temporally resolve the spot-crossing events themselves. Here, we apply this approach to the Kepler KOIs, identifying nine systems where the photometric spot modulation is large enough and the transit timing accurate enough to allow detection of a TTV-brightness-derivatives correlation. Of those systems, five show highly significant prograde motion (Kepler-17b, Kepler-71b, KOI-883.01, KOI-895.01, and KOI-1074.01), while no system displays retrograde motion, consistent with the suggestion that planets orbiting cool stars have prograde motion. All five systems have impact parameter 0.2<~b<~0.5, and all systems within that impact parameter range show significant correlation, except HAT-P-11b where the lack of a correlation follows its large stellar obliquity. Our search suffers from an observational bias against detection of high impact parameter cases, and the detected sample is extremely small. Nevertheless, our findings may suggest that stellar spots, or at least the larger ones, tend to be located at low stellar latitude, but not along the stellar equator, similar to the Sun.
- ID:
- ivo://CDS.VizieR/J/A+A/451/901
- Title:
- Proper motion and BV photometry in Trumpler 2
- Short Name:
- J/A+A/451/901
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The results of a complex study of the galactic open cluster Trumpler 2 are presented. In order to obtain the proper motions, the positions of approximately 3000 stars up to the limit magnitude B~16.25mag in the area 80'x80' around the cluster were measured on 6 plates with a maximal epoch difference of 63-years. The root-mean error of the relative proper motions is 4.2mas/yr. The catalogue of BV magnitudes of all the stars in the investigated area was compiled. The selection of the cluster members within the region of R<16 arcmin from the center of the cluster was made. Altogether, 148 stars were considered to be cluster members by both astrometrical and photometrical criteria. We present the estimated age (8.91E+07) and physical parameters of the cluster and append the catalogues of the proper motions and of the photometry of the stars.
5280. Proper motion in M34
- ID:
- ivo://CDS.VizieR/J/AJ/111/1193
- Title:
- Proper motion in M34
- Short Name:
- J/AJ/111/1193
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have measured proper motions, positions, magnitudes, and colors for 630 stars to V~16.2 in the vicinity of the open cluster NGC 1039=M34. A proper motion membership probability analysis has been performed. We give for all stars the equatorial coordinates, the proper motions, the V magnitude, and the membership probability. For the most likely cluster members we also give B-V and (V-I)K colors. Cross identifications with previous surveys are also provided. We find an age for the cluster of 200-250Myr and a distance of 475parsecs.
