- 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.
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- ID:
- ivo://CDS.VizieR/J/A+A/605/A86
- Title:
- Pre-main sequence stars VLT/X-Shooter spectra
- Short Name:
- J/A+A/605/A86
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Studies of the formation and evolution of young stars and their disks rely on knowledge of the stellar parameters of the young stars. The derivation of these parameters is commonly based on comparison with photospheric template spectra. Furthermore, chromospheric emission in young active stars impacts the measurement of mass accretion rates, a key quantity for studying disk evolution. Here we derive stellar properties of low-mass (M*~<2M_{sun}_) pre-main sequence stars without disks, which represent ideal photospheric templates for studies of young stars. We also use these spectra to constrain the impact of chromospheric emission on the measurements of mass accretion rates. The spectra are reduced, flux-calibrated, and corrected for telluric absorption, and are made available to the community. We derive the spectral type for our targets by analyzing the photospheric molecular features present in their VLT/X-Shooter spectra by means of spectral indices and comparison of the relative strength of photospheric absorption features. We also measure effective temperature, gravity, projected rotational velocity, and radial velocity from our spectra by fitting them with synthetic spectra with the ROTFIT tool.The targets have negligible extinction (AV<0.5mag) and spectral type from G5 to K6, and from M6.5 to M8. They thus complement the library of photospheric templates presented in our previous paper. We perform synthetic photometry on the spectra to derive the typical colors of young stars in different filters. We measure the luminosity of the emission lines present in the spectra and estimate the noise due to chromospheric emission in the measurements of accretion luminosity in accreting stars. Results. We provide a calibration of the photospheric colors of young pre-main sequence stars as a function of their spectral type in a set of standard broad-band optical and near-infrared filters. The logarithm of the noise on the accretion luminosity normalized to the stellar luminosity is roughly constant and equal to -2.3 for targets with masses larger than 1 solar mass, and decreases with decreasing temperatures for lower-mass stars. For stars with masses of 1.5Msun and ages of 1-5Myr, the chromospheric noise converts to a limit of measurable mass accretion rates of 3x10^-10^M_{sun}_/yr. The limit on the mass accretion rate set by the chromospheric noise is of the order of the lowest measured values of mass accretion rates in Class II objects.
- 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/A+A/361/1143
- Title:
- Proper motions of PMS stars
- Short Name:
- J/A+A/361/1143
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present proper motion measurements of pre-main sequence (PMS) stars associated with major star-forming regions of the southern hemisphere (Chamaeleon, Lupus, Upper Scorpius - Ophiuchus, Corona Australis), situated in the galactic longitude range l=290{deg} to l=360{deg}. A list of PMS stars as complete as possible was established based on the Herbig and Bell (1988LicOB1111....1H) catalogue and many new catalogues like the PDS survey, the catalogue of Herbig Ae/Be stars by The et al. (1994A&AS..104..315T), X-rays surveys, etc. The measurements made use of public material (mainly AC2000 and USNO-A2.0 catalogues) as well as scans of SERC-J Schmidt plates with the MAMA measuring machine (Paris) and Valinhos CCD meridian circle observations (Brazil). We derived proper motions for 213 stars, with an accuracy of 5 to 10mas/yr depending mainly on the difference of epochs between the position sources. The main characteristics of the sample are discussed. We show that systematic motions of groups of stars exist, which are not explained by the reflex solar motion.
- ID:
- ivo://CDS.VizieR/J/AJ/134/411
- Title:
- Properties of IC 348 members
- Short Name:
- J/AJ/134/411
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Spitzer mid-infrared surveys enable an accurate census of young stellar objects by sampling large spatial scales, revealing very embedded protostars, and detecting low-luminosity objects. Taking advantage of these capabilities, we present a Spitzer-based census of the IC 348 nebula and embedded star cluster, covering a 2.5pc region and comparable in extent to the Orion Nebula. Our Spitzer census supplemented with ground-based spectra has added 42 Class II T Tauri sources to the cluster membership and identified ~20 Class 0/I protostars. The population of IC 348 likely exceeds 400 sources after accounting statistically for unidentified diskless members. Our Spitzer census of IC 348 reveals a population of Class I protostars that is anticorrelated spatially with the Class II/III T Tauri members, which comprise the centrally condensed cluster around a B star.
- ID:
- ivo://CDS.VizieR/J/AJ/155/44
- Title:
- Properties of PMS stars in young cluster Berkeley 59
- Short Name:
- J/AJ/155/44
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Berkeley 59 is a nearby (~1 kpc) young cluster associated with the Sh2-171 H II region. We present deep optical observations of the central ~2.5x2.5 pc^2^ area of the cluster, obtained with the 3.58 m Telescopio Nazionale Galileo. The V/(V-I) color-magnitude diagram manifests a clear pre-main-sequence (PMS) population down to ~0.2 M_{sun}_. Using the near-infrared and optical colors of the low-mass PMS members, we derive a global extinction of A_V_=4 mag and a mean age of ~1.8 Myr, respectively, for the cluster. We constructed the initial mass function and found that its global slopes in the mass ranges of 0.2-28 M_{sun}_ and 0.2-1.5 M_{sun}_ are -1.33 and -1.23, respectively, in good agreement with the Salpeter value in the solar neighborhood. We looked for the radial variation of the mass function and found that the slope is flatter in the inner region than in the outer region, indicating mass segregation. The dynamical status of the cluster suggests that the mass segregation is likely primordial. The age distribution of the PMS sources reveals that the younger sources appear to concentrate close to the inner region compared to the outer region of the cluster, a phenomenon possibly linked to the time evolution of star-forming clouds. Within the observed area, we derive a total mass of ~10^3^ M_{sun}_ for the cluster. Comparing the properties of Berkeley 59 with other young clusters, we suggest it resembles more closely the Trapezium cluster.
- ID:
- ivo://CDS.VizieR/J/A+A/640/A27
- Title:
- Protoplanetary disk masses in NGC 2024
- Short Name:
- J/A+A/640/A27
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Protoplanetary disks in dense, massive star-forming regions (SFRs) are strongly affected by their environment. How this environmental impact changes over time is an important constraint on disk evolution and external photoevaporation models. We characterized the dust emission from 179 disks in the core of the young (0.5Myr) NGC 2024 cluster. By studying how the disk mass varies within the cluster, and comparing these disks to those in other regions, we determined how external photoevaporation influences disk properties over time. Using the Atacama Large Millimeter/submillimeter Array (ALMA), a 2.9'x2.9' mosaic centered on NGC 2024 FIR 3 was observed at 225GHz with a resolution of 0.25'', or ~100AU. It contains 179 disks identified at IR wavelengths, 7 new disk candidates, and several protostars. Of the disks in the sample, 57 are detected. The overall detection rate is 32+/-4%. Few of the disks are resolved, with the exception of a giant (R=300AU) transition disk. Serendipitously, we observe a millimeter flare from an X-ray bright Young Stellar Object (YSO), and resolve continuum emission from a Class 0 YSO in the FIR 3 core. Two distinct disk populations are present: a more massive one in the east, along the dense molecular ridge hosting the FIR 1-5 YSOs, with a detection rate of 45+/-7%. In the western population, towards IRS 1, only 15+/-4% of disks are detected. NGC 2024 hosts two distinct disk populations. Disks along the dense molecular ridge are young (0.2-0.5Myr) and partly shielded from the FUV radiation of IRS 2b; their masses are similar to isolated 1-3Myr old SFRs. The western population is older and at lower extinctions, and may be affected by external photoevaporation from both IRS 1 and IRS 2b. It is, however, possible these disks had lower masses to begin with.
- ID:
- ivo://CDS.VizieR/J/ApJ/709/L114
- Title:
- Protoplanetary disks in PMS binaries
- Short Name:
- J/ApJ/709/L114
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this Letter, I examine several observational trends regarding protoplanetary disks, debris disks, and exoplanets in binary systems in an attempt to constrain the physical mechanisms of planet formation in such a context. Binaries wider than about 100AU are indistinguishable from single stars in all aspects. Binaries in the 5-100AU range, on the other hand, are associated with shorter lived but (at least in some cases) equally massive disks. Furthermore, they form planetesimals and mature planetary systems at a similar rate as wider binaries and single stars, albeit with the peculiarity that they predominantly produce high-mass planets. I posit that the location of a stellar companion influences the relative importance of the core accretion and disk fragmentation planet formation processes, with the latter mechanism being predominant in binaries tighter than 100AU.
- ID:
- ivo://CDS.VizieR/J/MNRAS/357/345
- Title:
- Pulsating pre-main-sequence stars in NGC6383
- Short Name:
- J/MNRAS/357/345
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A search for pulsating pre-main-sequence (PMS) stars was performed in the young open cluster NGC 6383 using CCD time-series photometry in Johnson B and V filters. With an age of only ~1.7Myr all cluster members later than spectral type A0 have not reached the ZAMS yet, hence being ideal candidates for investigating PMS pulsation among A- and F-type stars. In total 286 stars have been analysed using classical Fourier techniques. From about a dozen stars within the boundaries of the classical instability strip, two stars were found to pulsate: NGC 6383 #170, with five frequencies simultaneously, and NGC 6383 #198, with a single frequency. In addition, NGC 6383 #152 is a suspected PMS variable star, but our data remain inconclusive. Linear, non-adiabatic models assuming PMS evolutionary phase and purely radial pulsation were calculated for the two new PMS pulsators. NGC 6383 #170 appears to pulsate radially in third and fifth overtones, while the other three frequencies seem to be of non-radial nature. NGC 6383 #198 pulsates mono-periodically, most probably in the third radial overtone. Magnitudes and BV colours were available in the literature for only one third of all stars and we used them for calibrating the remaining.
- ID:
- ivo://CDS.VizieR/J/MNRAS/413/2689
- Title:
- PV Cep V(RI)c and IRAC photometry
- Short Name:
- J/MNRAS/413/2689
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Young Sun-like stars at the beginning of the pre-main-sequence (PMS) evolution are surrounded by accretion discs and remnant protostellar envelopes. Photometric and spectroscopic variations of these stars are driven by interactions of the star with the disc. Time-scales and wavelength dependence of the variability carry information on the physical mechanisms behind these interactions. We conducted multi-epoch, multiwavelength study of PV Cep, a strongly variable, accreting PMS star. By combining our own observations from 2004 to 2010 with archival and literature data, we show that PV Cep started a spectacular fading in 2005, reaching an IC-band amplitude of 4mag. Analysis of variation of the optical and infrared fluxes, colour indices and emission line fluxes suggests that the photometric decline in 2005-2009 resulted from an interplay between variable accretion and circumstellar extinction: since the central luminosity of the system is dominated by accretion, a modest drop in the accretion rate could induce the drastic restructuring of the inner disc. Dust condensation in the inner disc region might have resulted in the enhancement of the circumstellar extinction.
