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15961. Trumpler 14 and 16 in the Carina nebula
ID:
ivo://CDS.VizieR/J/A+A/603/A81
Title:
Trumpler 14 and 16 in the Carina nebula
Short Name:
J/A+A/603/A81
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the first extensive spectroscopic study of the global population in star clusters Trumpler 16, Trumpler 14, and Collinder 232 in the Carina nebula, using data from the Gaia-ESO Survey, down to solar-mass stars. In addition to the standard homogeneous survey data reduction, a special processing was applied here because of the bright nebulosity surrounding Carina stars. We find about 400 good candidate members ranging from OB types down to slightly subsolar masses. About 100 heavily reddened early-type Carina members found here were previously unrecognized or poorly classified, including two candidate O stars and several candidate Herbig Ae/Be stars. Their large brightness makes them useful tracers of the obscured Carina population. The spectroscopically derived temperatures for nearly 300 low-mass members enables the inference of individual extinction values and the study of the relative placement of stars along the line of sight. We find a complex spatial structure with definite clustering of low-mass members around the most massive stars and spatially variable extinction. By combining the new data with existing X-ray data, we obtain a more complete picture of the three-dimensional spatial structure of the Carina clusters and of their connection to bright and dark nebulosity and UV sources. The identification of tens of background giants also enables us to determine the total optical depth of the Carina nebula along many sightlines. We are also able to put constraints on the star formation history of the region with Trumpler 14 stars found to be systematically younger than stars in other subclusters. We find a large percentage of fast-rotating stars among Carina solar-mass members, which provide new constraints on the rotational evolution of pre-main-sequence stars in this mass range.
15962. Trumpler 16 in the CCCP
ID:
ivo://CDS.VizieR/J/ApJS/194/12
Title:
Trumpler 16 in the CCCP
Short Name:
J/ApJS/194/12
Date:
21 Oct 2021
Publisher:
CDS
Description:
Trumpler 16 is a well-known rich star cluster containing the eruptive supergiant {eta} Carinae and located in the Carina star-forming complex. In the context of the Chandra Carina Complex Project, we study Trumpler 16 using new and archival X-ray data. A revised X-ray source list of the Trumpler 16 region contains 1232 X-ray sources including 1187 likely Carina members. These are matched to 1047 near-infrared counterparts detected by the HAWK-I instrument at the Very Large Telescope allowing for better selection of cluster members. The cluster is irregular in shape. Although it is roughly circular, there is a high degree of sub-clustering, with no noticeable central concentration and an extension to the southeast. We estimate the total Trumpler 16 pre-main-sequence population to be >6500 Class II and Class III X-ray sources. An overall K-excess disk frequency of ~8.9% is derived using the X-ray-selected sample, although there is some variation among the sub-clusters, especially in the southeastern extension. X-ray emission is detected from 29 high-mass stars with spectral types between B2 and O3.
15963. Trumpler 14 JHKL' photometry
ID:
ivo://CDS.VizieR/J/A+A/476/199
Title:
Trumpler 14 JHKL' photometry
Short Name:
J/A+A/476/199
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the deepest and highest resolution near-infrared imaging to date of cluster Trumpler 14 in Carina. Our goal is to identify and characterise the young stellar population of this massive cluster. We made use of deep and wide-field NIR images from NTT and VLT observations, that were sensitive enough to detect substellar sources at the distance to this cluster, and at high enough resolution (VLT diffraction limited) to fully resolve the core of the cluster crowded with O stars.
15964. Trumpler 5 photometric BV catalog
ID:
ivo://CDS.VizieR/J/MNRAS/446/1411
Title:
Trumpler 5 photometric BV catalog
Short Name:
J/MNRAS/446/1411
Date:
21 Oct 2021
Publisher:
CDS
Description:
As part of a long-term programme, we analyse the evolutionary status and properties of the old and populous open cluster Trumpler 5 (Tr 5), located in the Galactic anticentre direction, almost on the Galactic plane. Tr 5 was observed with Wide Field Imager@MPG/ESO Telescope using the Bessel U, B, and V filters. The cluster parameters have been obtained using the synthetic colour-magnitude diagram (CMD) method, i.e. the direct comparison of the observational CMD with a library of synthetic CMDs generated with different stellar evolution sets (Padova, FRANEC, and FST). Age, reddening, and distance are derived through the synthetic CMD method using stellar evolutionary models with subsolar metallicity (Z=0.004 or Z=0.006). Additional spectroscopic observations with Ultraviolet VLT Echelle Spectrograph@Very Large Telescope of three red clump stars of the cluster were used to determine more robustly the chemical properties of the cluster. Our analysis shows that Tr 5 has subsolar metallicity, with [Fe/H]=-0.403+/-0.006 dex (derived from spectroscopy), age between 2.9 and 4 Gyr (the lower age is found using stellar models without core overshooting), reddening E(B-V) in the range 0.60-0.66 mag complicated by a differential pattern (of the order of ~+/-0.1mag), and distance modulus (m-M)_0_=12.4+/-0.1mag.
15965. T Tauri binary systems orbital motion
ID:
ivo://CDS.VizieR/J/A+A/369/249
Title:
T Tauri binary systems orbital motion
Short Name:
J/A+A/369/249
Date:
21 Oct 2021
Publisher:
CDS
Description:
Using speckle-interferometry we have carried out repeated measurements of relative positions for the components of 34 T Tauri binary systems. The projected separation of these components is low enough that orbital motion is expected to be observable within a few years. In most cases orbital motion has indeed been detected. The observational data is discussed in a manner similar to Ghez et al. (1995AJ....110..753G). However, we extend their study to a larger number of objects and a much longer timespan. The database presented in this paper is valuable for future visual orbit determinations. It will yield empirical masses for T Tauri stars that now are only poorly known. The available data is however not sufficient to do this at the present time. Instead, we use short series of orbital data and statistical distributions of orbital parameters to derive an average system mass that is independent of theoretical assumptions about the physics of PMS stars. For our sample this mass is and thus in the order of magnitude one expects for the mass sum of two T Tauri stars. It is also comparable to mass estimates obtained for the same systems using theoretical PMS evolutionary models.
15966. T Tauri in and around bright-rimmed clouds
ID:
ivo://CDS.VizieR/J/MNRAS/396/964
Title:
T Tauri in and around bright-rimmed clouds
Short Name:
J/MNRAS/396/964
Date:
21 Oct 2021
Publisher:
CDS
Description:
The aim of this paper is to quantitatively testify the 'small-scale sequential star formation' hypothesis in and around bright-rimmed clouds (BRCs). As a continuation of the recent attempt by Ogura et al. (2007PASJ...59..199O), we have carried out BVIc photometry of four more BRC aggregates along with deeper re-observations of two previously observed BRCs. Again, quantitative age gradients are found in almost all the BRCs studied in the present work. Archival Spitzer/Infrared Array Camera data also support this result.
15967. T Tauri in NGC 2264 cluster
ID:
ivo://CDS.VizieR/J/A+A/629/A67
Title:
T Tauri in NGC 2264 cluster
Short Name:
J/A+A/629/A67
Date:
21 Oct 2021
Publisher:
CDS
Description:
Understanding disk dissipation is essential for studying how planets form. Disk gaps and holes, which almost correspond to dust-free regions, are inferred from infrared observations of T Tauri stars (TTS), indicating the existence of a transitional phase between thick accreting disks and debris disks. Transition disks are usually referred to as candidates for newly formed planets. We searched for transition disk candidates belonging to NGC 2264. Using stellar and disk parameters obtained in the observational multiwavelength campaign CSI 2264, we characterized accretion, disk, and stellar properties of transition disk candidates and compared them to systems with a full disk and diskless stars. We modeled the spectral energy distribution (SED) of a sample of 401 TTS, observed with both CFHT equipped with MegaCam and IRAC instrument on the Spitzer, with Hyperion SED fitting code using photometric data from the U band (0.3um) to the Spitzer/MIPS 24um band. We used the SED modeling to distinguish transition disk candidates, full disk systems, and diskless stars. We classified ~52% of the sample as full disk systems, ~41% as diskless stars, and ~7% of the systems as transition disk candidates, among which seven systems are new transition disk candidates belonging to the NGC 2264 cluster. The sample of transition disk candidates present dust in the inner disk similar to anemic disks, according to the {alpha}_IRAC_ classification, which shows that anemic disk systems can be candidate transition disks. We show that the presence of a dust hole in the inner disk does not stop the accretion process since 82% of transition disk candidates accrete and show H{alpha}, UV excess, and mass accretion rates at the same level as full disk systems. We estimate the inner hole sizes, ranging from 0.1 to 78AU, for the sample of transition disk candidates. In only ~18% of the transition disk candidates, the hole size could be explained by X-ray photoevaporation from stellar radiation.
15968. T Tauri star IR excesses & Ha eq. widths
ID:
ivo://CDS.VizieR/J/ApJ/893/56
Title:
T Tauri star IR excesses & Ha eq. widths
Short Name:
J/ApJ/893/56
Date:
19 Jan 2022 11:42:19
Publisher:
CDS
Description:
We present a study of the evolution of the inner few astronomical units of protoplanetary disks around low-mass stars. We consider nearby stellar groups with ages spanning from 1 to 11Myr, distributed into four age bins. Combining PANSTARSS photometry with spectral types, we derive the reddening consistently for each star, which we use (1) to measure the excess emission above the photosphere with a new indicator of IR excess and (2) to estimate the mass accretion rate (dM/dt) from the equivalent width of the H{alpha} line. Using the observed decay of dM/dt as a constraint to fix the initial conditions and the viscosity parameter of viscous evolutionary models, we use approximate Bayesian modeling to infer the dust properties that produce the observed decrease of the IR excess with age, in the range between 4.5 and 24{mu}m. We calculate an extensive grid of irradiated disk models with a two-layered wall to emulate a curved dust inner edge and obtain the vertical structure consistent with the surface density predicted by viscous evolution. We find that the median dust depletion in the disk upper layers is {epsilon}~3x10^-3^ at 1.5Myr, consistent with previous studies, and it decreases to {epsilon}~3x10^-4^ by 7.5Myr. We include photoevaporation in a simple model of the disk evolution and find that a photoevaporative wind mass-loss rate of ~1-3x10^-9^M_{sun}_/yr agrees with the decrease of the disk fraction with age reasonably well. The models show the inward evolution of the H_2_O and CO snowlines.
15969. T Tauri star population in Lupus
ID:
ivo://CDS.VizieR/J/A+A/580/A26
Title:
T Tauri star population in Lupus
Short Name:
J/A+A/580/A26
Date:
21 Oct 2021
Publisher:
CDS
Description:
In a recent study, we derived individual distances for 109 pre-main sequence stars that define the Lupus kinematic association of young stars. Here, we use these new distances to derive the masses and ages of Lupus T Tauri stars with the aim of better constraining the lifetime of their circumstellar disks. Using the photometric and spectroscopic information available in the literature, we computed the photospheric luminosity of 92 T Tauri stars in the Lupus association. Then, we estimated their masses and ages from theoretical evolutionary models. Based on Monte Carlo simulations and statistical tests, we compare the mass and age distribution of the classical T Tauri stars (CTTS) and weak-line T Tauri (WTTS) in our sample. We show that the CTTSs are on average younger than the WTTSs and that the probability that both T Tauri subclasses are drawn from the same mass and age parental distribution is very low. Our results favor the scenario proposed earlier for the Taurus-Auriga association, where the CTTSs evolve into WTTSs when their disks are fully accreted by the star. Based on an empirical disk model, we find that the average disk lifetime for the T Tauri stars in the Lupus association is {tau}_d_=3x10^6^(M_*_/M_{sun}_)^0.55^yr. We find evidence that the average lifetime of the circumstellar disks in the Lupus association is shorter than in the Taurus-Auriga association and discuss the implications of this result.
15970. 33 T Tauri stars in Taurus Halpha measurements
ID:
ivo://CDS.VizieR/J/MNRAS/469/1783
Title:
33 T Tauri stars in Taurus Halpha measurements
Short Name:
J/MNRAS/469/1783
Date:
21 Oct 2021
Publisher:
CDS
Description:
We conducted a 12-month monitoring campaign of 33 T Tauri stars (TTS) in Taurus. Our goal was to monitor objects that possess a disc but have a weak H{alpha} line, a common accretion tracer for young stars, in order to determine whether they host a passive circumstellar disc. We used medium-resolution optical spectroscopy to assess the accretion status of the objects and to measure the H{alpha} line. We found no convincing examples of passive discs: only transition disc and debris disc systems in our sample are non-accreting. Among accretors, we found no example of flickering accretion, leading to an upper limit of 2.2 per cent on the duty cycle of accretion gaps, assuming that all accreting TTS experience such events. When combining literature results with our observations, we found that the reliability of traditional H{alpha}-based criteria to test for accretion is high but imperfect, particularly for low-mass TTS. We found a significant correlation between stellar mass and the full width at 10 per cent of the peak (W_10_) of the H{alpha} line that does not seem to be related to variations in free-fall velocity. Finally, our data revealed a positive correlation between the H{alpha} equivalent width and its W_10_, indicative of a systematic modulation in the line profile whereby the high-velocity wings of the line are proportionally more enhanced than its core when the line luminosity increases. We argue that this supports the hypothesis that the mass accretion rate on the central star is correlated with the H{alpha} W_10_ through a common physical mechanism.

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