- ID:
- ivo://CDS.VizieR/J/ApJS/186/259
- Title:
- Taurus Spitzer survey: new candidate members
- Short Name:
- J/ApJS/186/259
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report on the properties of pre-main-sequence objects in the Taurus molecular clouds as observed in seven mid- and far-infrared bands with the Spitzer Space Telescope. There are 215 previously identified members of the Taurus star-forming region in our ~44deg^2^ map; these members exhibit a range of Spitzer colors that we take to define young stars still surrounded by circumstellar dust (noting that ~20% of the bona fide Taurus members exhibit no detectable dust excesses). We looked for new objects in the survey field with similar Spitzer properties, aided by extensive optical, X-ray, and ultraviolet imaging, and found 148 new candidate members of Taurus. We have obtained follow-up spectroscopy for about half the candidate sample, thus far confirming 34 new members, three probable new members, and 10 possible new members, an increase of 15%-20% in Taurus members. Of the objects for which we have spectroscopy, seven are now confirmed extragalactic objects, and one is a background Be star. The remaining 93 candidate objects await additional analysis and/or data to be confirmed or rejected as Taurus members. Most of the new members are Class II M stars and are located along the same cloud filaments as the previously identified Taurus members. Among non-members with Spitzer colors similar to young, dusty stars are evolved Be stars, planetary nebulae, carbon stars, galaxies, and active galactic nuclei.
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Search Results
21392. Taurus ultra-wide pairs
- ID:
- ivo://CDS.VizieR/J/A+A/599/A14
- Title:
- Taurus ultra-wide pairs
- Short Name:
- J/A+A/599/A14
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This work analyses the spatial distribution of stars in Taurus with a specific focus on multiple stars and wide pairs in order to derive new constraints on star formation and early dynamical evolution scenarios. We collected the multiplicity data of stars in Taurus to build an up-to-date stellar/multiplicity catalog. We first present a general study of nearest-neighbor statistics on spatial random distribution, comparing its analytical distribution and moments to those obtained from Monte Carlo samplings. We introduce the one-point correlation {Psi} function to complement the pair correlation function and define the spatial regimes departing from randomness in Taurus. We then perform a set of statistical studies to characterize the binary regime that prevails in Taurus. The {Psi} function in Taurus has a scale-free trend with a similar exponent as the correlation function at small scale. It extends almost 3 decades up to ~60kAU showing a potential extended wide binary regime. This was hidden in the correlation function due to the clustering pattern blending. Distinguishing two stellar populations, single stars versus multiple systems (separation <=1kAU), within Class II/III stars observed at high angular resolution, we highlight a major spatial neighborhood difference between the two populations using nearest-neighbor statistics. The multiple systems are three times more likely to have a distant companion within 10kAU when compared to single stars. We show that this is due to the presence of most probable physical ultra-wide pairs (UWPs, defined as such from their mutual nearest neighbor property), that are themselves generally composed of multiple systems containing up to five stars altogether. More generally, our work highlights; 1) a new large population of candidate UWPs in Taurus within the range 1-60kAU in Taurus and 2) the major local structural role they play up to 60kAU. There are three different types of UWPs; either composed of two tight and comparatively massive stars (MM), by one single and one multiple (SM), or by two distant low-mass singles (SS) stars. These UWPs are biased towards high multiplicity and higher-stellar-mass components at shorter separations. The multiplicity fraction per ultra-wide pair with separation less than 10kAU may be as high as 83.5+/-19.6%. We suggest that these young pre-main sequence UWPs may be pristine imprints of their spatial configuration at birth resulting from a cascade fragmentation scenario of the natal molecular core. They could be the older counterparts, at least for those separated by less than 10kAU, to the <=0.5Myr prestellar cores/Class 0 multiple objects observed at radio/millimeter wavelengths.
21393. Taurus ultra-wide pairs. II.
- ID:
- ivo://CDS.VizieR/J/A+A/620/A27
- Title:
- Taurus ultra-wide pairs. II.
- Short Name:
- J/A+A/620/A27
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Multiplicity and clustering of young pre-main sequence stars appear as critical clues to understand and constrain the star formation process. Taurus is the archetypical example of the most quiescent star forming regions that may still retain primeval signatures of star formation. This work identifies local overdense stellar structures as a critical scale between wide pairs and loose groups in Taurus. Using the density-based spatial clustering of applications with noise (dbscan) algorithm, and setting its free parameters based on the one-point correlation function and the k-nearest neighbor statistics, we have extracted reliably overdense structures from the sky-projected spatial distribution of stars. Nearly half of the entire stellar population in Taurus is found to be concentrated in 20 very dense, tiny and prolate regions called NESTs (for Nested Elementary STructures). They are regularly spaced (~2pc) and mainly oriented along the principal gas filaments axes. Each NEST contains between four and 23 stars. Inside NESTs, the surface density of stars may be as high as 2500pc^-2^ and the mean value is 340pc^-2^. Nearly half (11) of these NESTs contain about 75% of the class 0 and I objects. The balance between Class I, II, and, III fraction within the NESTs suggests that they may be ordered as an evolutionary temporal scheme, some of them getting infertile with time, while other still giving birth to young stars. We have inferred that only 20% of stars in Taurus do not belong to any kind of stellar groups (either multiple system, ultra wide pairs or NESTs). The mass-size relation for stellar NESTs is very close to the Bonnor-Ebert expectation. The range in mass is about the same as that of dense molecular cores. The distribution in size is bimodal peaking at 12.5 and 50kAU and the distribution of the number of YSOs in NESTs as a function of size exhibits two regimes. We propose that the NESTs in their two size regimes represent the spatial imprints of stellar distribution at birth as they may have emerged within few millions years from their natal cloud either from a single core or from a chain of cores. We have identified them as the preferred sites of star formation in Taurus. These NESTs are the regions of highest stellar density and intermediate spatial scale structures between ultra-wide pairs and loose groups.
21394. Taverna Execution
- ID:
- ivo://mssl.ucl.ac.uk/Taverna
- Title:
- Taverna Execution
- Short Name:
- Taverna Executi
- Date:
- 29 Jun 2008 16:32:14
- Publisher:
- Astrogrid
- Description:
- Executes a Taverna workflow
21395. Taverna Server
- ID:
- ivo://helio-vo.eu/taverna-server
- Title:
- Taverna Server
- Date:
- 15 Dec 2011 00:14:31
- Publisher:
- Helio
- Description:
- Taverna Server.
- ID:
- ivo://CDS.VizieR/J/A+A/617/A12
- Title:
- Taxonomic classification of asteroids
- Short Name:
- J/A+A/617/A12
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We tabulate the taxonomic classification of 18265 asteroids catalogued by MOVIS. A probabilistic method and the k-nearest neighbors (KNN k=3) algorithm are used to assign a taxonomic type for each object.
21397. Taxonomy of Barium Stars
- ID:
- ivo://CDS.VizieR/V/81
- Title:
- Taxonomy of Barium Stars
- Short Name:
- V/81
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Image-tube spectra and photometric observations for 389 bariums stars have been used to determine spectral classification, barium intensity, radial velocity, luminosity, and kinematical properties. The objective of this study is to obtain a homogeneous dataset for analyzing barium characteristics in uniform fashion.
- ID:
- ivo://CDS.VizieR/J/AJ/151/11
- Title:
- Taxonomy of potentially hazardous asteroids
- Short Name:
- J/AJ/151/11
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Through their delivery of water and organics, near-Earth objects (NEOs) played an important role in the emergence of life on our planet. However, they also pose a hazard to the Earth, as asteroid impacts could significantly affect our civilization. Potentially hazardous asteroids (PHAs) are those that, in principle, could possibly impact the Earth within the next century, producing major damage. About 1600 PHAs are currently known, from an estimated population of 4700+/-1450. However, a comprehensive characterization of the PHA physical properties is still missing. Here we present spectroscopic observations of 14 PHAs, which we have used to derive their taxonomy, meteorite analogs, and mineralogy. Combining our results with the literature, we investigated how PHAs are distributed as a function of their dynamical and physical properties. In general, the ''carbonaceous'' PHAs seem to be particularly threatening, because of their high porosity (limiting the effectiveness of the main deflection techniques that could be used in space) and low inclination and minimum orbit intersection distance (MOID) with the Earth (favoring more frequent close approaches). V-type PHAs also present low MOID values, which can produce frequent close approaches (as confirmed by the recent discovery of a limited space weathering on their surfaces). We also identified those specific objects that deserve particular attention because of their extreme rotational properties, internal strength, or possible cometary nature. For PHAs and NEOs in general, we identified a possible anti-correlation between the elongation and the rotational period, in the range of P_rot_~5-80hr. This would be compatible with the behavior of gravity-dominated aggregates in rotational equilibrium. For periods >~80-90hr, such a trend stops, possibly under the influence of the YORP effect and collisions. However, the statistics is very low, and further observational and theoretical work is required to characterize such slow rotators.
- ID:
- ivo://tmap.iaat
- Title:
- Tübingen NLTE Model Atmosphere (TMAP) authority
- Date:
- 02 Apr 2025 11:46:13
- Publisher:
- The GAVO DC team
- Description:
- This authority is used to assign Creator DIDs to TheoSSA spectra. For historical reasons, these Creator DIDs are not resolvable (we would have to create one registry record per spectrum then). Please consider them opaque strings.
21400. 2015 TB145 light curve
- ID:
- ivo://CDS.VizieR/J/A+A/598/A63
- Title:
- 2015 TB145 light curve
- Short Name:
- J/A+A/598/A63
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The near-Earth asteroid (NEA) 2015 TB145 had a very close encounter with Earth at 1.3 lunar distances on October 31, 2015. We obtained 3-band mid-infrared observations of this asteroid with the ESO VLT-VISIR instrument covering about 4 hours in total. We also monitored the visual lightcurve during the close-encounter phase. The NEA has a (most likely) rotation period of 2.939+/-0.005-hours and the visual lightcurve shows a peak-to-peak amplitude of about 0.12+/-0.02mag. A second rotation period of 4.779+/-0.012h, with an amplitude of the Fourier fit of 0.10+/-0.02mag, also seems compatible with the available lightcurve measurements. We estimate a V-R colour of 0.56+/-0.05mag from different entries in the MPC database. A reliable determination of the object's absolute magnitude was not possible. Applying different phase relations to the available R-/V-band observations produced H_R_=18.6mag (standard H-G calculations) or H_R_=19.2mag and H_V_=19.8mag (via the H-G_12_ procedure for sparse and low-quality data), with large uncertainties of about 1mag. We performed a detailed thermophysical model analysis by using spherical and partially also ellipsoidal shape models. The thermal properties are best explained by an equator-on (+/-~30{deg}) viewing geometry during our measurements with a thermal inertia in the range 250-700J/m^2^/s^0.5^/K (retrograde rotation) or above 500J/m^2^/s^0.5^/K (prograde rotation). We find that the NEA has a minimum size of about 625m, a maximum size of just below 700m, and a slightly elongated shape with a/b~1.1.
