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15971. T Tauri stars in the Sco-Cen OB association
ID:
ivo://CDS.VizieR/J/A+A/356/541
Title:
T Tauri stars in the Sco-Cen OB association
Short Name:
J/A+A/356/541
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report the results of a search for binarity among young stars, performed in the Scorpius-Centaurus OB association on a sample of 118 X-ray selected T Tauri stars. We use speckle interferometry and direct-imaging observations to find companions in the separation range 0.13-6". After corrections to account for confusion with background stars and for the bias induced by the X-ray selection, we find a multiplicity (number of binaries or multiples divided by number of systems) of 32.6+/-6.1)%, and a number of companions per system of (35.2+/-6.3)%. This is higher by a factor of 1.59+/-0.34 compared to main-sequence stars, but slightly lower than in a sample in the Taurus-Auriga star-forming region that was selected and studied similary. In Scorpius-Centaurus, we find fewer binaries with nearly equal brightness than in Taurus-Auriga. There are significant differences between the period distributions in the two subgroups Upper Scorpius A and B: The peak of the distribution of stars in US-A is at about 10^5^ days, while that of stars in US-B is around 10^6.5^ days. We compared our results with the optical multiplicity survey of Brandner et al. (1996A&A...307..121B), whose sample contains 49 stars that were also observed by us, and find no infrared companions. The flux ratio distributions of close and wide binaries in our sample show no significant difference.
15972. T Tauri stars ROSAT survey
ID:
ivo://CDS.VizieR/J/A+A/297/391
Title:
T Tauri stars ROSAT survey
Short Name:
J/A+A/297/391
Date:
21 Oct 2021
Publisher:
CDS
Description:
We study the X-ray emission of T Tauri stars (TTS) in Taurus-Auriga as observed with the spatially unbiased flux-limited ROSAT All-Sky Survey.
15973. T Tauri stars X-ray/accretion anti correlation
ID:
ivo://CDS.VizieR/J/A+A/587/A81
Title:
T Tauri stars X-ray/accretion anti correlation
Short Name:
J/A+A/587/A81
Date:
21 Oct 2021
Publisher:
CDS
Description:
Depending on whether a T Tauri star accretes material from its circumstellar disk or not, different X-ray emission properties can be found. The accretion shocks produce cool heating of the plasma, contributing to the soft X-ray emission from the star. Using X-ray data from the Chandra Orion Ultra-deep Project and accretion rates that were obtained with the Hubble Space Telescope/WFPC2 photometric measurements in the Orion Nebula Cluster, we studied the relation between the accretion processes and the X-ray emissions of a coherent sample of T Tauri sources in the region. We performed regression and correlation analyses of our sample of T Tauri stars between the X-ray parameters, stellar properties, and the accretion measurements. We find that a clear anti-correlation is present between the residual X-ray luminosity and the accretion rates in our samples in Orion that is consistent with that found on the XMM-Newton Extended Survey of the Taurus molecular cloud (XEST) study. A considerable number of classified non-accreting sources show accretion rates comparable to those of classical T Tauri Stars (CTTS). Our data do not allow us to confirm the classification between classical and weak-line T Tauri stars (WTTS), and the number of WTTS in this work is small compared to the complete samples. Thus, we have used the entire samples as accretors in our analysis. We provide a catalog with X-ray luminosities (corrected from distance) and accretion measurements of an Orion Nebula Cluster (ONC) T Tauri stars sample.
15974. T Tau Stars
ID:
ivo://CDS.VizieR/J/A+A/326/211
Title:
T Tau Stars
Short Name:
J/A+A/326/211
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present results of a study to investigate the spatial distribution of X-ray active young stellar objects near the Lupus star forming region (SFR). In this SFR, a recent study has led to the discovery of some 130 new weak-line T Tauri stars (WTTS) dispersed over a large area of some 230 square degrees. However, the true extent of the spatial distribution of these stars could not be determined in this study.
15975. T Tau stars toward the Taurus-Auriga region
ID:
ivo://CDS.VizieR/J/A+A/519/A83
Title:
T Tau stars toward the Taurus-Auriga region
Short Name:
J/A+A/519/A83
Date:
21 Oct 2021
Publisher:
CDS
Description:
We search for new T Tauri star (TTS) candidates with the mid-infrared (MIR) part of the AKARI All-Sky Survey at 9 and 18{mu}m wavelengths. We used the point source catalogue (PSC) obtained by the Infrared Camera (IRC) on board AKARI. We combined the 2MASS PSC and the 3rd version of the USNO CCD Astrograph Catalogue (UCAC) with the AKARI IRC-PSC, and surveyed 517 known TTSs over a 1800-square-degree part of the Taurus-Auriga region to develop criteria to extract TTSs. We considered asymptotic giant branch (AGB) stars, post-AGB stars, planetary nebulae (PNe), and galaxies, which have similar MIR colours, to separate TTSs from these sources. We finally searched for new TTS candidates from AKARI IRC-PSC in the same Taurus-Auriga region. Of the 517 known TTSs, we detected 133 sources with AKARI: 46 sources were not detected by IRAS. Based on the colour-colour and colour-magnitude diagrams made from the AKARI, 2MASS, and UCAC surveys, we propose the criteria to extract TTS candidates from the AKARI All-Sky data, and 68/133 AKARI detected TTSs have passed these criteria. On the basis of our criteria, we selected 176/14725 AKARI sources as TTS candidates that are located around the Taurus-Auriga region. Comparing these sources with SIMBAD, we found that 148 are previously identified sources including 115 young stellar objects (YSOs), and 28 unidentified sources. Based on SIMBAD identifications, we infer the TTS-identification probability using our criteria to be ~75%. We find 28 TTS candidates, of which we expect ~21 to be confirmed once follow-up observations can be obtained. Although the probability of ~75% is not so high, it is affected by the completeness of the SIMBAD database, and we can search for TTSs over the whole sky, and all star-forming regions.
15976. [TT2009] 25 vicinity VI photometry
ID:
ivo://CDS.VizieR/J/A+A/629/L2
Title:
[TT2009] 25 vicinity VI photometry
Short Name:
J/A+A/629/L2
Date:
21 Oct 2021
Publisher:
CDS
Description:
Dwarf galaxies are key objects for small-scale cosmological tests like the abundance problems or the planes-of-satellites problem. A crucial task is therefore to get accurate information for as many nearby dwarf galaxies as possible. Using extremely deep, groundbased V and i-band Subaru Suprime Cam photometry with a completeness of i=27mag, we measure the distance of the dwarf galaxy [TT2009] 25 using the tip of the red giant branch (RGB) as a standard candle. This dwarf resides in the field around the Milky Way-analog NGC891. Using a Bayesian approach, we measure a distance of 10.28Mpc, which is consistent with the distance of NGC891, and thus confirm it as a member of NGC891. The dwarf galaxy follows the scaling relations defined by the Local Group dwarfs. We do not find an extended stellar halo around [TT2009] 25. In the small field of view of 100kpc covered by the survey, only one bright dwarf galaxy and the giant stream are apparent. This is comparable to the Milky Way, where one bright dwarf resides in the same volume, as well as the Sagittarius stream - excluding satellites which are farther away but would be projected in the line-of-sight. It is thus imperative to survey for additional dwarf galaxies in a larger area around NGC891 to test the abundance of dwarf galaxies and compare this to the number of satellites around the Milky Way.
15977. TTVs from Kepler. VI. Statistical tests
ID:
ivo://CDS.VizieR/J/ApJ/756/186
Title:
TTVs from Kepler. VI. Statistical tests
Short Name:
J/ApJ/756/186
Date:
21 Oct 2021
Publisher:
CDS
Description:
We analyze the deviations of transit times from a linear ephemeris for the Kepler Objects of Interest (KOI) through quarter six of science data. We conduct two statistical tests for all KOIs and a related statistical test for all pairs of KOIs in multi-transiting systems. These tests identify several systems which show potentially interesting transit timing variations (TTVs). Strong TTV systems have been valuable for the confirmation of planets and their mass measurements. Many of the systems identified in this study should prove fruitful for detailed TTV studies.
15978. TTVs & linear ephemerides of Kepler exoplanets
ID:
ivo://CDS.VizieR/J/other/RAA/19.41
Title:
TTVs & linear ephemerides of Kepler exoplanets
Short Name:
J/other/RAA/19.4
Date:
21 Oct 2021
Publisher:
CDS
Description:
We determined new linear ephemerides of transiting exoplanets using long-cadence de-trended data from quarters Q1 to Q17 of Kepler mission. We analysed TTV diagrams of 2098 extrasolar planets. The TTVs of 121 objects were excluded (because of insufficient data-points, influence of stellar activity, etc). Finally, new linear ephemerides of 1977 exoplanets from Kepler archive are presented. The significant linear trend was observed on TTV diagrams of approximately 35% of studied exoplanets. Knowing correct linear ephemeris is principal for successful follow-up observations of transits. Residual TTV diagrams of 64 analysed exoplanets shows periodic variation, 43 of these TTV planets were not reported yet.
15979. Tubingen Echelle Spectrograph
ID:
ivo://archive.stsci.edu/tues
Title:
Tubingen Echelle Spectrograph
Short Name:
TUES
Date:
22 Jul 2020 21:31:05
Publisher:
Space Telescope Science Institute Archive
Description:
The Tübingen Echelle (TUES) obtained moderate dispersion observations (R=13,000) using an echelle grating including orders 40 - 61 from 910 - 1410 Angstroms. The instrument was designed and built by the University of Tübingen (PI: M. Grewing) and flew as one of three spectrographs on the ORFEUS/SPAS-2 mission for 14 days in November/December 1996. The instrumental resolution was about 10,000 and the effective aperture peaks at 1.3 cm2 near 1100 Angstroms. Objects were observed in a 10 arcsec entrance aperture. The wavelength calibration was established by means of interstellar molecular hydrogen lines.
15980. Tubingen Ultraviolet Echelle Spectrometer
ID:
ivo://CDS.VizieR/VI/107
Title:
Tubingen Ultraviolet Echelle Spectrometer
Short Name:
VI/107
Date:
21 Oct 2021
Publisher:
CDS
Description:
The Tubingen Echelle Spectrograph (TUES), designed and managed at the University of Tubingen, flew on the Orbiting and Retrievable Far and Extreme Ultraviolet Spectrograph (ORFEUS)-SPAS II space shuttle mission in 1996, returning spectra in the 900 Angstrom to 1400 Angstrom wavelength range. The instrument was designed to achieve a spectral resolution of 10000 when used with an entrance aperture of 10" diameter. During the 17.7 day flight, TUES returned 239 spectra of 62 targets.

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