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17951. 12 years positional measurements of 8 binaries
ID:
ivo://CDS.VizieR/J/AJ/159/266
Title:
12 years positional measurements of 8 binaries
Short Name:
J/AJ/159/266
Date:
21 Oct 2021
Publisher:
CDS
Description:
The orbits of eight systems with low-mass components (HIP14524, HIP16025, HIP28671, HIP46199, HIP47791, HIP60444, HIP61100, and HIP73085) are presented. Speckle interferometric data were obtained at the 6m Big Telescope Alt-azimuth Special Astrophysical Observatory of the Russian Academy of Sciences (BTA SAO RAS) from 2007 to 2019. New data, together with measures already in the literature, made it possible to improve upon previous orbital solutions in six cases and to construct orbits for the first time in the two remaining cases (HIP14524 and HIP60444). Mass sums are obtained using both Hipparcos and Gaia parallaxes, and a comparison with previously published values is made. Using the Worley & Heintz criteria, the classification of the orbits constructed is carried out.
17952. 7 year Swift-XRT point source catalog (1SWXRT)
ID:
ivo://CDS.VizieR/J/A+A/551/A142
Title:
7 year Swift-XRT point source catalog (1SWXRT)
Short Name:
J/A+A/551/A142
Date:
21 Oct 2021
Publisher:
CDS
Description:
The Swift satellite is a multi-wavelength observatory specifically designed for gamma-ray burst (GRB) astronomy that is operational since 2004. Swift is also a very flexible multi-purpose facility that supports a wide range of scientific fields such as active galactic nuclei, supernovae, cataclysmic variables, Galactic transients, active stars and comets. The Swift X-ray Telescope (XRT) has collected more than 150Ms of observations in its first seven years of operations. The purpose of this work is to present to the scientific community the list of all the X-ray point sources detected in XRT imaging data taken in photon counting mode during the first seven years of Swift operations. All these point-like sources, excluding the Gamma-Ray Bursts (GRB), will be stored in a catalog publicly available (1SWXRT). We consider all the XRT observations with exposure time longer than 500 s taken in the period 2005-2011. Data were reduced and analyzed with standard techniques and a list of detected sources for each observation was produced. A careful visual inspection was performed to remove extended, spurious and piled-up sources. Finally, positions, count rates, fluxes and the corresponding uncertainties were computed.
17953. Yee et al. 2017
ID:
ivo://svo.cab/cat/yee2017
Title:
Yee et al. 2017
Short Name:
FGKM-Yee2017
Date:
11 Jun 2020 09:42:56
Publisher:
SVO/CAB
Description:
Precision Stellar Characterization of FGKM Stars using an Empirical Spectral Library
17954. Yellow and red supergiants in the LMC
ID:
ivo://CDS.VizieR/J/ApJ/749/177
Title:
Yellow and red supergiants in the LMC
Short Name:
J/ApJ/749/177
Date:
21 Oct 2021
Publisher:
CDS
Description:
Due to their transitionary nature, yellow supergiants (YSGs) provide a critical challenge for evolutionary modeling. Previous studies within M31 and the Small Magellanic Cloud show that the Geneva evolutionary models do a poor job at predicting the lifetimes of these short-lived stars. Here, we extend this study to the Large Magellanic Cloud (LMC) while also investigating the galaxy's red supergiant (RSG) content. This task is complicated by contamination by Galactic foreground stars that color and magnitude criteria alone cannot weed out. Therefore, we use proper-motions and the LMC's large systemic radial velocity (~278km/s) to separate out these foreground dwarfs. After observing nearly 2000 stars, we identified 317 probable YSGs, 6 possible YSGs, and 505 probable RSGs. Foreground contamination of our YSG sample was ~80%, while that of the RSG sample was only 3%. By placing the YSGs on the Hertzsprung-Russell diagram and comparing them against the evolutionary tracks, we find that new Geneva evolutionary models do an exemplary job at predicting both the locations and the lifetimes of these transitory objects.
17955. Yellowballs in Milky Way project
ID:
ivo://CDS.VizieR/J/ApJ/799/153
Title:
Yellowballs in Milky Way project
Short Name:
J/ApJ/799/153
Date:
21 Oct 2021
Publisher:
CDS
Description:
Yellowballs are a collection of approximately 900 compact, infrared sources identified and named by volunteers participating in the Milky Way Project (MWP), a citizen science project that uses GLIMPSE/MIPSGAL images from Spitzer to explore topics related to Galactic star formation. In this paper, through a combination of catalog cross-matching and infrared color analysis, we show that yellowballs are a mix of compact star-forming regions, including ultra-compact and compact HII regions, as well as analogous regions for less massive B-type stars. The resulting MWP yellowball catalog provides a useful complement to the Red MSX Source survey. It similarly highlights regions of massive star formation, but the selection of objects purely on the basis of their infrared morphology and color in Spitzer images identifies a signature of compact star-forming regions shared across a broad range of luminosities and, by inference, masses. We discuss the origin of their striking mid-infrared appearance and suggest that future studies of the yellowball sample will improve our understanding of how massive and intermediate-mass star-forming regions transition from compact to more extended bubble-like structures.
17956. Yellow supergiants in M31
ID:
ivo://CDS.VizieR/J/ApJ/703/441
Title:
Yellow supergiants in M31
Short Name:
J/ApJ/703/441
Date:
21 Oct 2021
Publisher:
CDS
Description:
The yellow supergiant (F- and G-type) content of nearby galaxies can provide a critical test of stellar evolution theory, bridging the gap between the hot, massive stars and the cool red supergiants. But, this region of the color-magnitude diagram is dominated by foreground contamination, requiring membership to somehow be determined. Fortunately, the large negative systemic velocity of M31, coupled to its high rotation rate, provides the means for separating the contaminating foreground dwarfs from the bona fide yellow supergiants within M31. We obtained radial velocities of ~2900 individual targets within the correct color-magnitude range corresponding to masses of 12M_{sun}_ and higher. A comparison of these velocities to those expected from M31's rotation curve reveals 54 rank-1 (near certain) and 66 rank-2 (probable) yellow supergiant members, indicating a foreground contamination >=96%. We expect some modest contamination from Milky Way halo giants among the remainder, particularly for the rank-2 candidates, and indeed follow-up spectroscopy of a small sample eliminates four rank 2's while confirming five others.
17957. Yellow supergiants in the SMC
ID:
ivo://CDS.VizieR/J/ApJ/719/1784
Title:
Yellow supergiants in the SMC
Short Name:
J/ApJ/719/1784
Date:
21 Oct 2021
Publisher:
CDS
Description:
The yellow supergiant content of nearby galaxies provides a critical test of massive star evolutionary theory. While these stars are the brightest in a galaxy, they are difficult to identify because a large number of foreground Milky Way stars have similar colors and magnitudes. We previously conducted a census of yellow supergiants within M31 and found that the evolutionary tracks predict a yellow supergiant duration an order of magnitude longer than we observed. Here we turn our attention to the Small Magellanic Cloud (SMC), where the metallicity is 10x lower than that of M31, which is important as metallicity strongly affects massive star evolution. The SMC's large radial velocity (~160km/s) allows us to separate members from foreground stars. Observations of ~500 candidates yielded 176 near-certain SMC supergiants, 16 possible SMC supergiants, along with 306 foreground stars, and provide good relative numbers of yellow supergiants down to 12M_{sun}_. Of the 176 near-certain SMC supergiants, the kinematics predicted by the Besancon model of the Milky Way suggest a foreground contamination of <=4%. After placing the SMC supergiants on the Hertzsprung-Russell diagram (HRD) and comparing our results to the Geneva evolutionary tracks, we find results similar to those of the M31 study: while the locations of the stars on the HRD match the locations of evolutionary tracks well, the models overpredict the yellow supergiant lifetime by a factor of 10. Uncertainties about the mass-loss rates on the main sequence thus cannot be the primary problem with the models.
17958. YJK for Type Ia supernovae
ID:
ivo://CDS.VizieR/J/MNRAS/448/1345
Title:
YJK for Type Ia supernovae
Short Name:
J/MNRAS/448/1345
Date:
21 Oct 2021
Publisher:
CDS
Description:
Type Ia supernovae (SNe Ia) have been proposed to be much better distance indicators at near-infrared (NIR) compared to optical wavelengths - the effect of dust extinction is expected to be lower and it has been shown that SNe Ia behave more like `standard candles' at NIR wavelengths. To better understand the physical processes behind this increased uniformity, we have studied the Y, J and H-filter light curves of 91 SNe Ia from the literature. We show that the phases and luminosities of the first maximum in the NIR light curves are extremely uniform for our sample. The phase of the second maximum, the late-phase NIR luminosity and the optical light-curve shape are found to be strongly correlated, in particular more luminous SNe Ia reach the second maximum in the NIR filters at a later phase compared to fainter objects. We also find a strong correlation between the phase of the second maximum and the epoch at which the SN enters the Lira law phase in its optical colour curve (epochs ~15 to 30d after B-band maximum). The decline rate after the second maximum is very uniform in all NIR filters. We suggest that these observational parameters are linked to the nickel and iron mass in the explosion, providing evidence that the amount of nickel synthesized in the explosion is the dominating factor shaping the optical and NIR appearance of SNe Ia.
17959. YMGs. I. Young binaries & lithium-rich stars
ID:
ivo://CDS.VizieR/J/ApJ/877/60
Title:
YMGs. I. Young binaries & lithium-rich stars
Short Name:
J/ApJ/877/60
Date:
21 Oct 2021
Publisher:
CDS
Description:
Young stars in the solar neighborhood serve as nearby probes of stellar evolution and represent promising targets to directly image self-luminous giant planets. We have carried out an all-sky search for late-type (~K7-M5) stars within 100pc selected primarily on the basis of activity indicators from the Galaxy Evolution Explorer and ROSAT. Approximately 2000 active and potentially young stars are identified, of which we have followed up over 600 with low-resolution optical spectroscopy and over 1000 with diffraction-limited imaging using Robo-AO at the Palomar 1.5m telescope. Strong lithium is present in 58 stars, implying ages spanning ~10-200Myr. Most of these lithium-rich stars are new or previously known members of young moving groups including TWA, {beta}Pic, Tuc-Hor, Carina, Columba, Argus, ABDor, Upper Centaurus Lupus, and Lower Centaurus Crux; the rest appear to be young low-mass stars without connections to established kinematic groups. Over 200 close binaries are identified down to 0.2"-the vast majority of which are new-and will be valuable for dynamical mass measurements of young stars with continued orbit monitoring in the future.
17960. 12Y-MST and 12Y-MSTw Catalogues
ID:
ivo://CDS.VizieR/J/A+A/652/A6
Title:
12Y-MST and 12Y-MSTw Catalogues
Short Name:
J/A+A/652/A6
Date:
22 Feb 2022
Publisher:
CDS
Description:
We present an updated version catalogue of gamma-ray source candidates, 12Y-MST, selected using the Minimum Spanning Tree (MST) algorithm on the 12-years Fermi/LAT sky (Pass 8) at energies higher than 10GeV. The high energy sky at absolute Galactic latitudes above 20 degrees has been investigated using rather restrictive selection criteria, resulting in a total sample of 1664 photon clusters, or candidate sources. Of these, 230 are new detections, i.e., candidate sources without any association in other gamma-ray catalogues. A large fraction of them have interesting counterparts, most likely blazars. In this paper the main results on the catalogue selection and search of counterparts are described. We also present an additional sample of 224 candidate sources (12Y-MSTw), which are clusters extracted applying weaker selection criteria: about 57% of them have not been reported in other catalogues.

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