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1601. Spectra of 21 late-type stars
ID:
ivo://CDS.VizieR/J/A+AS/117/93
Title:
Spectra of 21 late-type stars
Short Name:
J/A+AS/117/93
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present optical spectra of 21 stars from 4800 to 8920A, covering essentially the late spectral types, G, K, M and the luminosity classes I and III. Half of the stars are super metal rich (SMR) ones. The spectra were obtained at a resolution of 1.25A using the Aurelie spectrograph, equipped with a linear array CCD-like detector, attached to the OHP 1.52m telescope. Also presented are the spectra of 7 stars, covering the region 5000-9783A at a resolution of 8.5A, observed at the CFHT with the Herzberg spectrograph. The spectral types are F, G, K, M and the luminosity classes III and V. Five stars are SMR. These spectra have been obtained with the aim of extending existing libraries used for population synthesis purposes. The inclusion of SMR stars in a stellar library dedicated to the study of stellar populations in the central part of galaxies is crucial as abundance gradients have been observed in the optical range.
1602. Spectra of 13 lensed quasars
ID:
ivo://CDS.VizieR/J/A+A/544/A62
Title:
Spectra of 13 lensed quasars
Short Name:
J/A+A/544/A62
Date:
21 Oct 2021
Publisher:
CDS
Description:
We provide single-epoch spectroscopic data for a sample of 13 lensed quasars. The sources have bolometric luminosities between 10^44.7-47.4^erg/s and black hole masses 10^7.6-9.8^M_{sun}. These spectra have been used to perform a systematic search for microlensing in the broad line region. The spectra have been deblended using the MCS advanced deconvolution technique. We provide the extracted and flux calibrated spectra, and the 2D deconvolved frames, separating the point-like emission from the extended emission (from the residual sky and from the lensing galaxy).
1603. Spectra of low-mass stars in Upper Sco
ID:
ivo://CDS.VizieR/J/A+A/527/A24
Title:
Spectra of low-mass stars in Upper Sco
Short Name:
J/A+A/527/A24
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have obtained multi-fibre intermediate-resolution optical spectroscopy of 94 photometric and proper motion selected low-mass star and brown dwarf candidates in Upper Sco with the AAOmega spectrograph on the Anglo-Australian Telescope. We have estimated the spectral types and measured the equivalent widths of youth and gravity diagnostic features to confirm the spectroscopic membership of about 95% of the photometric and proper motion candidates extracted from 6.5 square degrees surveyed in Upper Sco by the UKIRT Infrared Deep Sky Survey (UKIDSS) Galactic Clusters Survey (GCS). We have estimated the effective temperatures and masses for each new spectroscopic member using the latest evolutionary models available for low-mass stars and brown dwarfs. Combining the current optical spectroscopy presented here with near-infrared spectroscopy obtained for the faintest photometric candidates, we confirm the shape and slope of our earlier photometric mass function. The luminosity function drawn from the spectroscopic sample of 113 USco members peaks at around M6 and is flat at later spectral type. The mass function may peak at 0.2M_{sun}_ and is quite flat in the substellar regime. We observe a possible excess of cool low-mass brown dwarfs compared to IC 348 and the extrapolation of the field mass functions, supporting the original hypothesis that Upper Sco may possess an excess of brown dwarfs compared.
1604. Spectra of 14 Magellanic Cloud planetary nebulae
ID:
ivo://CDS.VizieR/J/A+A/642/A71
Title:
Spectra of 14 Magellanic Cloud planetary nebulae
Short Name:
J/A+A/642/A71
Date:
21 Oct 2021
Publisher:
CDS
Description:
We obtained new spectra of fourteen Magellanic Cloud planetary nebulae with the South African Large Telescope to determine heating rates of their central stars and to verify evolutionary models of post asymptotic giant branch stars. We compared new spectra with observations made in previous years. Five planetary nebulae showed an increase of the excitation with time. Four of their central stars exhibit [WC] features in their spectra, including three new detections. This raises the total number of [WC] central stars of PNe in the Magellanic Clouds to ten. We compared determined heating rates of the four [WC] central stars with the He burning post asymptotic giant branch evolutionary tracks and the remaining star with the H-burning tracks. Determined heating rates are consistent with the evolutionary models for both H and He-burning post asymptotic giant branch stars. The central stars of the PNe which show the fastest increase of excitation are also the most luminous in the sample. This indicates that [WC] central stars in the Magellanic Clouds evolve faster than H-burning central stars and originate from more massive progenitors.
1605. Spectra of nearby late K and M Kepler stars
ID:
ivo://CDS.VizieR/J/ApJ/779/188
Title:
Spectra of nearby late K and M Kepler stars
Short Name:
J/ApJ/779/188
Date:
21 Oct 2021
Publisher:
CDS
Description:
We use moderate-resolution spectra of nearby late K and M dwarf stars with parallaxes and interferometrically determined radii to refine their effective temperatures, luminosities, and metallicities. We use these revised values to calibrate spectroscopic techniques to infer the fundamental parameters of more distant late-type dwarf stars. We demonstrate that, after masking out poorly modeled regions, the newest version of the PHOENIX atmosphere models accurately reproduce temperatures derived bolometrically. We apply methods to late-type hosts of transiting planet candidates in the Kepler field, and calculate effective temperature, radius, mass, and luminosity with typical errors of 57K, 7%, 11%, and 13%, respectively. We find systematic offsets between our values and those from previous analyses of the same stars, which we attribute to differences in atmospheric models utilized for each study. We investigate which of the planets in this sample are likely to orbit in the circumstellar habitable zone. We determine that four candidate planets (KOI 854.01, 1298.02, 1686.01, and 2992.01) are inside of or within 1{sigma} of a conservative definition of the habitable zone, but that several planets identified by previous analyses are not (e.g., KOI 1422.02 and KOI 2626.01). Only one of the four habitable-zone planets is Earth sized, suggesting a downward revision in the occurrence of such planets around M dwarfs. These findings highlight the importance of measuring accurate stellar parameters when deriving parameters of their orbiting planets.
1606. Spectra of 28 nearby young late-M dwarfs
ID:
ivo://CDS.VizieR/J/A+A/600/A19
Title:
Spectra of 28 nearby young late-M dwarfs
Short Name:
J/A+A/600/A19
Date:
21 Oct 2021
Publisher:
CDS
Description:
Late M-type dwarfs in the solar neighborhood include a mixture of very low-mass stars and brown dwarfs that is difficult to disentangle due to the lack of constraints on their age, such as trigonometric parallax, lithium detection, and space velocity. We search for young brown dwarf candidates among a sample of 28 nearby late-M dwarfs with spectral types between M5.0 and M9.0, and we also search for debris disks around three of them. Based on theoretical models, we used the color I-J, the J-band absolute magnitude, and the detection of the LiI 6708{AA} doublet line as a strong constraint to estimate masses and ages of our targets. For the search of debris disks, we observed three targets at submillimeter wavelength of 850um. We report here the first clear detections of lithium absorption in four targets and a marginal detection in one target. Our mass estimates indicate that two of them are young brown dwarfs, two are young brown dwarf candidates, and one is a young very low-mass star. The closest young field brown dwarf in our sample at only ~15pc is an excellent benchmark for further studying physical properties of brown dwarfs in the range 100-150Myr. We did not detect any debris disks around three late-M dwarfs, and we estimated upper limits to the dust mass of debris disks around them.
1607. Spectra of NGC 1333 Class I-Class II stars
ID:
ivo://CDS.VizieR/J/A+A/650/A43
Title:
Spectra of NGC 1333 Class I-Class II stars
Short Name:
J/A+A/650/A43
Date:
21 Oct 2021
Publisher:
CDS
Description:
The mass accretion rate (dM/dt_acc_) is the fundamental parameter to understand the process of mass assembly that results in the formation of a low-mass star. This parameter has been largely studied in Classical T Tauri stars in star-forming regions with ages of ~1-10Myr. However, little is known about the accretion properties of young stellar objects (YSOs) in younger regions and early stages of star formation, such as in the Class 0/I phases. We present new near-infrared spectra of 17 Class I/Flat and 35 Class II sources located in the young (<1Myr) NGC 1333 cluster, acquired with the KMOS instrument at the Very Large Telescope. Our goal is to study whether the mass accretion rate evolves with age, as suggested by the widely adopted viscous evolution model, by comparing the properties of the NGC 1333 members with samples of older regions. For the Class II sources in our sample, we measured the stellar parameters (SpT, AV, and L*) through a comparison of the IR spectra with a grid of non-accreting Class III stellar templates. We then computed the accretion luminosity by using the known correlation between Lacc and the luminosity of HI lines (Pa{beta} and Br{gamma}). For the Class I sample, where the presence of a large IR excess makes it impossible to use the same spectral typing method, we applied a procedure that allowed us to measure the stellar and accretion luminosity in a self-consistent way. Mass accretion rates dM/dt_acc_ were then measured once masses and radii were estimated adopting suitable evolutionary tracks. The NGC 1333 Class II sources of our sample have L_acc_~10^-4^-1L_{sun}_ and dM/dt_acc_~10^-11^-10^-7^M_{sun}_/yr. We find a correlation between accretion and stellar luminosity in the form of log L_acc_=(1.5+/-0.2)logL*+(-1.0+/-0.1), and a correlation between the mass accretion rate and stellar mass in the form of log(dM/dt_acc_)=(2.6+/-0.9)logM*+(-7.3+/-0.7). Both correlations are compatible within the errors with the older Lupus star-forming region, while only the latter is consistent with results from Chamaeleon I. The Class I sample shows larger accretion luminosities (~10^-2^-10^2^L_{sun}_) and mass accretion rates (~10^-9^-10^-6^M_{sun}_/yr) with respect to the Class II stars of the same cloud. However, the derived mass accretion rates are not sufficiently high to build up the inferred stellar masses, assuming steady accretion during the Class I lifetime. This suggests that the sources are not in their main accretion phase and that most of their mass has already been accumulated during a previous stage and/or that the accretion is an episodic phenomenon. We show that some of the targets originally classified as Class I through Spitzer photometry are in fact evolved or low accreting objects. This evidence can have implications for the estimated protostellar phase lifetimes. The accretion rates of our sample are larger in more embedded and early stage YSOs. Further observations of larger samples in young star-forming regions are needed to determine if this is a general result. In addition, we highlight the importance of spectroscopic surveys of YSOs to confirm their classification and perform a more correct estimate of their lifetime.
1608. Spectra of normal stars in the J-band
ID:
ivo://CDS.VizieR/J/ApJ/535/325
Title:
Spectra of normal stars in the J-band
Short Name:
J/ApJ/535/325
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a catalog of J-band spectra for 88 fundamental MK standard stars observed at a resolving power of R~3000. This contribution serves as a companion atlas to the K-band spectra recently published by Wallace & Hinkle (1997, Cat. <J/ApJS/111/445>) and the H-band atlas by Meyer and coworkers. We report data from 7400 to 9550cm^-1^ (1.05-1.34um) for stars of spectral types O7-M6 and luminosity classes I-V as defined in the MK system. In reducing these data, special care has been taken to remove time-variable telluric features of water vapor. We identify atomic and molecular indexes that are both temperature and luminosity sensitive that aid in the classification of stellar spectra in the J band. In addition to being useful in the classification of late-type stars, the J band contains several features of interest in the study of early-type stellar photospheres.
1609. Spectra of normal stars in the K band
ID:
ivo://CDS.VizieR/J/ApJS/111/445
Title:
Spectra of normal stars in the K band
Short Name:
J/ApJS/111/445
Date:
21 Oct 2021
Publisher:
CDS
Description:
An Atlas of 115 medium-resolution K-band (2.0-2.4um) stellar spectra, spanning spectral types O-M and luminosity types I-V, is presented. K-band spectra are also presented for one N- and one J-type carbon star. A time series of spectra is presented for an S-type Mira variable. All the spectra are at a resolution of ~3000 (1.4cm^-1^) and have had the terrestrial absorption removed by dividing a featureless spectrum. The spectra are plotted with the major spectral features identified and are available digitally.
1610. Spectra of normal stars in the L-band
ID:
ivo://CDS.VizieR/J/AJ/124/3393
Title:
Spectra of normal stars in the L-band
Short Name:
J/AJ/124/3393
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a brief atlas of L-band (3.3-4.2um) spectra for 42 stars plus the Sun and a sunspot observed at a resolving power of R~3000. This contribution is intended to supplement our previous K-band, H-band, and J-band spectral atlases. The L-band data, which cover some or all of the 2400 to 3000cm^-1^ (3.3-4.2um) region, are mainly for luminous late-type stars. In reducing these data, special care has been taken to remove telluric features, especially water vapor. We identify temperature- and luminosity-sensitive atomic and molecular indices to aid in the classification of stellar spectra in the L band.