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1101. Hot degenerates in the MCT survey. III.
ID:
ivo://CDS.VizieR/J/AJ/162/188
Title:
Hot degenerates in the MCT survey. III.
Short Name:
J/AJ/162/188
Date:
21 Mar 2022 00:13:43
Publisher:
CDS
Description:
We present optical spectra of 144 white dwarfs detected in the Montreal-Cambridge-Tololo colorimetric survey, including 120 DA, 12 DB, 4 DO, 1 DQ, and 7 DC stars. We also perform a model atmosphere analysis of all objects in our sample using the so-called spectroscopic technique, or the photometric technique in the case of DC white dwarfs. The main objective of this paper is to contribute to the ongoing effort of confirming spectroscopically all white dwarf candidates in the Gaia survey, in particular in the southern hemisphere. All our spectra are made available in the Montreal White Dwarf Database.
1102. Hot methane (CH4) line list
ID:
ivo://CDS.VizieR/J/ApJ/757/46
Title:
Hot methane (CH4) line list
Short Name:
J/ApJ/757/46
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present comprehensive experimental line lists of methane (CH_4_) at high temperatures obtained by recording Fourier transform infrared emission spectra. Calibrated line lists are presented for the temperatures 300-1400{deg}C at twelve 100{deg}C intervals spanning the 960-5000/cm (2.0-10.4{mu}m) region of the infrared. This range encompasses the dyad, pentad, and octad regions, i.e., all fundamental vibrational modes along with a number of combination, overtone and hot bands. Using our CH_4_ spectra, we have estimated empirical lower state energies (E_low_ in cm^-1^) and our values have been incorporated into the line lists along with line positions ({nu} in cm^-1^) and calibrated line intensities (S' in cm/molecule). We expect our hot CH_4_ line lists to find direct application in the modeling of planetary atmospheres and brown dwarfs.
1103. Hot stars in LMC UKST H{alpha} survey
ID:
ivo://CDS.VizieR/J/MNRAS/425/355
Title:
Hot stars in LMC UKST H{alpha} survey
Short Name:
J/MNRAS/425/355
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present new, accurate positions, spectral classifications, radial and rotational velocities, H{alpha} fluxes, equivalent widths and B, V, I, R magnitudes for 579 hot emission-line stars (classes B0-F9) in the Large Magellanic Cloud (LMC) which include 469 new discoveries. Candidate emission-line stars were discovered using a deep, high-resolution H{alpha} map of the central 25 degree^2^ of the LMC obtained by median stacking a dozen 2h H{alpha} exposures taken with the UK Schmidt Telescope (UKST). Spectroscopic follow-up observations on the Anglo-Australian Telescope, the UKST, the Very Large Telescope, the South African Astronomical Observatory 1.9m and the 2.3-m telescope at Siding Spring Observatory have established the identity of these faint sources down to magnitude R_equiv_~23 for H{alpha} (4.5x10^-17^ergs/cm^2^/s/{AA}).
1104. Hot subdwarf stars in LAMOST DR1
ID:
ivo://CDS.VizieR/J/ApJ/818/202
Title:
Hot subdwarf stars in LAMOST DR1
Short Name:
J/ApJ/818/202
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a catalog of 166 spectroscopically identified hot subdwarf stars from LAMOST DR1, 44 of which show the characteristics of cool companions in their optical spectra. Atmospheric parameters of 122 subdwarf stars with non-composite spectra were measured by fitting the profiles of hydrogen (H) and helium (He) lines with synthetic spectra from non-LTE model atmospheres. A unique property of our sample is that it covers a large range in apparent magnitude and galactic latitude, therefore it contains a mix of stars from different populations and galactic environments.
1105. How to constrain your M dwarf. II. Nearby binaries
ID:
ivo://CDS.VizieR/J/ApJ/871/63
Title:
How to constrain your M dwarf. II. Nearby binaries
Short Name:
J/ApJ/871/63
Date:
21 Oct 2021
Publisher:
CDS
Description:
The mass-luminosity relation for late-type stars has long been a critical tool for estimating stellar masses. However, there is growing need for both a higher-precision relation and a better understanding of systematic effects (e.g., metallicity). Here we present an empirical relationship between M_Ks_ and M_*_ spanning 0.075M_{sun}_<M_*_<0.70M_{sun}_. The relation is derived from 62 nearby binaries, whose orbits we determine using a combination of near infra-red (Keck/NIRC2) imaging, archival adaptive optics data, and literature astrometry. From their orbital parameters, we determine the total mass of each system, with a precision better than 1% in the best cases. We use these total masses, in combination with resolved Ks magnitudes and system parallaxes, to calibrate the M_Ks_-M_*_ relation. The resulting posteriors can be used to determine masses of single stars with a precision of 2%-3%, which we confirm by testing the relation on stars with individual dynamical masses from the literature. The precision is limited by scatter around the best-fit relation beyond measured M_*_ uncertainties, perhaps driven by intrinsic variation in the M_Ks_-M_*_ relation or underestimated uncertainties in the input parallaxes. We find that the effect of [Fe/H] on the M_Ks_-M_*_ relation is likely negligible for metallicities in the solar neighborhood (0.0%{+/-}2.2% change in mass per dex change in [Fe/H]). This weak effect is consistent with predictions from the Dartmouth Stellar Evolution Database, but inconsistent with those from modules for experiments in stellar astrophysics (MESA) Isochrones and Stellar Tracks (MIST) (at 5{sigma}). A sample of binaries with a wider range of abundances will be required to discern the importance of metallicity in extreme populations (e.g., in the Galactic halo or thick disk).
1106. HPF RVs and TESS photometry of TOI-1266
ID:
ivo://CDS.VizieR/J/AJ/160/259
Title:
HPF RVs and TESS photometry of TOI-1266
Short Name:
J/AJ/160/259
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report on the validation of two planets orbiting the nearby (36pc) M2 dwarf TOI-1266 observed by the TESS mission. This system is one of a few M dwarf multiplanet systems with close-in planets where the inner planet is substantially larger than the outer planet. The inner planet is sub-Neptune-sized (R=2.46{+/-}0.08R{Earth}) with an orbital period of 10.9days, while the outer planet has a radius of 1.67_-0.11_^+0.09^R{Earth} and resides in the exoplanet radius valley-the transition region between rocky and gaseous planets. With an orbital period of 18.8days, the outer planet receives an insolation flux of 2.4 times that of Earth, similar to the insolation of Venus. Using precision near-infrared radial velocities with the Habitable-zone Planet Finder Spectrograph, we place upper mass limits of 15.9 and 6.4M{Earth} at 95% confidence for the inner and outer planet, respectively. A more precise mass constraint of both planets, achievable with current radial velocity instruments given the host star brightness (V=12.9, J=9.7), will yield further insights into the dominant processes sculpting the exoplanet radius valley.
1107. HR 8799e and HR 8799d spectra
ID:
ivo://CDS.VizieR/J/A+A/587/A57
Title:
HR 8799e and HR 8799d spectra
Short Name:
J/A+A/587/A57
Date:
21 Oct 2021
Publisher:
CDS
Description:
The planetary system discovered around the young A-type HR 8799 provides a unique laboratory to: a) test planet formation theories; b) probe the diversity of system architectures at these separations, and c) perform comparative (exo)planetology. We present and exploit new near-infrared images and integral-field spectra of the four gas giants surrounding HR 8799 obtained with SPHERE, the new planet finder instrument at the Very Large Telescope, during the commissioning and science verification phase of the instrument (July-December 2014). With these new data, we contribute to completing the spectral energy distribution (SED) of these bodies in the 1.0-2.5um range. We also provide new astrometric data, in particular for planet e, to further constrain the orbits. We used the infrared dual-band imager and spectrograph (IRDIS) subsystem to obtain pupil-stabilized, dual-band H2H3 (1.593um, 1.667um), K1K2 (2.110um, 2.251um), and broadband J (1.245um) images of the four planets. IRDIS was operated in parallel with the integral field spectrograph (IFS) of SPHERE to collect low-resolution (R~30), near-infrared (0.94-1.64um) spectra of the two innermost planets HR 8799 d and e. The data were reduced with dedicated algorithms, such as the Karhunen-Loeve image projection (KLIP), to reveal the planets. We used the so-called negative planets injection technique to extract their photometry, spectra, and measure their positions. We illustrate the astrometric performance of SPHERE through sample orbital fits compatible with SPHERE and literature data.
1108. HR8799e K-band spectrum
ID:
ivo://CDS.VizieR/J/A+A/623/L11
Title:
HR8799e K-band spectrum
Short Name:
J/A+A/623/L11
Date:
22 Feb 2022
Publisher:
CDS
Description:
To date, infrared interferometry at best achieved contrast ratios of a few times 10^-4^ on bright targets. GRAVITY, with its dual-field mode, is now capable of high contrast observations, enabling the direct observation of exoplanets. We demonstrate the technique on HR 8799, a young planetary system composed of four known giant exoplanets. We used the GRAVITY fringe tracker to lock the fringes on the central star, and integrated off-axis on the HR 8799 e planet situated at 390mas from the star. Data reduction included post-processing to remove the flux leaking from the central star and to extract the coherent flux of the planet. The inferred K band spectrum of the planet has a spectral resolution of 500. We also derive the astrometric position of the planet relative to the star with a precision on the order of 100{mu}as. The GRAVITY astrometric measurement disfavors perfectly coplanar stable orbital solutions. A small adjustment of a few degrees to the orbital inclination of HR 8799 e can resolve the tension, implying that the orbits are close to, but not strictly coplanar. The spectrum, with a signal-to-noise ratio of ~5 per spectral channel, is compatible with a late-type L brown dwarf. Using Exo-REM synthetic spectra, we derive a temperature of 1150+/-50K and a surface gravity of 10^4.3+/-0.3^cm.s^2^. This corresponds to a radius of 1.17_-0.11_^+0.13^R_Jup_ and a mass of 10_-4_^+7^M_Jup_, which is an independent confirmation of mass estimates from evolutionary models. Our results demonstrate the power of interferometry for the direct detection and spectroscopic study of exoplanets at close angular separations from their stars.
1109. 1H 0323+342 rest frame optical spectrum with GHAO
ID:
ivo://CDS.VizieR/J/ApJ/795/58
Title:
1H 0323+342 rest frame optical spectrum with GHAO
Short Name:
J/ApJ/795/58
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present optical and near-infrared (NIR) imaging data of the radio-loud, narrow-line Seyfert 1 galaxy 1H 0323+342, which shows intense and variable gamma-ray activity discovered by the Fermi satellite with the Large Area Telescope. Near-infrared and optical images are used to investigate the structural properties of the host galaxy of 1H 0323+342; this together with optical spectroscopy allows us to examine its black hole mass. Based on two-dimensional (2D) multiwavelength surface-brightness modeling, we find that statistically, the best model fit is a combination of a nuclear component and a Sersic profile (n~2.8). However, the presence of a disk component (with a small bulge n~1.2) also remains a possibility and cannot be ruled out with the present data. Although at first glance a spiral-arm-like structure is revealed in our images, a 2D Fourier analysis of the imagery suggests that this structure corresponds to an asymmetric ring, likely associated with a recent violent dynamical interaction. We discuss our results in the context of relativistic jet production and galaxy evolution.
1110. HR 8257: orbit and basic properties
ID:
ivo://CDS.VizieR/J/ApJ/695/1527
Title:
HR 8257: orbit and basic properties
Short Name:
J/ApJ/695/1527
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have used interferometric and spectroscopic observations of HR 8257 to determine a three-dimensional orbit of the system. The orbit has a period of 12.21345 days and an eccentricity of 0.2895. The masses of the F0 and F2 dwarf components are 1.56 and 1.38M_{sun}_, respectively, with fractional errors of 1.4%. Our orbital parallax of 13.632+/-0.095mas, corresponding to a distance of 73.4+/-0.6pc, differs from the Hipparcos result by just 2% and has a significantly smaller uncertainty. From our spectroscopic observations and spectral energy distribution modeling we determine the component effective temperatures and luminosities to be T_eff_(A)=7030+/-200K and T_eff_(B)=6560+/-200K and L_A_=9.4+/-0.3L_{sun}_ and L_B_=4.7+/-0.2L_{sun}_. The primary rotates pseudosynchronously, while the secondary is not far from its pseudosynchronous rotational velocity. Although both early-F stars are slowly rotating, neither component of this close binary is an Am star. A comparison with evolutionary tracks indicates that the stars are slightly metal poor, and although the components have evolved away from the zero-age main sequence, they are both still dwarfs.

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