- ID:
- ivo://CDS.VizieR/J/ApJS/143/513
- Title:
- Spectral classification of close binaries
- Short Name:
- J/ApJS/143/513
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A sample of 135 stars with composite spectra has been observed in the near-UV spectral region with the Aurelie spectrograph at the Observatoire de Haute-Provence. Using the spectral classifications of the cool components previously determined with near infrared spectra, we obtained reliable spectral types of the hot components of the sample systems. The hot components were isolated by the subtraction method using MK standards as surrogates of the cool components. We also derived the visual magnitude differences between the components using Willstrop's normalized stellar flux ratios. We propose a photometric model for each of these systems on the basis of our spectroscopic data and the Hipparcos data.
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- ID:
- ivo://CDS.VizieR/J/A+A/624/A49
- Title:
- Spectra of Earth-like planets around M-dwarfs
- Short Name:
- J/A+A/624/A49
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The characterisation of the atmosphere of exoplanets is one of the main goals of exoplanet science in the coming decades. We investigate the detectability of atmospheric spectral features of Earth-like planets in the habitable zone (HZ) around M dwarfs with the future James Webb Space Telescope (JWST). We used a coupled 1D climate-chemistry-model to simulate the influence of a range of observed and modelled M-dwarf spectra on Earth-like planets. The simulated atmospheres served as input for the calculation of the transmission spectra of the hypothetical planets, using a line-by-line spectral radiative transfer model. To investigate the spectroscopic detectability of absorption bands with JWST we further developed a signal- to-noise ratio (S/N) model and applied it to our transmission spectra. High abundances of methane (CH_4_) and water (H_2_O) in the atmosphere of Earth-like planets around mid to late M dwarfs increase the detectability of the corresponding spectral features compared to early M-dwarf planets. Increased temperatures in the middle atmosphere of mid- to late-type M-dwarf planets expand the atmosphere and further increase the detectability of absorption bands. To detect CH_4_, H_2_O, and carbon dioxide (CO_2_) in the atmosphere of an Earth-like planet around a mid to late M dwarf observing only one transit with JWST could be enough up to a distance of 4pc and less than ten transits up to a distance of 10pc. As a consequence of saturation limits of JWST and less pronounced absorption bands, the detection of spectral features of hypothetical Earth-like planets around most early M dwarfs would require more than ten transits. We identify 276 existing M dwarfs (including GJ 1132, TRAPPIST-1, GJ 1214, and LHS 1140) around which atmospheric absorption features of hypothetical Earth-like planets could be detected by co-adding just a few transits. The TESS satellite will likely find new transiting terrestrial planets within 15pc from the Earth. We show that using transmission spectroscopy, JWST could provide enough precision to be able to partly characterise the atmosphere of TESS findings with an Earth-like composition around mid to late M dwarfs.
1113. Spectra of 12 ON stars
- ID:
- ivo://CDS.VizieR/J/A+A/578/A109
- Title:
- Spectra of 12 ON stars
- Short Name:
- J/A+A/578/A109
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Massive stars burn hydrogen through the CNO cycle during most of their evolution. When mixing is efficient or when mass transfer in binary systems occurs, chemically processed material is observed at the surface of O and B stars. ON stars show stronger lines of nitrogen than morphologically normal counterparts. Whether this corresponds to the presence of material processed through the CNO cycle is not known. Our goal is to answer this question. We performed a spectroscopic analysis of a sample of ON stars with atmosphere models. We determined the fundamental parameters as well as the He, C, N, and O surface abundances. We also measured the projected rotational velocities. We compared the properties of the ON stars to those of normal O stars.
- ID:
- ivo://CDS.VizieR/J/A+A/327/191
- Title:
- Spectrophotometry of southern symbiotic stars
- Short Name:
- J/A+A/327/191
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have analyzed the optical spectra of 67 symbiotic stars and objects suspected of being symbiotic, and found 18 new symbiotic systems. This is the largest homogeneous set of optical spectrophotometric data for symbiotic binaries ever studied. We have derived the reddenings and distances for all systems, estimated the IR classes (S and D) for the new systems, and determined the location of the hot components in the Hertzsprung-Russell diagram.
- ID:
- ivo://CDS.VizieR/J/ApJ/691/1145
- Title:
- Spectrophotometry of TrES-3 and TrES-4
- Short Name:
- J/ApJ/691/1145
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report new spectroscopic and photometric observations of the parent stars of the recently discovered transiting planets TrES-3 and TrES-4. A detailed abundance analysis based on high-resolution spectra yields [Fe/H]=-0.19+/-0.08, Teff=5650+/-75K, and logg=4.4+/-0.1 for TrES-3, and [Fe/H]=+0.14+/-0.09, Teff=6200+/-75K, and logg=4.0+/-0.1 for TrES-4. The accuracy of the effective temperatures is supported by a number of independent consistency checks. The spectroscopic orbital solution for TrES-3 is improved with our new radial velocity measurements of that system, as are the light-curve parameters for both systems based on newly acquired photometry for TrES-3 and a reanalysis of existing photometry for TrES-4. With these revised stellar parameters, we obtain improved values for the planetary masses and radii. We find M_p_=1.910^+0.075^_-0.080_M_Jup_, R_p_=1.336^+0.031^_-0.036_R_Jup_ for TrES-3, and M_p_=0.925+/-0.082M_Jup_, R_p_=1.783^+0.093^_-0.086_R_Jup_ for TrES-4. We confirm TrES-4 as the planet with the largest radius among the currently known transiting hot Jupiters.
- ID:
- ivo://CDS.VizieR/J/ApJ/770/43
- Title:
- Spectroscopic [Fe/H] of Kepler stars
- Short Name:
- J/ApJ/770/43
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- It has been shown that F, G, and early K dwarf hosts of Neptune-sized planets are not preferentially metal-rich. However, it is less clear whether the same holds for late K and M dwarf planet hosts. We report metallicities of Kepler targets and candidate transiting planet hosts with effective temperatures below 4500K. We use new metallicity calibrations to determine [Fe/H] from visible and near-infrared spectra. We find that the metallicity distribution of late K and M dwarfs monitored by Kepler is consistent with that of the solar neighborhood. Further, we show that hosts of Earth- to Neptune-sized planets have metallicities consistent with those lacking detected planets and rule out a previously claimed 0.2dex offset between the two distributions at 6{sigma} confidence. We also demonstrate that the metallicities of late K and M dwarfs hosting multiple detected planets are consistent with those lacking detected planets. Our results indicate that multiple terrestrial and Neptune-sized planets can form around late K and M dwarfs with metallicities as low as 0.25 solar. The presence of Neptune-sized planets orbiting such low-metallicity M dwarfs suggests that accreting planets collect most or all of the solids from the disk and that the potential cores of giant planets can readily form around M dwarfs. The paucity of giant planets around M dwarfs compared to solar-type stars must be due to relatively rapid disk evaporation or a slower rate of planet accretion, rather than insufficient solids to form a core.
- ID:
- ivo://CDS.VizieR/J/A+A/487/373
- Title:
- Spectroscopic parameters of 451 HARPS-GTO stars
- Short Name:
- J/A+A/487/373
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- To understand the formation and evolution of solar-type stars in the solar neighborhood, we need to measure their stellar parameters to high accuracy. We present a catalogue of accurate stellar parameters for 451 stars that represent the HARPS Guaranteed Time Observations (GTO) "high precision" sample. Spectroscopic stellar parameters were measured using high signal-to-noise (S/N) spectra acquired with the HARPS spectrograph. The spectroscopic analysis was completed assuming LTE with a grid of Kurucz atmosphere models and the recent ARES code for measuring line equivalent widths. We show that our results agree well with those ones presented in the literature (for stars in common). We present a useful calibration for the effective temperature as a function of the index color B-V and [Fe/H]. We use our results to study the metallicity-planet correlation, namely for very low mass planets. The results presented here suggest that in contrast to their jovian counterparts, Neptune-like planets do not form preferentially around metal-rich stars. The ratio of Jupiter-to-Neptune is also an increasing function of stellar metallicity. These results are discussed in the context of the core-accretion model for planet formation.
- ID:
- ivo://CDS.VizieR/J/ApJ/652/681
- Title:
- Spectroscopic subcomponents in multiple systems
- Short Name:
- J/ApJ/652/681
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We propose a methodology for analyzing triple stellar systems that include a visual double star wherein one of the components is a single- or double-lined spectroscopic binary. By using this methodology, we can calculate the most probable values of the spectroscopic binary's inclination, the angular separation between its components, and its stellar masses, and we can even estimate the spectral types. For a few W UMa-type eclipsing binaries, stellar radii are also determined. Moreover, we present new formulae for calculating stellar masses depending on spectral type. In this way we have studied 61 triple systems, five of them W UMatype eclipsing binaries with low-mass subcomponents. In addition, we study nine quadruple systems, applying the same methodology and considering them twice as a triple system.
- ID:
- ivo://CDS.VizieR/J/A+A/382/118
- Title:
- Spectroscopic sub-systems in multiple stars
- Short Name:
- J/A+A/382/118
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A large sample of visual multiples of spectral types F5-M has been surveyed for the presence of spectroscopic sub-systems. In table 1 we provide basic identifiers for the components or their combinations, average radial velocities, parameters of correlation dips and analysis of the velocity variability and physical relation. Notes contain comments and additional identifiers. Individual radial velocities yet unpublished are listed in table 2. Table 6 is extracted from the Multiple Star Catalog (Cat. <J/A+AS/124/75>) for the analysis of the statistics of spectroscopic+visual multiple stellar systems.
- ID:
- ivo://CDS.VizieR/J/AJ/148/29
- Title:
- Spectroscopy and differential photometry of HATS-4
- Short Name:
- J/AJ/148/29
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the discovery by the HATSouth survey of HATS-4b, an extrasolar planet transiting a V=13.46mag G star. HATS-4b has a period of P{approx}2.5167days, mass of M_p_{approx}1.32M_Jup_, radius of R_p_{approx}1.02R_Jup_, and density of {rho}_p_=1.55+/-0.16g/cm3{approx}1.24{rho}_Jup_. The host star has a mass of 1.00 M_{sun}_, a radius of 0.92 R_{sun}_, and a very high metallicity [Fe/H]=0.43+/-0.08. HATS-4b is among the densest known planets with masses between 1 and 2M_J_ and is thus likely to have a significant content of heavy elements of the order of 75M_{oplus}_. In this paper we present the data reduction, radial velocity measurements, and stellar classification techniques adopted by the HATSouth survey for the CORALIE spectrograph. We also detail a technique for simultaneously estimating vsini and macroturbulence using high resolution spectra.
