- ID:
- ivo://CDS.VizieR/J/AJ/160/104
- Title:
- {Epsilon} CrA components radial & orbital velocity
- Short Name:
- J/AJ/160/104
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- High-resolution spectroscopic observations of the W UMa-type binary {Epsilon}CrA obtained as a time-monitoring sequence on four full and four partial nights within two weeks have been used to derive orbital elements of the system and discuss the validity of the Lucy model for description of the radial-velocity data. The observations had more extensive temporal coverage and better quality than similar time-sequence observations of the contact binary AW UMa. The two binaries share several physical properties and show very similar deviations from the Lucy model: the primary component is a rapidly rotating star almost unaffected by the presence of the secondary component, while the latter is embedded in a complex gas flow and appears to have its own rotation-velocity field, in contradiction to the model. The spectroscopic mass ratio is found to be larger than the one derived from the light-curve analysis, as in many other W UMa-type binaries, but the discrepancy for {Epsilon} CrA is relatively minor, much smaller than for AW UMa. The presence of the complex velocity flows contradicting the assumption of solid-body rotation suggests a necessity of modification to the Lucy model, possibly along the lines outlined by Stepien in his concept of energy transfer between the binary components.
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- ID:
- ivo://CDS.VizieR/J/A+A/510/A99
- Title:
- Epsilon Indi Ba and Bb IR spectra
- Short Name:
- J/A+A/510/A99
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The discovery of epsilon Indi Ba, Bb, a binary brown dwarf system very close to the Sun, makes possible a concerted campaign to characterise the physical parameters of two T dwarfs. Recent observations suggest substellar atmospheric and evolutionary models may be inconsistent with observations, but there have been few conclusive tests to date. We therefore aim to characterise these benchmark brown dwarfs to place constraints on such models. We have obtained high angular resolution optical, near-infrared, and thermal-infrared imaging and medium-resolution (up to R~5000) spectroscopy of epsilon Indi Ba, Bb with the ESO VLT and present VRIzJHKL'M' broad-band photometry and 0.63-5.1 micron spectroscopy of the individual components. The photometry and spectroscopy of the two partially blended sources were extracted with a custom algorithm. Furthermore, we use deep AO-imaging to place upper limits on the (model-dependent) mass of any further system members. We derive luminosities of log L/L_{sun}=-4.699+/-0.017 and -5.232+/-0.020 for epsilon Indi Ba, Bb, respectively, and using the dynamical system mass and COND03 evolutionary models predict a system age of 3.7-4.3Gyr, in excess of previous estimates and recent predictions from observations of these brown dwarfs. Moreover, the effective temperatures of 1352-1385K and 976-1011K predicted from the COND03 evolutionary models, for epsilon Indi Ba and Bb respectively, are in disagreement with those derived from the comparison of our data with the BT-Settl atmospheric models where we find effective temperatures of 1300-1340K and 880-940K, for epsilon Indi Ba and Bb respectively, with surface gravities of logg=5.25 and 5.50. Finally, we show that spectroscopically determined effective temperatures and surface gravities for ultra-cool dwarfs can lead to underestimated masses even where precise luminosity constraints are available.
- ID:
- ivo://CDS.VizieR/J/A+A/622/A190
- Title:
- eps Tau intensity and RV time-series data
- Short Name:
- J/A+A/622/A190
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Asteroseismic analysis of solar-like stars allows us to determine physical parameters such as stellar mass, with a higher precision compared to most other methods. Even in a well-studied cluster such as the Hyades, the masses of the red giant stars are not well known, and previous mass estimates are based on model calculations (isochrones). The four known red giants in the Hyades are assumed to be clump (core-helium-burning) stars based on their positions in colour-magnitude diagrams, however asteroseismology offers an opportunity to test this assumption. Using asteroseismic techniques combined with other methods, we aim to derive physical parameters and the evolutionary stage for the planet hosting star epsilon Tau, which is one of the four red giants located in the Hyades. We analysed time-series data from both ground and space to perform the asteroseismic analysis. By combining high signal-to-noise (S/N) radial-velocity data from the ground-based SONG network with continuous space-based data from the revised Kepler mission K2, we derive and characterize 27 individual oscillation modes for epsilon Tau, along with global oscillation parameters such as the large frequency separation {Delta}{nu} and the ratio between the amplitude of the oscillations measured in radial velocity and intensity as a function of frequency. The latter has been measured previously for only two stars, the Sun and Procyon. Combining the seismic analysis with interferometric and spectroscopic measurements, we derive physical parameters for epsilon Tau, and discuss its evolutionary status. Along with other physical parameters, we derive an asteroseismic mass for epsilon Tau of M=2.458+/-0.073M_{sun}_, which is slightly lower than previous estimates, and which leads to a revised minimum mass of the planetary companion. Noting that the SONG and K2 data are non-simultaneous, we estimate the amplitude ratio between intensity and radial velocity to be 42.2+/-2.3ppm m/s, which is higher than expected from scaling relations.
- ID:
- ivo://CDS.VizieR/J/ApJ/416/276
- Title:
- Eq. of State in Magnetic Neutron Stars
- Short Name:
- J/ApJ/416/276
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This catalog is based on the calculated equation of state in cold dense matter. Each table in the catalog lists bulk properties of Fe-56 in a magnetic field ranging from one million to 1000 million Tesla.
- ID:
- ivo://CDS.VizieR/J/A+A/550/A43
- Title:
- Equation of state for magnetized plasmas
- Short Name:
- J/A+A/550/A43
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have developed an analytical equation of state (EOS) for magnetized fully-ionized plasmas that cover a wide range of temperatures and densities, from low-density classical plasmas to relativistic, quantum plasma conditions. This EOS directly applies to calculations of structure and evolution of strongly magnetized white dwarfs and neutron stars. We review available analytical and numerical results for thermodynamic functions of the nonmagnetized and magnetized Coulomb gases, liquids, and solids. We propose a new analytical expression for the free energy of solid Coulomb mixtures. Based on recent numerical results, we have constructed analytical approximations for the thermodynamic functions of harmonic Coulomb crystals in quantizing magnetic fields. The analytical description ensures a consistent evaluation of all astrophysically important thermodynamic functions based on the first, second, and mixed derivatives of the free energy. Our numerical code for calculation of thermodynamic functions based on these approximations has been made publicly available. Using this code, we calculate and discuss the effects of electron screening and magnetic quantization on the position of the melting point in a range of densities and magnetic fields relevant to white dwarfs and outer envelopes of neutron stars. We consider also the thermal and mechanical structure of a magnetar envelope and argue that it can have a frozen surface which covers the liquid ocean above the solid crust.
- ID:
- ivo://CDS.VizieR/II/161
- Title:
- Equatorial Infrared Catalog
- Short Name:
- II/161
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- EIC (Equatorial Infrared Catalog) lists positions and other information for 7,220 infrared stars. Each star is described by a 175-byte print record. The fields within each star record are defined here. The catalog was prepared as a result of additional processing of USAF satellite data at 2.7 micrometers for sources within 10 degrees of the celestial equator. Every source has been observed on two or more days or on the same day at times 20 minutes apart. The catalog includes right ascension and declination (equinox B1950.0), flux densities and their standard deviations, galactic coordinates, spectral types, and cross identifications to the numbering systems of EIC-1, the SAO and AFGL catalogs, and the Durchmusterung catalogs.
- ID:
- ivo://CDS.VizieR/J/AZh/79/249
- Title:
- Equatorial spectrophotometric standards
- Short Name:
- J/AZh/79/249
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Spectral energy distributions for 41 stars, 7-8mag, near the celestial equator (DE=+/-3{deg}) were obtained. The 3100-7600{AA} spectral range is studied with a spectral resolution of 50{AA}.
- ID:
- ivo://CDS.VizieR/III/139A
- Title:
- Equivalent Width Measures
- Short Name:
- III/139A
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The files in this data set contain equivalent width measures made in the course of a number of published studies for four types of objects: mid-to-late supergiants, metal-deficient red giants, subgiant CH stars, and G/K giants. The files include identified atomic and ionic species, wavelength, lower excitation potentials and log(gf) values. Subgiant CH stars in the data are late F to early G stars whose spectra exhibit strong CH, Sr II, and sometimes Ba II features.
- ID:
- ivo://CDS.VizieR/J/ApJ/711/1236
- Title:
- Equivalent width of H_2_ from FUSE
- Short Name:
- J/ApJ/711/1236
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Far Ultraviolet Spectroscopic Explorer (FUSE) has allowed precise determinations of the column densities of molecular hydrogen (H_2_) in Galactic lines of sight with a wide range of pathlengths and extinction properties. However, survey studies of lines of sight with greater extinction have been mostly restricted to the low-J states (lower total angular momentum) in which most molecular hydrogen is observed. This paper presents a survey of column densities for the molecular hydrogen in states of greater rotational excitation (J>=2) in Galactic lines of sight with log N(H_2_)>~20. This study is comprehensive through the highest excited state detectable in each line of sight. J=5 is observed in every line of sight, and we detect J=7 in four lines of sight, J=8 in one line of sight, and vibrationally excited H_2_ in two lines of sight.
- ID:
- ivo://CDS.VizieR/J/AJ/132/85
- Title:
- Equivalent width of 33 metal-poor RHB
- Short Name:
- J/AJ/132/85
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have conducted spectrum analyses of 24 field metal-poor ([Fe/H]<-2) red horizontal-branch (RHB) stars identified in the HK objective-prism survey and 6 such stars in the globular cluster M15, based on high-quality spectra (R~40000, S/N~100) obtained with the Magellan Inamori Kyocera Echelle spectrograph at the Clay 6.5m telescope at Las Campanas Observatory. The atmospheric parameters of the RHB stars provide interesting bridges between turnoff stars of similar temperature and red giant branch (RGB) stars of similar gravity, and they permit investigations of abundance trends [X/Fe] versus [Fe/H] in a relatively unexplored region of the temperature-gravity plane. We find that the Teff, logg, vt, and [Fe/H] values determined from our spectra are consistent with expectations from literature spectroscopic studies of other evolved metal-poor stellar classes.