- ID:
- ivo://CDS.VizieR/J/A+A/597/A137
- Title:
- HD 123999 and Alpha Cen A and B OIFITS files
- Short Name:
- J/A+A/597/A137
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The photospheric radius is one of the fundamental parameters governing the radiative equilibrium of a star. We report new observations of the nearest solar-type stars Alpha Centauri A (G2V) and B (K1V) with the VLTI/PIONIER optical interferometer. The combination of four configurations of the VLTI enable us to measure simultaneously the limb darkened angular diameter thetaLD and the limb darkening parameters of the two solar-type stars in the near-infrared H band (lambda=1.65um). We obtain photospheric angular diameters of {theta}_LD(A)_=8.502+/-0.038mas (0.43%) and {theta}_LD(B)_=5.999+/-0.025mas (0.42%), through the adjustment of a power law limb darkening model. We find H band power law exponents of {alpha}_(A)_=0.1404+/-0.0050 (3.6%) and {alpha}_(B)_=0.1545+/-0.0044 (2.8%), which closely bracket the observed solar value (alpha_{sun}_=0.15027). Combined with the parallax pi=747.17+/-0.61mas determined by Kervella et al. (2016), we derive linear radii of R_A_=1.2234+/-0.0053R_{sun}_ (0.43%) and R_B_=0.8632+/-0.0037R_{sun}_ (0.43%). The power law exponents that we derive for the two stars indicate a significantly weaker limb darkening than predicted by both 1D and 3D stellar atmosphere models. As this discrepancy is also observed on the near-infrared limb darkening profile of the Sun, an improvement of the calibration of stellar atmosphere models is clearly needed. The reported PIONIER visibility measurements of Alpha Cen A and B provide a robust basis to validate the future evolutions of these models.
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Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/417/495
- Title:
- HD 32115 and HD 37594 atmospheric parameters
- Short Name:
- J/MNRAS/417/495
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present detailed parameter determinations of two chemically normal late A-type stars, HD 32115 and HD 37594, to uncover the reasons behind large discrepancies between two previous analyses of these stars performed with a semi-automatic procedure and a 'classical' analysis. Our study is based on high-resolution, high signal-to-noise ratio spectra obtained at the McDonald Observatory. Our method is based on the simultaneous use of all available observables: multicolour photometry, pressure-sensitive magnesium lines, metallic lines and Balmer line profiles. Our final set of fundamental parameters fits, within the error bars, all available observables. It differs from the published results obtained with a semi-automatic procedure.
- ID:
- ivo://CDS.VizieR/J/ApJS/232/19
- Title:
- H_2_, D_2_, and HD c^3^{Pi}_u_^-^(v,N) levels
- Short Name:
- J/ApJS/232/19
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The c^3^{Pi}_u_ state of the hydrogen molecule has the second largest triplet-state excitation cross-section, and plays an important role in the heating of the upper thermospheres of outer planets by electron excitation. Precise energies of the H_2_, D_2_, and HD c^3^{Pi}_u_^-^(v,N) levels are calculated from highly accurate ab initio potential energy curves that include relativistic, radiative, and empirical non-adiabatic corrections. The emission yields are determined from predissociation rates and refined radiative transition probabilities. The excitation function and excitation cross-section of the c^3^{Pi}_u_ state are extracted from previous theoretical calculations and experimental measurements. The emission cross-section is determined from the calculated emission yield and the extracted excitation cross-section. The kinetic energy (Ek) distributions of H atoms produced via the predissociation of the c^3^{Pi}_u_ state, the c^3^{Pi}_u_^-^-b^3^{Sigma}_u_^+^ dissociative emission by the magnetic dipole and electric quadrupole, and the c^3^{Pi}_u_-a^3^{Sigma}_g_^+^-b^3^{Sigma}_u_^+^ cascade dissociative emission by the electric dipole are obtained. The predissociation of the c^3^{Pi}_u_^+^ and c^3^{Pi}_u_^-^ states both produce H(1s) atoms with an average Ek of ~4.1eV/atom, while the c^3^{Pi}_u_^-^-b^3^{Sigma}_u_^+^ dissociative emissions by the magnetic dipole and electric quadrupole give an average Ek of ~1.0 and ~0.8eV/atom, respectively. The c^3^{Pi}_u_-a^3^{Sigma}_g_^+^-b^3^{Sigma}_u_^+^ cascade and dissociative emission gives an average Ek of ~1.3 eV/atom. On average, each H_2_ excited to the c^3^{Pi}_u_ state in an H_2_-dominated atmosphere deposits ~7.1eV into the atmosphere while each H_2_ directly excited to the a^3^{Sigma}_g_^+^ and d^3^{Pi}_u_ states contribute ~2.3 and ~3.3eV, respectively, to the atmosphere. The spectral distribution of the calculated continuum emission arising from the X^1^{Sigma}_g_^+^-c^3^{Pi}_u_ excitation is significantly different from that of direct a^3^{Sigma}_g_^+^ or d^3^{Pi}_u_ excitations.
- ID:
- ivo://CDS.VizieR/J/A+A/539/A102
- Title:
- HD 209458 and HD 189733 theoretical spectra
- Short Name:
- J/A+A/539/A102
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We compare limb darkening laws derived from 3D hydrodynamical model atmospheres and 1D hydrostatic MARCS models for the host stars of two well-studied transiting exoplanet systems, the late-type dwarfs HD 209458 and HD 189733. The surface brightness distribution of the stellar disks is calculated for a wide spectral range using 3D LTE spectrum formation and opacity sampling. We test our theoretical predictions using least-squares fits of model light curves to wavelength-integrated primary eclipses that were observed with the Hubble Space Telescope (HST).
- ID:
- ivo://CDS.VizieR/J/A+A/511/A45
- Title:
- HD 147018, 171238 and 204313 radial velocities
- Short Name:
- J/A+A/511/A45
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the detection of a double planetary system around HD140718 as well as the discovery of two long period and massive planets orbiting HD171238 and HD204313. Those discoveries were made with the CORALIE Echelle spectrograph mounted on the 1.2-m Euler Swiss telescope located at La Silla Observatory, Chile. The planetary system orbiting the nearby G9 dwarf HD147018 is composed of an eccentric inner planet (e=0.47) with twice the mass of Jupiter (2.1M_Jup_) and with an orbital period of 44.24-days. The outer planet is even more massive (6.6M_Jup_) with a slightly eccentric orbit (e=0.13) and a period of 1008-days. The planet orbiting HD171238 has a minimum mass of 2.6M_Jup_, a period of 1523-days and an eccentricity of 0.40. It orbits a G8 dwarfs at 2.5AU. The last planet, HD204313 b, is a 4.0 M_Jup_-planet with a period of 5.3-years and has a low eccentricity (e=0.13). It orbits a G5 dwarfs at 3.1AU. The three parent stars are metal rich, which further strengthened the case that massive planets tend to form around metal rich stars.
- ID:
- ivo://CDS.VizieR/J/A+A/592/A83
- Title:
- HD 100546 and TW Hya model abundances
- Short Name:
- J/A+A/592/A83
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The composition of planetary solids and gases is largely rooted in the processing of volatile elements in protoplanetary disks. To shed light on the key processes, we carry out a comparative analysis of the gas-phase carbon abundance in two systems with a similar age and disk mass, but different central stars: HD 100546 and TW Hya. We combine our recent detections of C0 in these disks with observations of other carbon reservoirs (CO, C^+^, C_2_H) and gas-mass and warm-gas tracers (HD, O^0^), as well as spatially resolved ALMA observations and the spectral energy distribution. The disks are modelled with the DALI 2D physical-chemical code. Stellar abundances for HD 100546 are derived from archival spectra. Upper limits on HD emission from HD 100546 place an upper limit on the total disk mass of <=0.1M_{sun}_. The gas-phase carbon abundance in the atmosphere of this warm Herbig disk is, at most, moderately depleted compared to the interstellar medium, with Bootis star, with solar abundances of C and O but a strong depletion of rockforming elements. In the gas of the T Tauri disk TW Hya, both C and O are strongly underabundant, with [C]/[H]_gas_=(0.2-5.0)x10^-6^ and C/O>1. We discuss evidence that the gas-phase C and O abundances are high in the warm inner regions of both disks. Our analytical model, including vertical mixing and a grain size distribution, reproduces the observed [C]/[H]_gas_ in the outer disk of TW Hya and allows to make predictions for other systems.
- ID:
- ivo://CDS.VizieR/J/A+A/336/920
- Title:
- HD 163151: a new W UMa type system
- Short Name:
- J/A+A/336/920
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Table 2 contains 408 simultaneous measurements collected in each of the four uvby colours of the Stromgren photometric system for the W UMa system HD 163151. The data are magnitude differences (Du, Dv, Db, Dy, D(b-y), Dm1, Dc1) of the variable star minus comparison star in the standard system versus Heliocentric Julian Day. Tables 3, 4 and 5 are the same, but for H{beta} (65 points), Johnson B data (212 points) and Johnson V data (355 points). The comparison star is HD 166095. The origin in time is the Julian Day 2449858. The observations were carried out (by E. Rodriguez, A. Claret, J.M. Garcia, F.M. Zerbi, R. Garrido, S. Martin, C. Akan, K. Luedeke, V. Keskin, C. Ibanoglu, S. Evren, Z. Tunca, R. Pekunlu, M. Paparo, J. Nuspl, K. Krisciunas and S.Y. Jiang) in 1995 during the course of a multisite campaign. The following telescopes were used: 90cm telescope of the Sierra Nevada Observatory, Spain (uvby-H{beta} photometry); 50cm telescope at the Ege University Observatory, Turkey (BV-uvby); 50cm telescope at Piszkesteto mountain station, Konkoly Observatory, Hungary (BV); 50cm telescope at the Merate Observatory, Italy (V); 30cm telescope at Albuquerque, New Mexico, USA (V) and 15cm telescope at Mauna Kea, Hawaii, USA (V).
- ID:
- ivo://org.gavo.dc/lswscans/res/positions/siap
- Title:
- HDAP -- Heidelberg Digitized Astronomical Plates
- Short Name:
- hdap_siap
- Date:
- 15 Aug 2024 15:17:00
- Publisher:
- The GAVO DC team
- Description:
- Scans of plates kept at Landessternwarte Heidelberg-Königstuhl. They were obtained at location, at the German-Spanish Astronomical Center (Calar Alto Observatory), Spain, and at La Silla, Chile. The plates cover a time span between 1880 and 1999. Specifically, HDAP is essentially complete for the plates taken with the Bruce telescope, the Walz reflector, and Wolf's Doppelastrograph at both the original location in Heidelberg and its later home on Königstuhl.
- ID:
- ivo://CDS.VizieR/J/A+A/635/A94
- Title:
- HD141569A system ALMA and NOEMA data cubes
- Short Name:
- J/A+A/635/A94
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The study of gas-rich debris discs is fundamental to characterising the transition between protoplanetary discs and debris discs. Aims. We determine the physical parameters of the brightest gas-rich debris disc orbiting HD 141569A. We analyse images from the NOrthern Extended Millimeter Array (NOEMA) and the Atacama Large Millimeter/submillimeter Array (ALMA) in ^12^CO, ^13^CO J=2-1, and ^13^CO J=1-0 transitions. We incorporate ALMA archival data of the ^12^CO J=3-2 transition and present continuum maps at 0.87mm, 1.3mm, and 2.8mm. We use simple parametric laws with the Diskfit code and MCMC exploration to characterise the gas disc parameters and report a first attempt to characterise its chemical content with IRAM-30m. The continuum emission is equally shared between a compact (<50au) and a smooth, extended dust component (~350 au). Large millimetre grains seem to dominate the inner regions, while the dust spectral index is marginally larger in the outer region. The ^12^CO is optically thick, while ^13^CO is optically thin with tau_13CO_~0.15 (C^18^O is not detected). The ^13^CO surface density is constrained to be one order of magnitude smaller than around younger Herbig Ae stars, and we derive a gas mass M_12CO_=10^-1^M_{sun}_. We confirm the presence of a small CO cavity (R_CO_=17+/-3au), and find a possibly larger radius for the optically thin ^13^CO J=2-1 transition (35+/-5au). We show that the observed CO brightness asymmetry is coincident with the complex ring structures discovered with VLT/SPHERE in the inner 90au. The ^12^CO temperature T_0_(100au)~30K is lower than expected for a Herbig~A0 star, and could be indicative of subthermal excitation. With the largest amount of dust and gas among hybrid discs, HD141569A shows coincident characteristics of both protoplanetary discs (central regions), and debris discs at large distance. Together with its morphological characteristics and young age, it appears to be a good candidate to witness the transient phase of gas dissipation, with an apparently large gas-to-dust ratio (G/D>100) favouring a faster evolution of dust grains.
7980. HD 146850 atomic lines
- ID:
- ivo://CDS.VizieR/J/A+A/297/503
- Title:
- HD 146850 atomic lines
- Short Name:
- J/A+A/297/503
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the identification of 3 Li-rich giants discovered in an ongoing survey based on IRAS colours. A detailed analysis of one of these, HD 146850, is presented here. High resolution spectra were obtained for this star, using CASPEC at the 3.6m telescope of ESO.