- ID:
- ivo://CDS.VizieR/J/A+A/511/A22
- Title:
- EW Ori differential uvby light curves
- Short Name:
- J/A+A/511/A22
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Recent studies of inactive and active solar-type binaries suggest that chromospheric activity, and its effect on envelope convection, is likely to cause significant radius and temperature discrepancies. Accurate mass, radius, and abundance determinations from additional solar-type binaries exhibiting various levels of activity are needed for a better insight into the structure and evolution of these stars. We aim to determine absolute dimensions and abundances for the G0 V detached eclipsing binary EW Ori, and to perform a detailed comparison with results from recent stellar evolutionary models.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/502/267
- Title:
- EWs of 31 giant stars of 10 open clusters
- Short Name:
- J/A+A/502/267
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Equivalent widths (EWs) of a sample of 31 giant stars of 10 open clusters. The list includes lines of NaI, MgI, SiI, CaI, ScII, TiI, VI, VII, CrI, CrII, FeI, FeII, CoI, NiI, YII, CeII, and EuII. For most of the lines, EWs were measured using PeakFit. For some Fe II lines, EWs were measured by fitting Gaussian profiles to the lines with the IRAF task SPLOT. The adopted oscillator strengths (loggfs) and excitation potentials (EP) are also listed. For the stars of the clusters NGC 2360 and NGC 2447 only the FeII EWs are given. The EWs of the remaining lines can be found in Hamdani et al. (2000, Cat. J/A+A/360/509).
- ID:
- ivo://CDS.VizieR/J/MNRAS/449/761
- Title:
- EWs of metal-poor stars in the UMi I dSph galaxy
- Short Name:
- J/MNRAS/449/761
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present detailed chemical element abundance ratios of 17 elements with eight<=Z<=60 in three metal-poor stars in the Ursa Minor dwarf spheroidal galaxy, which we combine with extant data from the literature to assess the predictions of a novel suite of galaxy chemical evolution models. The spectroscopic data were obtained with the Keck/High-Resolution Echelle Spectrograph instrument and revealed low metallicities of [Fe/H]=-2.12, -2.13 and -2.67 dex. While the most metal-poor star in our sample shows an overabundance of [Mn/Fe] and other Fe-peak elements, our overall findings are in agreement with previous studies of this galaxy: elevated values of the [{alpha}/Fe] ratios that are similar to, or only slightly lower than, the halo values but with SN Ia enrichment at very low metallicity, as well as an enhancement of the ratio of first to second peak neutron capture elements [Y/Ba] with decreasing metallicity. The chemical evolution models which were tailored to reproduce the metallicity distribution function of the dwarf spheroidal, indicate that Ursa Minor had an extended star formation which lasted nearly 5 Gyr with low efficiency and are able to explain the [Y/Ba] enhancement at low metallicity for the first time. In particular, we show that the present-day lack of gas is probably due to continuous loss of gas from the system, which we model as winds.
- ID:
- ivo://CDS.VizieR/J/A+A/512/A13
- Title:
- EW-Teff calibration for solar-type stars
- Short Name:
- J/A+A/512/A13
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The precise determination of the stellar effective temperature of solar type stars is of extreme importance for Astrophysics. We present an effective temperature calibration for FGK dwarf stars using line equivalent width ratios of spectral absorption lines. The ratios of spectral line equivalent width can be very sensitive to effective temperature variations for a well chosen combination of lines. We use the automatic code ARES to measure the equivalent width of several spectral lines, and use these to calibrate with the precise effective temperature derived from spectroscopy presented in a previous work.
- ID:
- ivo://CDS.VizieR/J/AJ/161/80
- Title:
- Excalibur calibration method; HD34411 RVs with EXPRESS
- Short Name:
- J/AJ/161/80
- Date:
- 09 Mar 2022 22:00:00
- Publisher:
- CDS
- Description:
- Excalibur is a nonparametric, hierarchical framework for precision wavelength calibration of spectrographs. It is designed with the needs of extreme-precision radial-velocity (EPRV) instruments in mind, which require calibration or stabilization to better than 10^-4^pixels. Instruments vary along only a few dominant degrees of freedom, especially EPRV instruments that feature highly stabilized optical systems and detectors. Excalibur takes advantage of this property by using all calibration data to construct a low-dimensional representation of all accessible calibration states for an instrument. Excalibur also takes advantage of laser-frequency combs or etalons, which generate a dense set of stable calibration points. This density permits the use of a nonparametric wavelength solution that can adapt to any instrument or detector oddities better than parametric models, such as a polynomial. We demonstrate the success of this method with data from the Extreme Precision Spectrograph (EXPRES), which uses a laser-frequency comb. When wavelengths are assigned to laser comb lines using excalibur, the rms of the residuals is about one-fifth that of wavelengths assigned using polynomial fits to individual exposures. Radial-velocity measurements of HD34411 show a reduction in rms scatter over a 10 month time baseline from 1.17 to 1.05m/s.
- ID:
- ivo://CDS.VizieR/J/AZh/81/33
- Title:
- Excitation of PtI transitions
- Short Name:
- J/AZh/81/33
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have experimentally studied the excitation of transitions of the platinum atom ending in levels of the ^3^D main term. The atoms were excited by a 30 eV monoenergetic electron beam. The lines studied are located at wavelengths of 204-367nm. The largest of the measured excitational cross sections exceed 10^-16^cm^2^. The optical-excitation functions measured at electron energies of 0-200eV have complex structures.
- ID:
- ivo://CDS.VizieR/J/ApJS/123/311
- Title:
- Excitation rate coefficients for O III
- Short Name:
- J/ApJS/123/311
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Collision strengths for fine-structure transitions among the levels of the (1s^2^) 2s^2^2p^2^, 2s2p^3^, 2p^4^, 2s^2^2p3s, 2s^2^2p3p, and 2s^2^2p3d configurations of O III have been computed over a wide range of energies below 13.0 ryd using the R-matrix program. All partial waves with L{<=}40 have been included to ensure the convergence of results. Excitation rate coefficients, in the form of dimensionless effective collision strengths, have also been computed at temperatures below 200,000 K. The results are compared with available calculations, and accuracy of the data is assessed.
- ID:
- ivo://CDS.VizieR/J/A+A/407/769
- Title:
- Excitation rates for transitions in Ca XV
- Short Name:
- J/A+A/407/769
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Collision strengths for transitions among the energetically lowest 46 fine-structure levels belonging to the (1s^2^) 2s^2^2p^2^, 2s2p^3^, 2p^4^, and 2s^2^2p3l configurations of Ca XV are computed, over a wide electron energy range below 300Ryd, using the Dirac Atomic R-matrix Code (DARC) of Norrington & Grant (2003, Comput. Phys. Comm., in preparation). Resonances in the threshold region have been resolved in a fine energy mesh, and excitation rates are determined over a wide electron temperature range below 10^7^K. The results are compared with those available in the literature, and the accuracy of the data is assessed.
- ID:
- ivo://CDS.VizieR/J/MNRAS/451/74
- Title:
- Excited-state hydroxyl maser polarimetry
- Short Name:
- J/MNRAS/451/74
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present polarimetric maser observations with the Australia Telescope Compact Array of excited-state hydroxyl (OH) masers. We observed 30 fields of OH masers in full Stokes polarization with the Compact Array Broadband Backend at both the 6030 and 6035 MHz excited-state OH transitions, and the 6668 MHz methanol maser transition, detecting 70 sites of maser emission. Amongst the OH we found 112 Zeeman pairs, of which 18 exhibited candidate {pi} components. This is the largest single full polarimetric study of multiple sites of star formation for these frequencies, and the rate of 16 percent {pi} components clearly indicates that the {pi} component exists, and is comparable to the percentage recently found for ground-state transitions. This significant percentage of {pi} components, with consistent proportions at both ground- and excited-state transitions, argues against Faraday rotation suppressing the {pi} component emission. Our simultaneous observations of methanol found the expected low level of polarization, with no circular detected, and linear only found at the =<10 percent level for the brightest sources.
- ID:
- ivo://CDS.VizieR/J/MNRAS/461/1576
- Title:
- EX Hya mid-eclipse timings
- Short Name:
- J/MNRAS/461/1576
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A study on the intermediate polar EX Hya is presented, based on simultaneous photometry and high-dispersion spectroscopic observations, during four consecutive nights. The strong photometric modulation related to the 67-min spin period of the primary star is clearly present, as well as the narrow eclipses associated with the orbital modulation. Since our eclipse timings have been obtained almost 91000 cycles since the last reported observations, we present new linear ephemeris, although we cannot rule out a sinusoidal variation suggested by previous authors.