- ID:
- ivo://CDS.VizieR/J/ApJ/751/73
- Title:
- Equivalent widths in {eta} Cat in 1998-2012
- Short Name:
- J/ApJ/751/73
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Stellar wind-emission features in the spectrum of eta Carinae have decreased by factors of 1.5-3 relative to the continuum within the last 10 years. We investigate a large data set from several instruments (STIS, GMOS, UVES) obtained between 1998 and 2011 and analyze the progression of spectral changes in direct view of the star, in the reflected polar-on spectra at FOS4, and at the Weigelt knots. We find that the spectral changes occurred gradually on a timescale of about 10 years and that they are dependent on the viewing angle. The line strengths declined most in our direct view of the star. About a decade ago, broad stellar wind-emission features were much stronger in our line-of-sight view of the star than at FOS4. After the 2009 event, the wind-emission line strengths are now very similar at both locations. High-excitation He I and N II absorption lines in direct view of the star strengthened gradually. The terminal velocity of Balmer P Cyg absorption lines now appears to be less latitude dependent, and the absorption strength may have weakened at FOS4. Latitude-dependent alterations in the mass-loss rate and the ionization structure of eta Carinae's wind are likely explanations for the observed spectral changes.
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- ID:
- ivo://CDS.VizieR/J/A+A/588/A120
- Title:
- Equivalent widths in 10 open clusters
- Short Name:
- J/A+A/588/A120
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Open clusters are distributed all across the disk and are convenient tracers of its properties. In particular, outer disk clusters bear a key role for the investigation of the chemical evolution of the Galactic disk. The goal of this study is to derive homogeneous elemental abundances for a sample of ten outer disk OCs, and investigate possible links with disk structures such as the Galactic Anticenter Stellar Structure. We analyse high-resolution spectra of red giants, obtained from the HIRES@Keck and UVES@VLT archives. We derive elemental abundances and stellar atmosphere parameters by means of the classical equivalent width method. We also performed orbit integrations using proper motions. The Fe abundances we derive trace a shallow negative radial metallicity gradient of slope -0.027+/-0.007dex/kpc in the outer 12kpc of the disk. The [alpha/Fe] gradient appears flat, with a slope of 0.006+/-0.007dex/kpc. The two outermost clusters (Be 29 and Sau 1) appear to follow elliptical orbits. Be 20 also exhibits a peculiar orbit with a large excursion above the plane. The irregular orbits of the three most metal-poor clusters (two of which are located at the edge of the Galactic disk), if confirmed by more robust astrometric measurements such as those of the Gaia mission, are compatible with an inside-out formation scenario for the Milky Way, in which extragalactic material is accreted onto the outer disk. We cannot determine if Be 20, Be 29, and Sau 1 are of extragalactic origin, as they may be old genuine Galactic clusters whose orbits were perturbed by accretion events or minor mergers in the past 5Gyr, or they may be representants of the thick disk population. The nature of these objects is intriguing and deserves further investigations in the near future.
- ID:
- ivo://CDS.VizieR/J/A+AS/42/391
- Title:
- Equivalent Widths in Pollux
- Short Name:
- J/A+AS/42/391
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- (no description available)
- ID:
- ivo://CDS.VizieR/J/ApJS/126/461
- Title:
- Equivalent Widths in the Spectrum of Sirius
- Short Name:
- J/ApJS/126/461
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The equivalent widths of total 546 lines (26 elements are included) in the spectrum of the bright Am star Sirius from 380 to 930 nm are tabulated. The high-resolution, high signal-to-noise ratio spectrum was obtained with the Coude Echelle Spectrograph attached to the 2.16 m telescope at Beijing Astronomical Observatory (Xinglong, China). Here we also give the results of the equivalent widths comparison between our measurements and those of Strom et al. (=1966ApJ...146..880S) and Sadakane & Ueta (=1989PASJ...41..279S). Table 1. Observation Journal of Sirius: ---------------------------------------------------------------------------- Spectral Range Exposure Time Geocentric Radial Velocity (nm) Obs. Date (s) (km s-1) ---------------------------------------------------------------------------- 386.5-572.1 1997 Feb 18/19 180 12.75 (0.45) 383.3-661.9 1997 Feb 18/19 40+40+30 12.37 (0.96) 378.9-551.6 1997 Feb 18/19 40+40 12.31 (0.82) 380.7-649.3 1997 Feb 18/19 40+40 12.42 (0.93) 623.8-922.7 1999 Apr 01/02 300+300 15.49 (0.52) 624.8-930.4 1999 Apr 01/02 300+300 15.58 (0.69) ----------------------------------------------------------------------------
- ID:
- ivo://CDS.VizieR/J/AZh/81/658
- Title:
- Equivalent widths of 9 barium stars
- Short Name:
- J/AZh/81/658
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present our analysis of elemental abundances in the atmospheres of 16 classical barium stars derived from high-resolution spectra and model atmospheres. Comparison of the results with analogous data for moderate barium stars and normal red giants shows that the abundance patterns for elements before the iron peak are the same for all three groups of red giants, testifying to a similar origin. For binary systems, we confirm the influence of the orbital period and, hence, the component separation, on the overabundance of s-process elements. The amount of enrichment in s-process elements is also in influenced by mass, metallicity, and evolutionary phase. Any of these parameters can be important in individual objects.
- ID:
- ivo://CDS.VizieR/J/A+A/377/123
- Title:
- Equivalent widths of 6 binaries
- Short Name:
- J/A+A/377/123
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We performed a careful differential abundance analysis of individual components of six main sequence binaries with separations of a few hundreds of AU. To reduce analysis concerns, we selected systems with almost equal mass components. We were able to derive differential abundances of several elements with errors down to 0.01dex in the best cases. We found that in four systems the two components have the same chemical composition, within these very severe limits. However, clear differences were found for the two remaining systems (HD 219542 and HD 200466), in both cases the primaries being more Fe-rich than the secondaries, by 0.091+/-0.009 and 0.053+/-0.024dex respectively. Similar differences were found for most of the elements considered in our analysis; however, we found no appreciable difference for volatile elements and a trend for increasing abundance differences with increasing condensation temperature for individual elements, a result similar to that found for some single stars with planets by Smith et al. (2001AJ....121.3207S). Finally, we note that HD 219542A has a Li-abundance comparable to those of Li-rich stars in old open clusters, while no Li is detected in the slightly cooler HD 219542B. We suggest that the primaries of these two systems have accreted rocky planets or the inner dust-rich part of a protoplanetary disk, likely due to gravitational perturbation caused by the presence of the companion.
- ID:
- ivo://CDS.VizieR/J/A+A/549/A129
- Title:
- Equivalent widths of cool stars
- Short Name:
- J/A+A/549/A129
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The near-infrared (NIR) wavelength range offers some unique spectral features, and it is less prone to the extinction than the optical one. Recently, the first flux calibrated NIR library of cool stars from the NASA Infrared Telescope Facility (IRTF) have become available, and it has not been fully exploited yet. We want to develop spectroscopic diagnostics for stellar physical parameters based on features in the wavelength range 1-5um. In this work we test the technique in the I and K bands. The study of the Y, J, H, and L bands will be presented in the following paper. An objective method for semi-empirical definition of spectral features sensitive to various physical parameters is applied to the spectra. It is based on sensitivity map - i.e., derivative of the flux in the spectra with respect to the stellar parameters at a fixed wavelength. New optimized indices are defined and their equivalent widths (EWs) are measured.
- ID:
- ivo://CDS.VizieR/J/A+A/555/A25
- Title:
- Equivalent widths of DIBs
- Short Name:
- J/A+A/555/A25
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Stellar spectroscopic surveys may bring useful statistical information on the links between diffuse interstellar bands (DIBs) and the interstellar environment. DIB databases can also be used as a complementary tool for locating interstellar (IS) clouds. Our goal is to develop fully automated methods of DIB measurements to be applied to extensive data from stellar surveys. We present a method that is appropriate for early-type nearby stars, along with its application to high-resolution spectra of ~130 targets recorded with the ESO FEROS spectrograph and comparisons with other determinations. Using a DIB average profile deduced from the most reddened stars, we performed an automated fitting of a combination of a smooth stellar continuum, the DIB profile, and, when necessary, a synthetic telluric transmission.
- ID:
- ivo://CDS.VizieR/J/ApJ/850/194
- Title:
- Equivalent widths of 8 DIBs for 186 O & B stars
- Short Name:
- J/ApJ/850/194
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We study the behavior of eight diffuse interstellar bands (DIBs) in different interstellar environments, as characterized by the fraction of hydrogen in molecular form (f_H2_), with comparisons to the corresponding behavior of various known atomic and molecular species. The equivalent widths of the five "normal" DIBs ({lambda}{lambda}5780.5, 5797.1, 6196.0, 6283.8, and 6613.6), normalized to E_B-V_, show a "lambda-shaped" behavior: they increase at low f_H2_, peak at f_H2_~0.3, and then decrease. The similarly normalized column densities of Ca, Ca+, Ti+, and CH+ also decline for f_H2_>0.3. In contrast, the normalized column densities of Na, K, CH, CN, and CO increase monotonically with fH2, and the trends exhibited by the three C_2_ DIBs ({lambda}{lambda}4726.8, 4963.9, and 4984.8) lie between those two general behaviors. These trends with f_H2_ are accompanied by cosmic scatter, the dispersion at any given f_H2_ being significantly larger than the individual errors of measurement. The lambda-shaped trends suggest the balance between creation and destruction of the DIB carriers differs dramatically between diffuse atomic and diffuse molecular clouds; additional processes aside from ionization and shielding are needed to explain those observed trends. Except for several special cases, the highest W{lambda}(5780)/W{lambda}(5797) ratios, characterizing the so-called "sigma-zeta effect," occur only at f_H2_<0.2. We propose a sequence of DIBs based on trends in their pair-wise strength ratios with increasing f_H2_. In order of increasing environmental density, we find the {lambda}6283.8 and {lambda}5780.5 DIBs, the {lambda}6196.0 DIB, the {lambda}6613.6 DIB, the {lambda}5797.1 DIB, and the C_2_ DIBs.
- ID:
- ivo://CDS.VizieR/J/MNRAS/396/2061
- Title:
- Equivalent widths of EP UMA (HR 4330)
- Short Name:
- J/MNRAS/396/2061
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The chemically peculiar star HR 4330 (=HD 96707, EP UMa) was observed using the 2-m Himalayan Chandra Telescope at the Indian Astronomical Observatory, Hanle, India, for studying the variations in its spectral features. It was found that the spectral features of CaII 3933{AA} and SrII 4077{AA} were showing rapid variations in their equivalent widths with a periodicity of 0.28+/-0.02d. Such short-term variations suggest that there could be a dynamically active surface with rapid variation in the conditions of the stellar atmosphere.