- ID:
- ivo://CDS.VizieR/J/ApJ/679/1549
- Title:
- Spectroscopy of metal-poor star CS 17435-00532
- Short Name:
- J/ApJ/679/1549
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first detailed abundance analysis of the metal-poor giant HKII 17435-00532. This star was observed as part of the University of Texas long-term project Chemical Abundances of Stars in the Halo (CASH). A spectrum was obtained with the High Resolution Spectrograph (HRS) on the Hobby-Eberly Telescope with a resolving power of R~15000. Our analysis reveals that this star may be located on the red giant branch, red horizontal branch, or early asymptotic giant branch. We find that this metal-poor ([Fe/H]=-2.2) star has an unusually high lithium abundance [log{epsilon}(Li)=+2.1], mild carbon ([C/Fe]=+0.7) and sodium ([Na/Fe]=+0.6) enhancement, as well as enhancement of both s-process ([Ba/Fe]=+0.8) and r-process ([Eu/Fe]=+0.5) material.
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- ID:
- ivo://CDS.VizieR/J/ApJ/769/10
- Title:
- Spectroscopy of M31 globular clusters
- Short Name:
- J/ApJ/769/10
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the results of an [OIII]{lambda}5007 spectroscopic survey for planetary nebulae (PNe) located within the star clusters of M31. By examining R~5000 spectra taken with the WIYN+Hydra spectrograph, we identify 3 PN candidates in a sample of 274 likely globular clusters, 2 candidates in objects which may be globular clusters, and 5 candidates in a set of 85 younger systems. The possible PNe are all faint, between ~2.5 and ~6.8mag down the PN luminosity function, and, partly as a consequence of our selection criteria, have high excitation, with [OIII]{lambda}5007 to H{beta} ratios ranging from 2 to >~12. We discuss the individual candidates, their likelihood of cluster membership, and the possibility that they were formed via binary interactions within the clusters. Our data are consistent with the suggestion that PN formation within globular clusters correlates with binary encounter frequency, though, due to the small numbers and large uncertainties in the candidate list, this study does not provide sufficient evidence to confirm the hypothesis.
- ID:
- ivo://CDS.VizieR/J/A+AS/131/479
- Title:
- Spectroscopy of MWC 297
- Short Name:
- J/A+AS/131/479
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- On the basis of spectroscopic CCD material obtained at the Haute Provence Observatory, we provide line identifications and equivalent width measurements in the wavelength region 4100-8900{AA} of the spectrum of MWC 297. About two hundred features are identified, almost exclusively emission lines. Only one interstellar feature could be identified ({lambda}6613) a fact which contrasts with the eigth magnitudes of extinction found by photometrists. The spectrum of the underlying star corresponds probably to a late O or early B-type object. The cooler emission lines correspond to a spectrum of a middle A-type star. Analogies with other stars observed in this series of papers are examined.
- ID:
- ivo://CDS.VizieR/J/A+AS/120/99
- Title:
- Spectroscopy of MWC 645
- Short Name:
- J/A+AS/120/99
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We analyse spectroscopic CCD material obtained at the Haute Provence Observatory. We provide identifications and equivalent width measurements in the wavelength region 3740-8790. About 350 emissions lines were measured and about 88 of them were identified. A comparison of our results with those of other authors is provided, as well as a table of elements identified in the spectrum of this star. The pattern of elements present is analogous to that of a late B-type star, but some exceptions are noted, such as the absence of Ne and Mg lines and the presence of K, Cu and Zr lines which appear usually in later type stars. We review the little which is known concerning this object and we also present a quantitative account of the variations in equivalent widths. The observations indicate that the spectrum is highly variable, so that in two different years only half of the lines appear on both spectra. Furthermore variations by at least a factor of two in the equivalent widths are present in many lines. The radial velocity derived from the emission lines (-76km/s) corresponds to that of the shell which probably has a velocity of about 50km/s with respect to the underlying star.
- ID:
- ivo://CDS.VizieR/J/A+AS/118/495
- Title:
- Spectroscopy of MWC 349 A
- Short Name:
- J/A+AS/118/495
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We analyse spectroscopic CCD material obtained at the Haute Provence Observatory. We provide line identifications and equivalent width measurements in the wavelength region 3700-8790A. Over 300 emission features are identified and a comparison of our results with those of other authors is provided, as well as a table of all elements which have been identified in the spectrum of the object. The pattern of elements present is analogous to that of B-type stars, but some exceptions are noted, such as the absence of C, Al and Mn. We review the present knowledge of the spectrum variability of MWC 349A. The observations indicate th at the equivalent widths of the lines of many elements vary by factors of up to two. We also provide a list of diffuse interstellar features observed. The latter lead to an average (B-V) excess of about two magnitudes, which is less than what is expected for an object having an interstellar extinction of 10-11 magnitudes.
- ID:
- ivo://CDS.VizieR/J/A+AS/128/475
- Title:
- Spectroscopy of MWC 158 = HD 50138
- Short Name:
- J/A+AS/128/475
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- On the basis of spectroscopic CCD material obtained at the Haute Provence Observatory, we provide line identifications and equivalent width measurements in the wavelength region 3738-10232 A of the spectrum of HD 50138 Over two hundred features are identified and a comparison of our results with those of other authors is provided. We also discuss the variability of the lines using equivalent widths and descriptions of the line spectrum. We attribute as a best compromise a spectral type of B 5 III. We conclude that the gaseous shell surrounding the star has a temperature of the order of 10 000K and that its distance to the star is of the order of two stellar radii. We discuss the relation of this star to others previously analyzed and warn against hasty generalizations.
- ID:
- ivo://CDS.VizieR/J/AJ/147/20
- Title:
- Spectroscopy of 447 nearby M dwarfs
- Short Name:
- J/AJ/147/20
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present metallicities, radial velocities, and near-infrared (NIR) spectral types for 447 M dwarfs determined from moderate resolution (R{approx}2000) NIR spectra obtained with the NASA Infrared Telescope Facility (IRTF)/SpeX. These M dwarfs are primarily targets of the MEarth Survey, a transiting planet survey searching for super Earths around mid-to-late M dwarfs within 33pc. We present NIR spectral types for each star and new spectral templates for the IRTF in the Y, J, H, and K-bands, created using M dwarfs with near-solar metallicities. We developed two spectroscopic distance calibrations that use NIR spectral type or an index based on the curvature of the K-band continuum. Our distance calibration has a scatter of 14%. We searched 27 NIR spectral lines and 10 spectral indices for metallicity sensitive features, taking into account correlated noise in our estimates of the errors on these parameters. We calibrated our relation using 36 M dwarfs in common proper pairs with an F-, G-, or K-type star of known metallicity. We validated the physical association of these pairs using proper motions, radial velocities, and spectroscopic distance estimates. Our resulting metallicity calibration uses the sodium doublet at 2.2{mu}m as the sole indicator for metallicity. It has an accuracy of 0.12dex inferred from the scatter between the metallicities of the primaries and the estimated metallicities of the secondaries. Our relation is valid for NIR spectral types from M1V to M5V and for -1.0dex<[Fe/H]<+0.35dex. We present a new color-color metallicity relation using J-H and J-K colors that directly relates two observables: the distance from the M dwarf main sequence and equivalent width of the sodium line at 2.2{mu}m. We used radial velocities of M dwarf binaries, observations at different epochs, and comparison between our measurements and precisely measured radial velocities to demonstrate a 4km/s accuracy.
- ID:
- ivo://CDS.VizieR/J/AJ/143/126
- Title:
- Spectroscopy of 462 nearby Type Ia supernovae
- Short Name:
- J/AJ/143/126
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present 2603 spectra of 462 nearby Type Ia supernovae (SNe Ia), including 2065 previously unpublished spectra, obtained during 1993-2008 through the Center for Astrophysics Supernova Program. There are on average eight spectra for each of the 313 SNe Ia with at least two spectra. Most of the spectra were obtained with the FAST spectrograph at the Fred Lawrence Whipple Observatory 1.5m telescope and reduced in a consistent manner, making this data set well suited for studies of SN Ia spectroscopic diversity. Using additional data from the literature, we study the spectroscopic and photometric properties of SNe Ia as a function of spectroscopic class using the classification schemes of Branch et al. (2006PASP..118..560B) and Wang et al. (2009, Cat. J/ApJ/699/L139). The width-luminosity relation appears to be steeper for SNe Ia with broader lines, although the result is not statistically significant with the present sample. Based on the evolution of the characteristic SiII{lambda}6355 line, we propose improved methods for measuring velocity gradients, revealing a larger range than previously suspected, from ~0 to ~400km/s/day considering the instantaneous velocity decline rate at maximum light.
- ID:
- ivo://CDS.VizieR/J/AJ/149/15
- Title:
- Spectroscopy of NGC 7789
- Short Name:
- J/AJ/149/15
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have obtained high-resolution spectra of 32 giants in the open cluster NGC 7789 using the Wisconsin-Indiana-Yale-NOAO Hydra spectrograph. We explore differences in atmospheric parameters and elemental abundances caused by the use of the linelist developed for the Gaia-ESO Survey (GES) compared to one based on Arcturus used in our previous work. [Fe/H] values decrease when using the GES linelist instead of the Arcturus-based linelist; these differences are probably driven by systematically lower (~-0.1dex) GES surface gravities. Using the GES linelist we determine abundances for 10 elements--Fe, Mg, Si, Ca, Ti, Na, Ni, Zr, Ba, and La. We find the cluster's average metallicity [Fe/H]=0.03+/-0.07dex, in good agreement with literature values, and a lower [Mg/Fe] abundance than has been reported before for this cluster (0.11+/-0.05dex). We also find the neutron-capture element barium to be highly enhanced--[Ba/Fe]=+0.48+/-0.08--and disparate from cluster measurements of neutron-capture elements La and Zr (-0.08+/-0.05 and 0.08+/-0.08, respectively). This is in accordance with recent discoveries of supersolar Ba enhancement in young clusters along with more modest enhancement of other neutron-capture elements formed in similar environments.
- ID:
- ivo://CDS.VizieR/J/AJ/146/39
- Title:
- Spectroscopy of NGC 5822-2 and NGC 5822-201
- Short Name:
- J/AJ/146/39
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Open clusters are very useful examples to explain the constraint of the nucleosynthesis process with the luminosities of stars because the distances of the clusters are better known than those of field stars. We carried out a detailed spectroscopic analysis to derive the chemical composition of two red giants in the young open cluster NGC 5822, NGC 5822-2, and NGC 5822-201. We obtained abundances of C, N, O, Na, Mg, Al, Ca, Si, Ti, Ni, Cr, Y, Zr, La, Ce, and Nd. The atmospheric parameters of the studied stars and their chemical abundances were determined using high-resolution optical spectroscopy. We employed the local thermodynamic equilibrium model atmospheres of Kurucz and the spectral analysis code MOOG. The abundances of the light elements were derived using the spectral synthesis technique. We found that NGC 5822-2 and -201 have, respectively, a mean overabundance of the elements created by the s-process, "s," with the notation [s/Fe] of 0.77+/-0.12 and 0.83+/-0.05. These values are higher than those for field giants of similar metallicity. We also found that NGC 5822-2 and -201 have, respectively, luminosities of 140L_{sun}_ and 76L_{sun}_, which are much lower than the luminosity of an asymptotic giant branch star. We conclude that NGC 5822-2 and NGC 5822-201 are two new barium stars first identified in the open cluster NGC 5822. The mass transfer hypothesis is the best scenario to explain the observed overabundances.
