- ID:
- ivo://CDS.VizieR/J/AZh/71/572
- Title:
- Spectroscopic observations of V380 Ori
- Short Name:
- J/AZh/71/572
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The results of spectral observations of the Ae/Be star V380 Ori in the optical and near-IR ranges for 1976 to 1991, are presented. The spectra were obtained on various telescopes and spectrographs including the Main Stellar Spectrograph of the BTA six-meter telescope. For 270 bright emission lines, the intensities, equivalent widths, half-widths, radial velocities, and variability amplitudes are given.
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- ID:
- ivo://CDS.VizieR/J/ApJ/841/7
- Title:
- Spectroscopic obs & members of ZwCl 2341+0000
- Short Name:
- J/ApJ/841/7
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- ZwCl 2341.1+0000, a merging galaxy cluster with disturbed X-ray morphology and widely separated (~3Mpc) double radio relics, was thought to be an extremely massive (10-30x10^14^M_{sun}_) and complex system, with little known about its merger history. We present JVLA 2-4GHz observations of the cluster, along with new spectroscopy from our Keck/DEIMOS survey, and apply Gaussian Mixture Modeling to the three-dimensional distribution of 227 confirmed cluster galaxies. After adopting the Bayesian Information Criterion to avoid overfitting, which we discover can bias high the total dynamical mass estimates, we find that a three-substructure model with a total dynamical mass estimate of 9.39+/-0.81x10^14^M_{sun}_ is favored. We also present deep Subaru imaging and perform the first weak lensing analysis on this system, obtaining a weak lensing mass estimate of 5.57+/-2.47x10^14^M_{sun}_. This is a more robust estimate because it does not depend on the dynamical state of the system, which is disturbed due to the merger. Our results indicate that ZwCl2341.1+0000 is a multiple merger system comprised of at least three substructures, with the main merger that produced the radio relics occurring near the plane of the sky, and a younger merger in the north occurring closer to the line of sight. Dynamical modeling of the main merger reproduces observed quantities (relic positions and polarizations, subcluster separation and radial velocity difference), if the merger axis angle of ~10_-6_^+34^ degrees and the collision speed at pericenter is ~1900_-200_^+300^km/s.
- ID:
- ivo://CDS.VizieR/J/ApJ/842/97
- Title:
- Spectroscopic obs. of 413 HII regions in M33
- Short Name:
- J/ApJ/842/97
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The spectra of 413 star-forming (or H II) regions in M33 (NGC 598) were observed using the multifiber spectrograph of Hectospec at the 6.5m Multiple Mirror Telescope. Using this homogeneous spectra sample, we measured the intensities of emission lines and some physical parameters, such as electron temperatures, electron densities, and metallicities. Oxygen abundances were derived via the direct method (when available) and two empirical strong-line methods, namely, O3N2 and N2. At the high-metallicity end, oxygen abundances derived from the O3N2 calibration were higher than those derived from the N2 index, indicating an inconsistency between O3N2 and N2 calibrations. We present a detailed analysis of the spatial distribution of gas-phase oxygen abundances in M33 and confirm the existence of the axisymmetric global metallicity distribution that is widely assumed in the literature. Local variations were also observed and subsequently associated with spiral structures to provide evidence of radial migration driven by arms. Our O/H gradient fitted out to 1.1 R_25_ resulted in slopes of -0.17+/-0.03, -0.19+/-0.01, and -0.16+/-0.17dex R_25_^-1^, utilizing abundances from O3N2, N2 diagnostics, and a direct method, respectively.
- ID:
- ivo://CDS.VizieR/J/ApJ/837/176
- Title:
- Spectroscopic obs. of 2 red giant stars in omega Cen
- Short Name:
- J/ApJ/837/176
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a chemical abundance analysis of a metal-poor star, ROA276, in the stellar system {omega} Centauri. We confirm that this star has an unusually high [Sr/Ba] abundance ratio. Additionally, ROA 276 exhibits remarkably high abundance ratios, [X/Fe], for all elements from Cu to Mo along with normal abundance ratios for the elements from Ba to Pb. The chemical abundance pattern of ROA 276, relative to a primordial {omega} Cen star ROA 46, is best fit by a fast-rotating low-metallicity massive stellar model of 20M_{sun}_, [Fe/H]=-1.8, and an initial rotation 0.4 times the critical value; no other nucleosynthetic source can match the neutron-capture element distribution. ROA 276 arguably offers the most definitive proof to date that fast-rotating massive stars contributed to the production of heavy elements in the early universe.
- ID:
- ivo://CDS.VizieR/J/ApJ/881/104
- Title:
- Spectroscopic obs. of RR Lyrae in NGC5139
- Short Name:
- J/ApJ/881/104
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a detailed spectroscopic analysis of RR Lyrae (RRL) variables in the globular cluster NGC5139 ({omega} Cen). We collected optical (4580-5330{AA}), high-resolution (R~34000), high signal-to-noise ratio (~200) spectra for 113 RRLs with the multifiber spectrograph M2FS at the Magellan/Clay Telescope at Las Campanas Observatory. We also analyzed high- resolution (R~26000) spectra for 122 RRLs collected with FLAMES/GIRAFFE at the Very Large Telescope, available in the ESO archive. The current sample doubles the literature abundances of cluster and field RRLs in the Milky Way based on high-resolution spectra. Equivalent-width measurements were used to estimate atmospheric parameters, iron, and abundance ratios for {alpha} (Mg, Ca, Ti), iron peak (Sc, Cr, Ni, Zn), and s-process (Y) elements. We confirm that {omega}Cen is a complex cluster, characterized by a large spread in the iron content: -2.58<~[Fe/H]<~-0.85. We estimated the average cluster abundance as <[Fe/H]>=-1.80{+/-}0.03, with {sigma}=0.33dex. Our findings also suggest that two different RRL populations coexist in the cluster. The former is more metal-poor ([Fe/H]<~-1.5), with almost solar abundance of Y. The latter is less numerous, more metal-rich, and yttrium enhanced ([Y/Fe]>~0.4). This peculiar bimodal enrichment only shows up in the s-process element, and it is not observed among lighter elements, whose [X/Fe] ratios are typical for Galactic globular clusters.
- ID:
- ivo://CDS.VizieR/J/MNRAS/412/1741
- Title:
- Spectroscopic obs. of 3 spiral galaxies
- Short Name:
- J/MNRAS/412/1741
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The correlation between the breaks in the metallicity distribution and the corotation radius of spiral galaxies has been already advocated in the past and is predicted by a chemodynamical model of our Galaxy that effectively introduces the role of spiral arms in the star formation rate. In this work, we present photometric and spectroscopic observations made with the Gemini Telescope for three of the best candidates of spiral galaxies to have the corotation inside the optical disc: IC 0167, NGC 1042 and NGC 6907. We observed the most intense and well-distributed HII regions of these galaxies, deriving reliable galactocentric distances and oxygen abundances by applying different statistical methods. From these results, we confirm the presence of variations in the gradients of metallicity of these galaxies that are possibly correlated with the corotation resonance.
- ID:
- ivo://CDS.VizieR/J/A+A/531/A89
- Title:
- Spectroscopic orbit of Capella
- Short Name:
- J/A+A/531/A89
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Capella is among the few binary stars with two evolved giant components. The hotter component is a chromospherically active star within the Hertzsprung gap, while the cooler star is possibly helium-core burning. The known inclination of the orbital plane from astrometry in combination with precise radial velocities will allow very accurate masses to be determined for the individual Capella stars. This will constrain their evolutionary stage and possibly the role of the active star's magnetic field on the dynamical evolution of the binary system. We obtained a total of 438 high-resolution echelle spectra during the years 2007-2010 and used the measured velocities to recompute the orbital elements. Our double-lined orbital solution yields average residuals of 64m/s for the cool component and 297m/s for the more rapidly rotating hotter component.
- ID:
- ivo://CDS.VizieR/J/AJ/152/46
- Title:
- Spectroscopic orbits for 15 late-type stars
- Short Name:
- J/AJ/152/46
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Spectroscopic orbital elements are determined for 15 stars with periods from 8 to 6528days with six orbits computed for the first time. Improved astrometric orbits are computed for two stars and one new orbit is derived. Visual orbits were previously determined for four stars, four stars are members of multiple systems, and five stars have Hipparcos "G" designations or have been resolved by speckle interferometry. For the nine binaries with previous spectroscopic orbits, we determine improved or comparable elements. For HD28271 and HD200790, our spectroscopic results support the conclusions of previous authors that the large values of their mass functions and lack of detectable secondary spectrum argue for the secondary in each case being a pair of low-mass dwarfs. The orbits given here may be useful in combination with future interferometric and Gaia satellite observations.
- ID:
- ivo://CDS.VizieR/J/AJ/156/117
- Title:
- Spectroscopic orbits for late-type stars. II.
- Short Name:
- J/AJ/156/117
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have determined spectroscopic orbital elements for 13 systems - 10 single-lined binaries and three double-lined binaries. For the three binaries with previously published spectroscopic orbits, we have computed improved or comparable elements. While two systems have relatively short periods between 10 and 19 days, the remaining systems have much longer periods ranging from 604 to 9669 days. One of the single-lined systems, HD 142640, shows both short-period and long-period velocity variations and so is triple. For three systems - HD 59380, HD 160933, and HD 161163 - we have combined our spectroscopic results with Hipparcos astrometric observations to obtain astrometric orbits. For HD 14802 we have determined a joint orbital solution from spectroscopic velocities and interferometric observations. The orbits given here will be useful in combination with future interferometric and Gaia satellite observations.
- ID:
- ivo://CDS.VizieR/J/ApJ/466/415
- Title:
- Spectroscopic orbits for three binaries
- Short Name:
- J/ApJ/466/415
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present orbital solutions for three low-amplitude spectroscopic binaries discovered in a sample of 20 solar-type IAU radial velocity standard stars observed with the Digital Speedometers at the Harvard- Smithsonian Center for Astrophysics. We update the orbital solutions for HD 114762 and HD 140913, and present a preliminary new solution for HD 29587. For all three orbits, the minimum mass for the secondary is less than 0.08M_{sun}_, the borderline between stellar and substellar masses. We consider the probability that all three binaries have small enough inclination angles so that their companions are above the substellar limit. To do so, we treat the 20 IAU standards as a sample drawn from a population of binaries with a mass-ratio distribution that does not allow any substellar companions. We calculate the probability that such a sample could still have three binaries, with the low-amplitude orbits actually found within the IAU sample. We show that this probability is small, depending on the specific mass-ratio distribution. For example, a flat mass-ratio distribution that assumes there are no substellar companions can be excluded at a high confidence level, 99.7%. We further show that our three detections may imply that the secondary-mass distribution rises near the substellar limit. However, the observations do not yet allow us to distinguish whether the unseen companions of HD 114762, HD 140913, and HD 29587 have stellar or substellar masses. In particular, recent attempts to estimate the mass of the companion of HD 114762 based on assumptions about the intrinsic rotation of the primary are inconclusive, and the companion could easily have a mass as low as 0.02M_{sun}_. We compare our three detections with the null results of four very precise radial velocity searches for substellar companions. The difference is indeed puzzling but can be accounted for if just a small fraction of the solar-type stars, of the order of a few percent, have companions with masses near the substellar limit.