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- ID:
- ivo://CDS.VizieR/J/AJ/127/373
- Title:
- Elemental abundances of 3 red giants in Ter 7
- Short Name:
- J/AJ/127/373
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Chemical abundances in three giants in Terzan 7, a globular cluster associated with the Sagittarius dwarf galaxy, have been determined using high-resolution spectra obtained with the UVES spectrograph on the ESO 8.2m Kueyen telescope. We find the overall metallicity of the stars to be [Fe/H]=-0.61+/-0.07, which is slightly higher than that previously evaluated from photometry and used for the age determination of this cluster. This metallicity yields an age of about 6Gyr, which is slightly lower than derived from previous estimates. The relative abundance ratios of various chemical elements to iron lie between those of its host galaxy's metal-poor and metal-rich stars and reveal an intriguing similarity to the pattern seen in the Large Magellanic Cloud.
- ID:
- ivo://CDS.VizieR/J/AJ/159/46
- Title:
- Elemental abundances of 416 stars in 5 dSphs of M31
- Short Name:
- J/AJ/159/46
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present deep spectroscopy from Keck/DEIMOS (DEep Imaging Multi-Object Spectrograph) of Andromeda I, III, V, VII, and X, all of which are dwarf spheroidal satellites (dSphs) of M31. The sample includes 256 spectroscopic members across all five dSphs. We confirm previous measurements of the velocity dispersions and dynamical masses, and we provide upper limits on bulk rotation. Our measurements confirm that M31 satellites obey the same relation between stellar mass and stellar metallicity as Milky Way (MW) satellites and other dwarf galaxies in the Local Group. The metallicity distributions show trends with stellar mass that are similar to those of MW satellites, including evidence in massive satellites for external influence, like pre-enrichment or gas accretion. We present the first measurements of individual element ratios, like [Si/Fe], in the M31 system, as well as measurements of the average [{alpha}/Fe] ratio. The trends of [{alpha}/Fe] with [Fe/H] also follow the same galaxy mass-dependent patterns as MW satellites. Less massive galaxies have more steeply declining slopes of [{alpha}/Fe] that begin at lower [Fe/H]. Finally, we compare the chemical evolution of M31 satellites to M31's Giant Stellar Stream and smooth halo. The properties of the M31 system support the theoretical prediction that the inner halo is composed primarily of massive galaxies that were accreted early. As a result, the inner halo exhibits higher [Fe/H] and [{alpha}/Fe] than surviving satellite galaxies.
- ID:
- ivo://CDS.VizieR/J/ApJ/811/78
- Title:
- Elemental depletions in the Magellanic Clouds
- Short Name:
- J/ApJ/811/78
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a study of the composition of gas and dust in the Large and Small Magellanic Clouds (LMC and SMC) using UV absorption spectroscopy. We measure PII and FeII along 84 spatially distributed sightlines toward the MCs using archival Far Ultraviolet Spectroscopic Explorer observations. For 16 of those sightlines, we also measure SiII, CrII, and ZnII from new Hubble Space Telescope Cosmic Origins Spectrograph observations. We analyze these spectra using a new spectral line analysis technique based on a semi-parametric Voigt profile model. We have combined these measurements with HI and H_2_ column densities and reference stellar abundances from the literature to derive gas-phase abundances, depletions, and gas-to-dust ratios (GDRs). Of our 84 P and 16 Zn measurements, 80 and 13, respectively, are depleted by more than 0.1dex, suggesting that P and Zn abundances are not accurate metallicity indicators at and above the metallicity of the SMC. Si, Cr, and Fe are systematically less depleted in the SMC than in the Milky Way (MW) or LMC. The minimum Si depletion in the SMC is consistent with zero. We find GDR ranges of 190-565 in the LMC and 480-2100 in the SMC, which is broadly consistent with GDRs from the literature. These ranges represent actual location to location variation and are evidence of dust destruction and/or growth in the diffuse neutral phase of the interstellar medium. Where they overlap in metallicity, the gas-phase abundances of the MW, LMC, and SMC and damped Ly{alpha} systems evolve similarly with metallicity.
- ID:
- ivo://CDS.VizieR/J/AZh/73/762
- Title:
- Energy distribution in giants and supergiants.
- Short Name:
- J/AZh/73/762
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The energy distributions for 27 giants and supergiants of the M spectral type are presented in the region of 3200-7600{AA} with the step of 50{AA}. The observations were made in the Fessenkov Astrophysical institute (Alma-Ata) during 1986-1987 with a spectrophotometer of Seya-Namioka mounted on the 50-cm Cassegrain telescope. The primary standard is Vega with the energy distribution by Hayes (1985IAUS..111..225H). The relative r.m.s. of the results are given in the table3.dat.
- ID:
- ivo://CDS.VizieR/J/AZh/77/619
- Title:
- Energy distributions in giants and supergiants
- Short Name:
- J/AZh/77/619
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Normal spectral energy distributions for early-type subgiants, giants and supergiants are derived.
- ID:
- ivo://CDS.VizieR/J/A+A/642/A93
- Title:
- EP Aqr ALMA and SPHERE observations
- Short Name:
- J/A+A/642/A93
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Cool evolved stars are known to be significant contributors to the enrichment of the interstellar medium through their dense and dusty stellar winds. High resolution observations of these outflows have shown them to possess high degrees of morphological complexity. We observed the asymptotic giant branch (AGB) star EP Aquarii with ALMA in band 6 and VLT/SPHERE/ZIMPOL in four filters the visible. Both instruments had an angular resolution of 0.025". These are follow-up observations to the lower-resolution 2016 ALMA analysis of EP Aquarii, which revealed that its wind possesses a nearly face-on, spiral-harbouring equatorial density enhancement, with a nearly pole-on bi-conical outflow. At the base of the spiral, the SiO emission revealed a distinct emission void approximately 0.4" to the west of the continuum brightness peak, which was proposed to be linked to the presence of a companion. The new ALMA data better resolve the inner wind and reveal that its morphology as observed in CO is consistent with hydrodynamical companion-induced perturbations. Assuming that photodissociation by the UV-field of the companion is responsible for the emission void in SiO, we deduced the spectral properties of the tentative companion from the size of the hole. We conclude that the most probable companion candidate is a white dwarf with a mass between 0.65 and 0.8M_{sun}_, though a solar-like companion could not be definitively excluded. The radial SiO emission shows periodic, low-amplitude perturbations. We tentatively propose that they could be the consequence of the interaction of the AGB wind with another much closer low-mass companion. The polarised SPHERE/ZIMPOL data show a circular signal surrounding the AGB star with a radius of ~0.1". Decreased signal along a PA of 138{deg} suggests that the dust is confined to an inclined ring-like structure, consistent with the previously determined wind morphology.
- ID:
- ivo://CDS.VizieR/J/A+A/622/A190
- Title:
- eps Tau intensity and RV time-series data
- Short Name:
- J/A+A/622/A190
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Asteroseismic analysis of solar-like stars allows us to determine physical parameters such as stellar mass, with a higher precision compared to most other methods. Even in a well-studied cluster such as the Hyades, the masses of the red giant stars are not well known, and previous mass estimates are based on model calculations (isochrones). The four known red giants in the Hyades are assumed to be clump (core-helium-burning) stars based on their positions in colour-magnitude diagrams, however asteroseismology offers an opportunity to test this assumption. Using asteroseismic techniques combined with other methods, we aim to derive physical parameters and the evolutionary stage for the planet hosting star epsilon Tau, which is one of the four red giants located in the Hyades. We analysed time-series data from both ground and space to perform the asteroseismic analysis. By combining high signal-to-noise (S/N) radial-velocity data from the ground-based SONG network with continuous space-based data from the revised Kepler mission K2, we derive and characterize 27 individual oscillation modes for epsilon Tau, along with global oscillation parameters such as the large frequency separation {Delta}{nu} and the ratio between the amplitude of the oscillations measured in radial velocity and intensity as a function of frequency. The latter has been measured previously for only two stars, the Sun and Procyon. Combining the seismic analysis with interferometric and spectroscopic measurements, we derive physical parameters for epsilon Tau, and discuss its evolutionary status. Along with other physical parameters, we derive an asteroseismic mass for epsilon Tau of M=2.458+/-0.073M_{sun}_, which is slightly lower than previous estimates, and which leads to a revised minimum mass of the planetary companion. Noting that the SONG and K2 data are non-simultaneous, we estimate the amplitude ratio between intensity and radial velocity to be 42.2+/-2.3ppm m/s, which is higher than expected from scaling relations.
- ID:
- ivo://CDS.VizieR/J/ApJ/638/1018
- Title:
- Equivalent widths for giant stars in M13 and M71
- Short Name:
- J/ApJ/638/1018
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present Mg isotope ratios in four red giants of the globular cluster M13 and one red giant of the globular cluster M71 based on high-resolution, high signal-to-noise ratio spectra obtained with HDS on the Subaru Telescope.
- ID:
- ivo://CDS.VizieR/J/ApJ/760/86
- Title:
- Equivalent widths for 13 NGC2419 RGB stars
- Short Name:
- J/ApJ/760/86
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new Keck/HIRES observations of six red giants in the globular cluster (GC) NGC 2419. Although the cluster is among the most distant and most luminous in the Milky Way, it was considered chemically ordinary until very recently. Our previous work showed that the near-infrared Ca II triplet line strength varied more than expected for a chemically homogeneous cluster, and that at least one star had unusual abundances of Mg and K. Here, we confirm that NGC 2419 harbors a population of stars, comprising about one-third of its mass, that is depleted in Mg by a factor of eight and enhanced in K by a factor of six with respect to the Mg-normal population. Although the majority, Mg-normal population appears to have a chemical abundance pattern indistinguishable from ordinary, inner-halo GCs, the Mg-poor population exhibits dispersions of several elements. The abundances of K and Sc are strongly anti-correlated with Mg, and some other elements (Si and Ca among others) are weakly anti-correlated with Mg. These abundance patterns suggest that the different populations of NGC 2419 sample the ejecta of diverse supernovae in addition to asymptotic giant branch ejecta. However, the abundances of Fe-peak elements except Sc show no star-to-star variation. We find no nucleosynthetic source that satisfactorily explains all of the abundance variations in this cluster. Because NGC 2419 appears like no other GC, we reiterate our previous suggestion that it is not a GC at all, but rather the core of an accreted dwarf galaxy.
