- 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.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/406/987
- Title:
- Elemental abundances of three CP stars
- Short Name:
- J/A+A/406/987
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We used data from the EBASIM spectrograph of the 2.1-m CASLEO telescope to study three rather sharp-lined late B to early A stars {xi} Oct (B6 IV), {alpha} Sex (B9.5 III), and 68 Tau (A2 IV). These measurements are compared with those from the Anglo-Austrialian Telescope for the first star and to those from the coude spectrograph of the 1.22-m telescope of the Dominion Astrophysical Observatory (DAO) for the other two stars. The equivalent width scales of the EBASIM and the DAO data are similar. Thus for the latter two stars the DAO data is also used in the analyses. Both {xi} Oct and {alpha} Sex generally have abundances close to those of the Sun in the range of values found for other normal stars with similar effective temperatures. The abundance pattern for 68 Tau is that of a metallic-lined star as is well known.
- ID:
- ivo://CDS.VizieR/J/MNRAS/460/884
- Title:
- EMBLA survey. Galactic bulge metal-poor stars
- Short Name:
- J/MNRAS/460/884
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Cosmological models predict the oldest stars in the Galaxy should be found closest to the centre of the potential well, in the bulge. The Extremely Metal-poor BuLge stars with AAOmega survey (EMBLA) successfully searched for these old, metal-poor stars by making use of the distinctive SkyMapper photometric filters to discover candidate metal-poor stars in the bulge. Their metal-poor nature was then confirmed using the AAOmega spectrograph on the Anglo-Australian Telescope. Here we present an abundance analysis of 10 bulge stars with -2.8<[Fe/H]<-1.7 from MIKE/Magellan observations, in total determining the abundances of 22 elements. Combining these results with our previous high-resolution data taken as part of the Gaia-ESO Survey, we have started to put together a picture of the chemical and kinematic nature of the most metal-poor stars in the bulge. The currently available kinematic data are consistent with the stars belonging to the bulge, although more accurate measurements are needed to constrain the stars' orbits. The chemistry of these bulge stars deviates from that found in halo stars of the same metallicity. Two notable differences are the absence of carbon-enhanced metal-poor bulge stars, and the {alpha} element abundances exhibit a large intrinsic scatter and include stars which are underabundant in these typically enhanced elements.
- ID:
- ivo://CDS.VizieR/J/MNRAS/421/1043
- Title:
- Emission-line galaxies from SDSS DR7
- Short Name:
- J/MNRAS/421/1043
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a sample of 2865 emission-line galaxies with strong nebular HeII{lambda}4686 emissions in the Sloan Digital Sky Survey Data Release 7 and use this sample to investigate the origin of this line in star-forming galaxies. We show that star-forming galaxies and galaxies dominated by an active galactic nucleus form clearly separated branches in the HeII{lambda}4686/H{beta} versus [NII]{lambda}6584/H{alpha} diagnostic diagram and derive an empirical classification scheme which separates the two classes. We also present an analysis of the physical properties of 189 star-forming galaxies with strong HeII{lambda}4686 emissions. These star-forming galaxies provide constraints on the hard ionizing continuum of massive stars.
- ID:
- ivo://CDS.VizieR/J/AJ/143/145
- Title:
- Emission-line objects from ALFALFA H{alpha} survey
- Short Name:
- J/AJ/143/145
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- During a wide-field narrowband H{alpha} imaging survey, we noted the presence of numerous isolated emission-line point sources in the data. These objects could represent ultra-low-luminosity galaxies at low-redshift (detection via H{alpha}), isolated extragalactic HII regions associated with the galaxy targeted by the original observation, or background galaxies or QSOs where strong emission lines (most often [OIII]{lambda}5007) redshift into our narrowband filter. We have carried out a systematic search for these "H{alpha} dots" in over 200 15x15arcmin fields. To date we have cataloged 61 candidate emission-line sources in roughly 11.7deg^2^. The sample has a median R magnitude of 19.5, and detects objects as faint as R=22.6. Follow-up spectroscopy reveals that ~85% of the candidates are bona fide emission-line objects, with roughly 60% of the real sources being lower-redshift objects (detection via H{alpha}) and 40% being higher-redshift objects detected via [OIII] emission or some other emission line. Here we present the results of our initial survey and follow-up spectroscopy. We use our sample to study the properties (including star-formation rates and metal abundances) of low-luminosity star-forming galaxies in the nearby universe and of low-metallicity star-forming galaxies at z~0.33.
- ID:
- ivo://CDS.VizieR/J/A+A/418/1073
- Title:
- Emission lines in optical spectrum of 3 Cen A
- Short Name:
- J/A+A/418/1073
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Weak emission lines in the optical spectrum of the helium-weak chemically peculiar star 3 Cen A are tabulated. The observed wavelengths, line identification information and equivalent widths are presented based on data obtained with the ESO 1.5m telescope and FEROS instrument (16-17 May 2000) and the VLT with UVES spectrograph (24 June 2001). Table 2 is a listing of all recorded emission lines arranged by wavelength and including unidentified features. Table 3 arranges the identified lines according to their ion and multiplet.
- ID:
- ivo://CDS.VizieR/J/ApJ/659/1265
- Title:
- Emission lines in 4 planetary nebulae
- Short Name:
- J/ApJ/659/1265
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The s-process should occur in all but the lower mass progenitor stars of planetary nebulae, and this should be reflected in the chemical composition of the gas that is expelled to create the current planetary nebula shell. Weak forbidden emission lines are expected from several s-process elements in these shells and have been searched for and in some cases detected in previous investigations. Here we extend these studies by combining very high signal-to-noise ratio echelle spectra of a sample of PNe with a critical analysis of the identification of the emission lines of Z>30 ions. Emission lines of Br, Kr, Xe, Rb, Ba, and Pb are detected with a reasonable degree of certainty in at least some of the objects studied here, and we also tentatively identify lines from Te and I, each in one object. The strengths of these lines indicate enhancement of s-process elements in the central star progenitors, and we determine the abundances of Br, Kr, and Xe, elements for which atomic data relevant for abundance determination have recently become available. As representative elements of the "light" and "heavy" s-process peaks, Kr and Xe exhibit similar enhancements over solar values, suggesting that PN progenitors experience substantial neutron exposure.
- ID:
- ivo://CDS.VizieR/J/ApJ/804/64
- Title:
- Empirical and model parameters of 183 M dwarfs
- Short Name:
- J/ApJ/804/64
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Precise and accurate parameters for late-type (late K and M) dwarf stars are important for characterization of any orbiting planets, but such determinations have been hampered by these stars' complex spectra and dissimilarity to the Sun. We exploit an empirically calibrated method to estimate spectroscopic effective temperature (T_eff_) and the Stefan-Boltzmann law to determine radii of 183 nearby K7-M7 single stars with a precision of 2%-5%. Our improved stellar parameters enable us to develop model-independent relations between T_eff_ or absolute magnitude and radius, as well as between color and T_eff_. The derived T_eff_-radius relation depends strongly on [Fe/H], as predicted by theory. The relation between absolute K_S_magnitude and radius can predict radii accurate to ~=3%. We derive bolometric corrections to the VR_C_I_C_grizJHK_S_ and Gaia passbands as a function of color, accurate to 1%-3%. We confront the reliability of predictions from Dartmouth stellar evolution models using a Markov chain Monte Carlo to find the values of unobservable model parameters (mass, age) that best reproduce the observed effective temperature and bolometric flux while satisfying constraints on distance and metallicity as Bayesian priors. With the inferred masses we derive a semi-empirical mass-absolute magnitude relation with a scatter of 2% in mass. The best-agreement models overpredict stellar T_eff_ values by an average of 2.2% and underpredict stellar radii by 4.6%, similar to differences with values from low-mass eclipsing binaries. These differences are not correlated with metallicity, mass, or indicators of activity, suggesting issues with the underlying model assumptions, e.g., opacities or convective mixing length.
- ID:
- ivo://CDS.VizieR/J/A+AS/139/29
- Title:
- Empirical calibration of the 4000 A break
- Short Name:
- J/A+AS/139/29
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Empirical fitting functions, describing the behaviour of the {lambda}4000{AA} break in terms of effective temperature, metallicity and surface gravity, are presented. For this purpose, the break has been measured in 392 stars from the Lick/IDS Library. We have followed a very detailed error treatment in the reduction and fitting procedures, allowing for a reliable estimation of the break uncertainties. This calibration can be easily incorporated into stellar population models to provide accurate predictions of the break amplitude for, relatively old, composite systems. Table 1 lists the star sample, together with spectral types, adopted atmospheric parameters, break measurements, including errors, and residuals from the fitting functions.
- ID:
- ivo://CDS.VizieR/J/MNRAS/326/959
- Title:
- Empirical calibration of the near-IR Ca triplet
- Short Name:
- J/MNRAS/326/959
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- File table contains details of the new near-IR stellar library observed to calibrate the Ca II triplet. It includes the indices CaT*, CaT and PaT measured over the final spectra as well as their corresponding errors. The Henry Draper Catalogue number, other names (mainly HR and BD numbers), coordinates, spectral type, luminosity class, apparent magnitude and atmospheric parameters (as derived in Paper II; Cenarro et al., 2001MNRAS.326..981C) are also given.