- ID:
- ivo://CDS.VizieR/J/A+A/604/A53
- Title:
- ALLSMOG final data release. A new APEX CO survey
- Short Name:
- J/A+A/604/A53
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the final data release of the APEX low-redshift legacy survey for molecular gas (ALLSMOG), comprising CO(2-1) emission line observations of 88 nearby, low-mass (10^8.5^<M_*_[M_{sun}_]<10^10^) star-forming galaxies carried out with the 230GHz APEX-1 receiver on the APEX telescope. The main goal of ALLSMOG is to probe the molecular gas content of more typical and lower stellar mass galaxies than have been studied by previous CO surveys. We also present IRAM 30m observations of the CO(1-0) and CO(2-1) emission lines in nine galaxies aimed at increasing the M_*_<10^9^M_{sun}_ sample size.In this paper we describe the observations, data reduction and analysis methods and we present the final CO spectra together with archival HI 21cm line observations for the entire sample of 97 galaxies. At the sensitivity limit of ALLSMOG, we register a total CO detection rate of 47%. Galaxies with higher M_*_, SFR, nebular extinction (A_V_), gas-phase metallicity (O/H), and HI gas mass have systematically higher CO detection rates.In particular, the parameter according to which CO detections and non-detections show the strongest statistical differences is the gas-phase metallicity, for any of the five metallicity calibrations examined in this work. We investigate scaling relations between the CO(1-0) line luminosity (L'_CO(1-0)_) and galaxy-averaged properties using ALLSMOG and a sub-sample of COLD GASS for a total of 185 sources that probe the local main sequence (MS) of star-forming galaxies and its +/-0.3dex intrinsic scatter from M_*_=10^8.5^M_{sun}_ to M_*_=10^11^M_{sun}_. L'_CO(1-0)_ is most strongly correlated with the SFR, but the correlation with M_*_ is closer to linear and almost comparably tight. The relation between L'_CO(1-0)_ and metallicity is the steepest one, although deeper CO observations of galaxies with A_V_<0.5mag may reveal an as much steep correlation with A_V_. Our results suggest that star-forming galaxies across more than two orders of magnitude in M_*_ obey similar scaling relations between CO luminosity and the galaxy properties examined in this work. Besides SFR, the CO luminosity is likely most fundamentally linked to M_*_, although we note that stellar mass alone cannot explain all of the variation in CO emission observed as a function of O/H and M_HI_.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/636/A67
- Title:
- ALMA maps of 6 sources of star forming regions
- Short Name:
- J/A+A/636/A67
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- As a building block for amino acids, formamide (NH_2_CHO) is an important molecule in astrobiology and astrochemistry, but its formation path in the interstellar medium is not understood well. We aim to find empirical evidence to support the chemical relationships of formamide to HNCO and H_2_CO. We examine high angular resolution (~0.2") Atacama Large Millimeter/submillimeter Array (ALMA) maps of six sources in three high-mass star-forming regions and compare the spatial extent, integrated emission peak position, and velocity structure of HNCO and H_2_CO line emission with that of NH_2_CHO by using moment maps. Through spectral modeling, we compare the abundances of these three species. In these sources, the emission peak separation and velocity dispersion of formamide emission is most often similar to HNCO emission, while the velocity structure is generally just as similar to H_2_CO and HNCO (within errors). From the spectral modeling, we see that the abundances between all three of our focus species are correlated, and the relationship between NH_2_CHO and HNCO reproduces the previously demonstrated abundance relationship. In this first interferometric study, which compares two potential parent species to NH_2_CHO, we find that all moment maps for HNCO are more similar to NH_2_CHO than H_2_CO in one of our six sources (G24 A1). For the other five sources, the relationship between NH_2_CHO, HNCO, and H_2_CO is unclear as the different moment maps for each source are not consistently more similar to one species as opposed to the other.
- ID:
- ivo://CDS.VizieR/J/A+A/556/L1
- Title:
- ALMA observations of 12CO/13CO around R Scl
- Short Name:
- J/A+A/556/L1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The detached-shell source R Scl, displaying CO emission from recent mass loss, in a binary-induced spiral structure as well as in a clumpy shell produced during a thermal pulse, provides a unique laboratory for studying the differences in CO isotope abundances throughout its recent evolution. We observed both the ^12^CO(J=3-2) and the ^13^CO(J=3-2) line using ALMA. We find significant variations in the ^12^CO/^13^CO intensity ratios and consequently in the abundance ratios. The average CO isotope abundance ratio is at least a factor three lower in the shell (~19) than that in the present-day (<~300yr) mass loss (>60). Additionally, variations in the ratio of more than an order of magnitude are found in the shell itself. We attribute these variations to the competition between selective dissociation and isotope fractionation in the shell, of which large parts cannot be warmer than ~35K. However, we also find that the ^12^CO/^13^CO ratio in the present-day mass loss is significantly higher than the ^12^C/^13^C ratio determined in the stellar photosphere from molecular tracers (~19). The origin of this discrepancy is still unclear, but we speculate that it is due to an embedded source of UV-radiation that is primarily photo-dissociating ^13^CO. This radiation source could be the hitherto hidden companion. Alternatively, the UV-radiation could originate from an active chromosphere of R Scl itself. Our results indicate that caution should be taken when directly relating the ^12^CO/^13^CO intensity and ^12^C/^13^C abundance ratios for specific asymptotic giant branch stars, in particular binaries or stars that display signs of chromospheric stellar activity.
- ID:
- ivo://CDS.VizieR/J/ApJ/711/619
- Title:
- {alpha}-element abundances in galactic PNe
- Short Name:
- J/ApJ/711/619
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this paper, we present emission line strengths, abundances, and element ratios (X/O for Ne, S, Cl, and Ar) for a sample of 38 Galactic disk planetary nebulae (PNe) consisting primarily of Peimbert classification Type I. Spectrophotometry for these PNe incorporates an extended optical/near-IR range of 3600-9600{AA} including the [SIII] lines at 9069{AA} and 9532{AA}, setting this relatively large sample apart from typical spectral coverage. We have utilized Emission Line Spectrum Analyzer, a five-level atom abundance routine, to determine Te, Ne, ionization correction factors, and total element abundances, thereby continuing our work toward a uniformly processed set of data. With a compilation of data from >120 Milky Way PNe, we present results from our most recent analysis of abundance patterns in Galactic disk PNe. With a wide range of metallicities, galactocentric distances, and both Type I and non-Type I objects, we have examined the alpha elements against HII regions and blue compact galaxies (H2BCGs) to discern signatures of depletion or enhancement in PNe progenitor stars, particularly the destruction or production of O and Ne.
- ID:
- ivo://CDS.VizieR/J/A+A/580/A17
- Title:
- {alpha}-element abundances of Cepheid stars
- Short Name:
- J/A+A/580/A17
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new homogeneous measurements of Na, Al, and three alpha-elements (Mg, Si, Ca) for 75 Galactic Cepheids, complemented with Cepheid abundances available in the literature, for a total of 439 stars. The abundances are based on high spectral resolution (R~38000) and high signal-to-noise ratio (S/N~50-300) spectra collected with UVES at ESO VLT. Special attention was given to providing a homogeneous abundance scale for these five elements plus iron. In addition, accurate Galactocentric distances (RG) based on near-infrared photometry are also available for all the Cepheids in the sample. We found that these five elements display well-defined linear radial gradients and modest standard deviations over the entire range of RG. The [element/Fe] abundance ratios are constant across the entire thin disk and over the entire period range; only the Ca radial distribution shows marginal evidence of slopes. These results indicate that the chemical enrichment history of iron and of the quoted elements has been quite similar across the four quadrants of the Galactic thin disk, and very homogenous within the range in age covered by the Cepheids (~10-300Myr). Finally, we also find that Cepheid abundances agree with similar abundances for thin and thick disk dwarf stars, and they follow the typical Mg-Al and Na-O correlations.
- ID:
- ivo://CDS.VizieR/J/ApJ/883/128
- Title:
- alpha & Fe abundances in the giant stellar stream
- Short Name:
- J/ApJ/883/128
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first measurements of [Fe/H] and [{alpha}/Fe] abundances, obtained using spectral synthesis modeling, for red giant branch stars in M31's giant stellar stream (GSS). The spectroscopic observations, obtained at a projected distance of 17kpc from M31's center, yielded 61 stars with [Fe/H] measurements, including 21 stars with [{alpha}/Fe] measurements, from 112 targets identified as M31 stars. The [Fe/H] measurements confirm the expectation from photometric metallicity estimates that stars in this region of M31's halo are relatively metal rich compared to stars in the Milky Way's inner halo: more than half the stars in the field, including those not associated with kinematically identified substructure, have [Fe/H] abundances >-1.0. The stars in this field are {alpha}-enhanced at lower metallicities, while [{alpha}/Fe] decreases with increasing [Fe/H] above metallicities of [Fe/H]>~-0.9. Three kinematical components have been previously identified in this field: the GSS, a second kinematically cold feature of unknown origin, and M31's kinematically hot halo. We compare probabilistic [Fe/H] and [{alpha}/Fe] distribution functions for each of the components. The GSS and the second kinematically cold feature have very similar abundance distributions, while the halo component is more metal poor. Although the current sample sizes are small, a comparison of the abundances of stars in the GSS field with abundances of M31 halo and dSph stars from the literature indicate that the progenitor of the stream was likely more massive, and experienced a higher efficiency of star formation, than M31's existing dSphs or the dEs NGC147 and NGC185.
- ID:
- ivo://CDS.VizieR/J/other/RAA/16.G10
- Title:
- [alpha/Fe] ratios from LAMOST spectra
- Short Name:
- J/other/RAA/16.G
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The [{alpha}/Fe] ratios in stars are good tracers to probe the formation history of stellar populations and the chemical evolution of the Galaxy. The spectroscopic survey of LAMOST provides a good opportunity to determine [{alpha}/Fe] of millions of stars in the Galaxy. We present a method of measuring the [{alpha}/Fe] ratios from LAMOST spectra using the template-matching technique of the LSP3 pipeline. We use three test samples of stars selected from the ELODIE and MILES libraries, as well as the LEGUE survey to validate our method. Based on the test results, we conclude that our method is valid for measuring [{alpha}/Fe] from low-resolution spectra acquired by the LAMOST survey. Within the range of the stellar parameters Teff=[5000, 7500]K, logg=[1.0, 5.0]dex and [Fe/H]=[-1.5, +0.5]dex, our [{alpha}/Fe] measurements are consistent with values derived from high-resolution spectra, and the accuracy of our [{alpha}/Fe] measurements from LAMOST spectra is better than 0.1dex with spectral signal-to-noise higher than 20.
- ID:
- ivo://CDS.VizieR/J/ApJ/708/1290
- Title:
- A 2MASS view of the Sgr dSph. VI.
- Short Name:
- J/ApJ/708/1290
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present high-resolution spectroscopic measurements of the abundances of the {alpha} element titanium (Ti) and s-process elements yttrium (Y) and lanthanum (La) for 59 candidate M giant members of the Sagittarius (Sgr) dwarf spheroidal (dSph) + tidal tail system pre-selected on the basis of position and radial velocity (RV). As expected, the majority of these stars show peculiar abundance patterns compared to those of nominal Milky Way (MW) stars, but as a group, the stars form a coherent picture of chemical enrichment of the Sgr dSph from [Fe/H]=-1.4 to solar abundance. Finally, we analyze the chemical abundances of a moving group of M giants among the Sgr leading arm stars at the North Galactic Cap, but having RVs unlike the infalling Sgr leading arm debris there. Through use of "chemical fingerprinting," we conclude that these mostly receding northern hemisphere M giants also are Sgr stars, likely trailing arm debris overlapping the Sgr leading arm in the north.
- ID:
- ivo://CDS.VizieR/J/A+A/647/A162
- Title:
- AMBRE catalogue of sulfur abundances
- Short Name:
- J/A+A/647/A162
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Sulfur is a volatile chemical element that plays an important role in tracing the chemical evolution of the Milky Way and external galaxies. However, its nucleosynthesis origin and abundance variations in the Galaxy are still unclear because the number of available stellar sulfur abundance measurements is currently rather small. The goal of the present article is to accurately and precisely study the sulfur content of large number of stars located in the solar neighbourhood. We use the parametrisation of thousands of high-resolution stellar spectra provided by the AMBRE Project, and combine it with the automated abundance determination GAUGUIN to derive local thermodynamic equilibrium (LTE) sulfur abundances for 1855 slow-rotating FGK-type stars. This is the largest and most precise catalogue of sulfur abundances published to date. It covers a metallicity domain as high as ~2.5dex starting at [M/H]<~-2.0dex. We find that the sulfur-to-iron abundances ratio is compatible with a plateau-like distribution in the metal-poor regime, and then starts to decrease continuously at [M/H]~-1.0dex. This decrease continues towards negative values for supersolar metallicity stars as recently reported for magnesium and as predicted by Galactic chemical evolution models. Moreover, sulfur-rich stars having metallicities in the range [-1.0,-0.5] have very different kinematical and orbital properties with respect to more metal-rich and sulfur-poor ones. Two disc components, associated with the thin and thick discs, are thus seen independently in kinematics and sulfur abundances. The sulfur radial gradients in the Galactic discs have also been estimated. Finally, the enrichment in sulfur with respect to iron is nicely correlated with stellar ages: older metal-poor stars have higher [S/M] ratios than younger metal-rich ones. This work has confirmed that sulfur is an {alpha}-element that could be considered to explore the Galactic populations properties. For the first time, a chemo-dynamical study from the sulfur abundance point of view, as a stand-alone chemical element, is performed.
- ID:
- ivo://CDS.VizieR/J/A+A/542/A48
- Title:
- AMBRE project. FEROS archived spectra
- Short Name:
- J/A+A/542/A48
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The AMBRE Project is a collaboration between the European Southern Observatory (ESO) and the Observatoire de la Cote d'Azur (OCA) that has been established in order to carry out the determination of stellar atmospheric parameters for the archived spectra of four ESO spectrographs. The analysis of the FEROS archived spectra for their stellar parameters (effective temperatures, surface gravities, global metallicities, alpha element to iron ratios and radial velocities) has been completed in the first phase of the AMBRE Project. From the complete ESO:FEROS archive dataset that was received, a total of 21551 scientific spectra have been identified, covering the period 2005 to 2010. These spectra correspond to 6285 stars. The determination of the stellar parameters was carried out using the stellar parameterisation algorithm, MATISSE (MATrix Inversion for Spectral SynthEsis), which has been developed at OCA to be used in the analysis of large scale spectroscopic studies in galactic archaeology. An analysis pipeline has been constructed that integrates spectral normalisation, cleaning and radial velocity correction procedures in order that the FEROS spectra could be analysed automatically with MATISSE to obtain the stellar parameters. The synthetic grid against which the MATISSE analysis is carried out is currently constrained to parameters of FGKM stars only. Stellar atmospheric parameters, effective temperature, surface gravity, metallicity and alpha element abundances, were determined for 6508 (30.2%) of the FEROS archived spectra (~3087 stars). Radial velocities were determined for 11963 (56%) of the archived spectra. 2370 (11%) spectra could not be analysed within the pipeline due to very low signal-to-noise ratios or missing spectral orders. 12673 spectra (58.8%) were analysed in the pipeline but their parameters were discarded based on quality criteria and error analysis determined within the automated process. The majority of these rejected spectra were found to have broad spectral features, as probed both by the direct measurement of the features and cross-correlation function breadths, indicating that they may be hot and/or fast rotating stars, which are not considered within the adopted reference synthetic spectra grid. The current configuration of the synthetic spectra grid is devoted to slow-rotating FGKM stars. Hence non-standard spectra (binaries, chemically peculiar stars etc.) that could not be identified may pollute the analysis.
