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- ID:
- ivo://CDS.VizieR/J/ApJS/220/16
- Title:
- SpeX NIR survey of 886 nearby M dwarfs
- Short Name:
- J/ApJS/220/16
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalog of near-infrared (NIR) spectra and associated measurements for 886 nearby M dwarfs. The spectra were obtained with the NASA-Infrared Telescope Facility SpeX Spectrograph during a two-year observing campaign; they have high signal-to-noise ratios (S/N>100-150), span 0.8-2.4{mu}m, and have R~2000. Our catalog of measured values contains useful T_eff_ and composition-sensitive features, empirical stellar parameter measurements, and kinematic, photometric, and astrometric properties compiled from the literature. We focus on measurements of M dwarf abundances ([Fe/H] and [M/H]), capitalizing on the precision of recently published empirical NIR spectroscopic calibrations. We explore systematic differences between different abundance calibrations, and from other similar M dwarf catalogs. We confirm that the M dwarf abundances we measure show the expected inverse dependence with kinematic-, activity-, and color-based age indicators. Finally, we provide updated [Fe/H] and [M/H] for 16 M dwarf planet hosts. This catalog represents the largest published compilation of NIR spectra and associated parameters for M dwarfs. It provides a rich and uniform resource for nearby M dwarfs, and will be especially valuable for measuring Habitable Zone locations and comparative abundances of the M dwarf planet hosts that will be uncovered by upcoming exoplanet surveys.
- ID:
- ivo://CDS.VizieR/J/ApJ/736/133
- Title:
- Spitzer-IRS study of massive YSOs in galactic center
- Short Name:
- J/ApJ/736/133
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results from our spectroscopic study, using the Infrared Spectrograph (IRS) on board the Spitzer Space Telescope, designed to identify massive young stellar objects (YSOs) in the Galactic center (GC). Our sample of 107 YSO candidates was selected based on Infrared Array Camera (IRAC) colors from the high spatial resolution, high sensitivity Spitzer/IRAC images in the Central Molecular Zone, which spans the central ~300pc region of the Milky Way. We obtained IRS spectra over 5-35um using both high- and low-resolution IRS modules. We spectroscopically identify massive YSOs by the presence of a 15.4um shoulder on the absorption profile of 15um CO_2_ ice, suggestive of CO_2_ ice mixed with CH_3_OH ice on grains. This 15.4um shoulder is clearly observed in 16 sources and possibly observed in an additional 19 sources. We show that nine massive YSOs also reveal molecular gas-phase absorption from CO_2_, C_2_H_2_, and/or HCN, which traces warm and dense gas in YSOs. Our results provide the first spectroscopic census of the massive YSO population in the GC. We fit YSO models to the observed spectral energy distributions and find YSO masses of 8-23M_{sun}_, which generally agree with the masses derived from observed radio continuum emission. We find that about 50% of photometrically identified YSOs are confirmed with our spectroscopic study. This implies a preliminary star formation rate of ~0.07M_{sun}/yr at the GC.
- ID:
- ivo://CDS.VizieR/J/MNRAS/418/284
- Title:
- s-process in low-metallicity stars. II.
- Short Name:
- J/MNRAS/418/284
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- High-resolution spectroscopic observations of 100 metal-poor carbon and s-rich stars (CEMP-s) collected from the literature are compared with the theoretical nucleosynthesis models of the asymptotic giant branch (AGB) presented in Paper I, Cat. J/MNRAS/404/1529.
- ID:
- ivo://CDS.VizieR/J/ApJ/765/140
- Title:
- Stacked spectra of SDSS star forming galaxies
- Short Name:
- J/ApJ/765/140
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The relation between galaxy stellar mass and gas-phase metallicity is a sensitive diagnostic of the main processes that drive galaxy evolution, namely cosmological gas inflow, metal production in stars, and gas outflow via galactic winds. We employed the direct method to measure the metallicities of ~200000 star-forming galaxies from the Sloan Digital Sky Survey that were stacked in bins of (1) stellar mass and (2) both stellar mass and star formation rate (SFR) to significantly enhance the signal-to-noise ratio of the weak [OIII]{lambda}4363 and [OII]{lambda}{lambda}7320,7330 auroral lines required to apply the direct method. These metallicity measurements span three decades in stellar mass from log(M_*_/M_{sun}_)=7.4-10.5, which allows the direct method mass-metallicity relation to simultaneously capture the high-mass turnover and extend a full decade lower in mass than previous studies that employed more uncertain strong line methods. The direct method mass-metallicity relation rises steeply at low mass (O/H{prop.to}M_*_^1/2^) until it turns over at log(M_*_/M_{sun}_)=8.9 and asymptotes to 12+log(O/H)=8.8 at high mass. The direct method mass-metallicity relation has a steeper slope, a lower turnover mass, and a factor of two to three greater dependence on SFR than strong line mass-metallicity relations. Furthermore, the SFR-dependence appears monotonic with stellar mass, unlike strong line mass-metallicity relations. We also measure the N/O abundance ratio, an important tracer of star formation history, and find the clear signature of primary and secondary nitrogen enrichment. N/O correlates tightly with oxygen abundance, and even more so with stellar mass.
- ID:
- ivo://CDS.VizieR/J/AJ/153/96
- Title:
- Standard Galactic field RR Lyrae. I. Photometry
- Short Name:
- J/AJ/153/96
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a multi-wavelength compilation of new and previously published photometry for 55 Galactic field RR Lyrae variables. Individual studies, spanning a time baseline of up to 30 years, are self-consistently phased to produce light curves in 10 photometric bands covering the wavelength range from 0.4 to 4.5 microns. Data smoothing via the GLOESS technique is described and applied to generate high-fidelity light curves, from which mean magnitudes, amplitudes, rise times, and times of minimum and maximum light are derived. 60000 observations were acquired using the new robotic Three-hundred MilliMeter Telescope (TMMT), which was first deployed at the Carnegie Observatories in Pasadena, CA, and is now permanently installed and operating at Las Campanas Observatory in Chile. We provide a full description of the TMMT hardware, software, and data reduction pipeline. Archival photometry contributed approximately 31000 observations. Photometric data are given in the standard Johnson UBV, Kron-Cousins R_C_I_C_, 2MASS JHK, and Spitzer [3.6] and [4.5] bandpasses.
- ID:
- ivo://CDS.VizieR/J/AJ/141/61
- Title:
- Star clusters in M31. II.
- Short Name:
- J/AJ/141/61
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new high signal-to-noise spectroscopic data on the M31 globular cluster (GC) system, obtained with the Hectospec multifiber spectrograph on the 6.5m MMT. More than 300 clusters have been observed at a resolution of 5{AA} and with a median S/N of 75 per{AA}, providing velocities with a median uncertainty of 6km/s. The primary focus of this paper is the determination of mean cluster metallicities, ages, and reddenings. Metallicities were estimated using a calibration of Lick indices with [Fe/H] provided by Galactic GCs.
- ID:
- ivo://CDS.VizieR/J/ApJ/824/42
- Title:
- Star clusters in M31. VII. Globular clusters RVs
- Short Name:
- J/ApJ/824/42
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We carry out a joint spatial-kinematical-metallicity analysis of globular clusters (GCs) around the Andromeda Galaxy (M31), using a homogeneous, high-quality spectroscopic data set. In particular, we remove the contaminating young clusters that have plagued many previous analyses. We find that the clusters can be divided into three major metallicity groups based on their radial distributions: (1) an inner metal-rich group ([Fe/H]>-0.4); (2) a group with intermediate metallicity (with median [Fe/H]=-1); and (3) a metal-poor group, with [Fe/H]. The metal-rich group has kinematics and spatial properties like those of the disk of M31, while the two more metal-poor groups show mild prograde rotation overall, with larger dispersions --in contrast to previous claims of stronger rotation. The metal-poor GCs are the least concentrated group; such clusters occur five times less frequently in the central bulge than do clusters of higher metallicity. Despite some well-known differences between the M31 and Milky Way GC systems, our revised analysis points to remarkable similarities in their chemodynamical properties, which could help elucidate the different formation stages of galaxies and their GCs. In particular, the M31 results motivate further exploration of a metal-rich GC formation mode in situ, within high-redshift, clumpy galactic disks.
- ID:
- ivo://CDS.VizieR/J/AJ/127/2002
- Title:
- Star Formation Rate of NFGS galaxies
- Short Name:
- J/AJ/127/2002
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate the [O II] emission line as a star formation rate (SFR) indicator using integrated spectra of 97 galaxies from the Nearby Field Galaxies Survey (NFGS). The sample includes all Hubble types and contains SFRs ranging from 0.01 to 100M_{sun}_/yr.
- ID:
- ivo://CDS.VizieR/J/A+A/601/A95
- Title:
- Star-forming dwarfs at intermediate-z in VUDS
- Short Name:
- J/A+A/601/A95
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present emission line measurements and the main physical properties of a sample of 164 star-forming dwarf galaxies (SFDGs) in the VIMOS Ultra Deep Survey (VUDS, Le Fevre et al., 2015A&A...576A..79L). VUDS is one of the largest programs on the ESO-VLT with 640 hours of observing time, and covers a total of one square degree in three separate fields: COSMOS, ECDFS, and VVDS-02h. The spectroscopic observations were carried out at the VLT with the VIMOS Multi-Object Spectrograph (MOS) with two grisms (LRBLUE and LRRED) covering a wavelength range of 365<lambda<935nm at uniform spectral resolution of R=180 and R=210, respectively. The integration time (on-source) is ~14-hours per target for each grism, which allows to detect the continuum at 850nm for i_AB_=25, and emission lines with an observed flux limit F=1.5*10^-18^erg/s/cm2 at S/N~5. Redshift measurements in VUDS were performed using the EZ code (Garilli et al., 2010PASP..122..827G), both in automatic and manual modes (by two persons independently) for each spectrum. The overall redshift accuracy is dz/(1+z)=0.0005-0.0007. The spectra had already been fully calibrated in wavelength and flux by the VUDS team, which also did the sky subtraction. Emission lines fluxes and equivalent widths are measured manually on a one-by- one basis using the task 'splot' of IRAF by direct integration of the line profile after linear subtraction of the continuum. These fluxes are given in units of 10^-18^erg/s/cm^2^. The uncertainties in the line measurements were computed from the dispersion of values provided by multiple measurements adopting different possible band-passes (free of lines and strong residuals from sky subtraction) for the local continuum determination, which is fitted using a second order polynomial. No extinction correction has been applied to these fluxes. The EW measurements of H{gamma}, H{beta} and H{alpha} lines have been already corrected for absorption by +0.1nm for all galaxies, following Ly et al. (2014ApJ...780..122L). For each galaxy the reddening constant, c(H{beta}), is presented. These values and their uncertainties have been derived from the H{alpha}/H{beta} or H{gamma}/H{beta} ratios, whenever possible. We adopted the reddening constant from the best-fit SED, using the relations of Calzetti et al. (2000ApJ...533..682C), for (a) galaxies where the computation of c(H{beta}) from emission lines is not possible because the lines are not present, or (b) the line ratios give a negative extinction correction (i.e., H{alpha}/H{beta}<2.82 or H{gamma}/H{beta}<0.47, assuming Case B recombination with Te=2*10^4^K, ne=100cm^-3^).