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2691. Ssynthetic spectra of supernovae models
ID:
ivo://CDS.VizieR/J/A+A/621/A109
Title:
Ssynthetic spectra of supernovae models
Short Name:
J/A+A/621/A109
Date:
21 Oct 2021
Publisher:
CDS
Description:
Observational surveys are now able to detect an increasing number of transients, such as core-collapse supernovae (SN) and powerful non-terminal outbursts (SN impostors). Dedicated spectroscopic facilities can follow up these events shortly after detection. Here we investigate the properties of these explosions at early times.We use the radiative transfer code CMFGEN to build an extensive library of spectra simulating the interaction of supernovae and their progenitor's winds/circumstellar medium (CSM).We consider a range of progenitor mass-loss rates (dM/dt=5x10^-4^ to 10^-2^ M_{sun}/yr), abundances (solar, CNO-processed, and He-rich), and SN luminosities (L=1.9x10^8^ to 2.5x10^10^L_{sun}_). The models simulate events ~=1-day after explosion, and we assume a fixed location of the shock front as R_in_=8.6x10^13^cm. We show that the large range of massive star properties at the pre-SN stage causes a diversity of early-time interacting SN and impostors. We identify three main classes of early-time spectra consisting of relatively high-ionisation (e.g. HeII and OVI), medium-ionisation (e.g. CIII and NIII), and low-ionisation lines (e.g. HeI and FeII/III). They are regulated by L and the CSM density. Given a progenitor wind velocity v_inf_, our models also place a lower limit of dM/dt>~5x10^-4^(v_inf_=150km/s)M_{sun}_/yr for detection of CSM interaction signatures in observed spectra. Early-time SN spectra should provide clear constraints on progenitors by measuring H, He, and CNO abundances if the progenitors come from single stars. The connections are less clear considering the effects of binary evolution. Nevertheless, our models provide a clear path for linking the final stages of massive stars to their post-explosion spectra at early times, and guiding future observational follow-up of transients with facilities such as the Zwicky Transient Facility.
2692. Stacked spectra of SDSS star forming galaxies
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.
2693. Standard calibration stars infrared spectra
ID:
ivo://CDS.VizieR/J/AJ/132/1445
Title:
Standard calibration stars infrared spectra
Short Name:
J/AJ/132/1445
Date:
21 Oct 2021
Publisher:
CDS
Description:
Infrared spectra with increased spectral resolution and accuracy of the absolute infrared spectral flux have been created for a subset of stellar standards created by Cohen and his collaborators in previous papers in this series. Moderate-resolution ({lambda}/{Delta}{lambda}~400) spectroscopy obtained on infrared standard stars by the Short Wavelength Spectrometer on the Infrared Space Observatory was combined with high-quality photometry tied to our recent absolute calibration from the Midcourse Space Experiment. Thus, 1-35 micron spectra were created for 33 stars, 9 of which are Cohen et al. secondary standards and another 20 of which are tertiary standards for which Cohen adopted spectral templates. The wavelength spacing is given by (0.0001/1 micron)*lambda^2, which provides for 10,000 samples over the 1-35 micron spectral range
2694. Star beyond the NLTT catalog
ID:
ivo://CDS.VizieR/J/AJ/133/2825
Title:
Star beyond the NLTT catalog
Short Name:
J/AJ/133/2825
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have combined near-infrared data from the Two Micron All Sky Survey with ancillary optical data to identify previously unrecognized proper-motion stars that have colors and magnitudes consistent with nearby M dwarfs. We present follow-up observations of 392 stars from that sample, including ~200 stars discussed here for the first time. Our distance estimates, based primarily on spectroscopic parallaxes, place 123 stars within 20pc of the Sun. One hundred and seventy-six stars exhibit H{alpha} emission, and 82 stars have plausible X-ray counterparts from ROSAT observations.
2695. Starbursts luminosities based on PAH
ID:
ivo://CDS.VizieR/J/ApJ/686/127
Title:
Starbursts luminosities based on PAH
Short Name:
J/ApJ/686/127
Date:
21 Oct 2021
Publisher:
CDS
Description:
A summary of starburst luminosities based on polycyclic aromatic hydrocarbon (PAH) features is given for 243 starburst galaxies with 0<z<2.5, observed with the Spitzer Infrared Spectrograph. Luminosity {nu}L_{nu}_(7.7um) for the peak luminosity of the 7.7um PAH emission feature is found to scale as log[{nu}L_{nu}_(7.7{mu}m)]=44.63(+/-0.09)+2.48(+/-0.28)log(1+z) for the most luminous starbursts observed. Empirical calibrations of {nu}L_{nu}_(7.7um) are used to determine bolometric luminosity L_IR_ and the star formation rate (SFR) for these starbursts. The most luminous starbursts found in this sample have logL_IR_=45.4(+/-0.3)+2.5(+/-0.3)log(1+z), in ergs/s, and the maximum star formation rates for starbursts in units of M_{sun}_/yr are log(SFR)=2.1(+/-0.3)+2.5(+/-0.3)log(1+z), up to z=2.5. The exponent for pure luminosity evolution agrees with optical and radio studies of starbursts but is flatter than previous results based in infrared source counts. The maximum star formation rates are similar to the maxima determined for submillimeter galaxies; the most luminous individual starburst included within the sample has logL_IR_=46.9, which gives an SFR=3.4x10^3^M_{sun}/yr. Description: In this paper, we assemble data from 14 different Spitzer/IRS (InfraRed Spectrograph) programs (listed in "Ref" column of table1) to summarize a wide variety of sources having strong PAH spectral features, providing a total of 243 sources.
2696. StarCAT: STIS UV echelle spectra of stars
ID:
ivo://CDS.VizieR/J/ApJS/187/149
Title:
StarCAT: STIS UV echelle spectra of stars
Short Name:
J/ApJS/187/149
Date:
21 Oct 2021
Publisher:
CDS
Description:
StarCAT is a catalog of high resolution ultraviolet spectra of objects classified as "stars," recorded by Space Telescope Imaging Spectrograph (STIS) during its initial seven years of operations (1997-2004). StarCAT is based on 3184 echelle observations of 545 distinct targets, with a total exposure duration of 5.2Ms. For many of the objects, broad ultraviolet coverage has been achieved by splicing echellegrams taken in two or more FUV (1150-1700{AA}) and/or NUV (1600-3100{AA}) settings. In cases of multiple pointings on conspicuously variable sources, spectra were separated into independent epochs. Otherwise, different epochs were combined to enhance the signal-to-noise ratio (S/N). A post-facto correction to the "calstis" pipeline data sets compensated for subtle wavelength distortions identified in a previous study of the STIS calibration lamps. An internal "fluxing" procedure yielded coherent spectral energy distributions (SEDs) for objects with broadly overlapping wavelength coverage. The best StarCAT material achieves 300m/s internal velocity precision; absolute accuracy at the 1km/s level; photometric accuracy of order 4%; and relative flux precision several times better (limited mainly by knowledge of SEDs of UV standard stars). While StarCAT represents a milestone in the large-scale post-processing of STIS echellegrams, a number of potential improvements in the underlying "final" pipeline are identified.
2697. Star cluster Gaia 1 stars equivalent widths
ID:
ivo://CDS.VizieR/J/A+A/609/A13
Title:
Star cluster Gaia 1 stars equivalent widths
Short Name:
J/A+A/609/A13
Date:
21 Oct 2021
Publisher:
CDS
Description:
Star clusters, particularly those objects in the disk-bulge-halo interface are as yet poorly charted, despite the fact that they carry important information about the formation and the structure of the Milky Way. Here, we present a detailed chemical abundance study of the recently discovered object Gaia 1. Photometry has previously suggested it as an intermediate-age, moderately metal-rich system, although the exact values for its age and metallicity remained ambiguous in the literature. We measured detailed chemical abundances of 14 elements in four red giant members, from high-resolution (R=25000) spectra that firmly establish Gaia 1 as an object associated with the thick disk. The resulting mean Fe abundance is -0.62+/-0.03(stat.)+/-0.10(sys.) dex, which is more metal-poor than indicated by previous spectroscopy from the literature, but it is fully in line with values from isochrone fitting. We find that Gaia 1 is moderately enhanced in the {alpha}-elements, which allowed us to consolidate its membership with the thick disk via chemical tagging. The cluster's Fe-peak and neutron-capture elements are similar to those found across the metal-rich disks, where the latter indicate some level of s-process activity. No significant spread in iron nor in other heavy elements was detected, whereas we find evidence of light-element variations in Na, Mg, and Al. Nonetheless, the traditional Na-O and Mg-Al (anti-)correlations, typically seen in old globular clusters, are not seen in our data. This confirms that Gaia 1 is rather a massive and luminous open cluster than a low-mass globular cluster. Finally, orbital computations of the target stars bolster our chemical findings of Gaia 1's present-day membership with the thick disk, even though it remains unclear which mechanisms put it in that place.
2698. Star formation activities in MaNGA low-mass galaxies
ID:
ivo://CDS.VizieR/J/ApJ/894/57
Title:
Star formation activities in MaNGA low-mass galaxies
Short Name:
J/ApJ/894/57
Date:
03 Dec 2021 00:39:35
Publisher:
CDS
Description:
We explore the environmental influences on the star formation (SF) in low-mass galaxies with stellar mass 8<=log(M_*_/M_{sun}_)<=10 at a redshift of 0.01<z<0.07. We identify the neighboring galaxies for our sample using the spectroscopically observed galaxies in the Sloan Digital Sky Survey (SDSS). Our 287 selected pair candidates have a neighboring galaxy with a stellar mass ratio of M_Neighbor_/M_Candidate_<=4 at a projected separation within d_proj_<=1500kpc and a line-of-sight kinematic separation of {Delta}v_LOS_<=300km/s. Our control galaxies are isolated from other galaxies within a projected radius of 1500kpc. All selected galaxies in our sample are spectroscopically observed by the fourth generation of SDSS/Mapping Nearby Galaxies at Apache Point Observatory (SDSS-IV/MaNGA) integral field spectroscopy survey. We radially bin our selected galaxies into three regions with a radial distance of 0<=R/R_e_<=0.5 (inner), 0.5<=R/R_e_<=1.0 (middle), and 1.0<=R/R_e_<=1.5 (outer), in which R_e_ is the effective radius at where the galaxy emit half of its light. We conclude that the SF activities in low-mass galaxies are affected by their environmental conditions when {Delta}v_LOS_<=100km/s at d_proj_<=400kpc. We use stellar-mass-weighted SF rate surface density ({Sigma}SFR/M_*_) to describe the SF strength in each radially binned region. For the pair candidates with 0.25<=M_Neighbor_/M_Candidate_<=4 at d_proj_<=100kpc and {Delta}v_LOS_<=100km/s, we observe an SF enhancement of f_{Delta}SF_=1.75+/-0.96 (f_{Delta}SF_=[({Sigma}SFR/M_*_)_Pair_-({Sigma}SFR/M_*_)_Control,mean_] /({Sigma}SFR/M_*_)_Control,mean_) in their inner regions, which decreases with increasing galactic radii.
2699. Star Formation in Early-type galaxies
ID:
ivo://CDS.VizieR/J/A+AS/130/251
Title:
Star Formation in Early-type galaxies
Short Name:
J/A+AS/130/251
Date:
21 Oct 2021
Publisher:
CDS
Description:
The paper is the first of a series (Longhetti et al., 1998A&AS..130..267L, 1998b (Paper III) in press) dedicated to the study of the star formation history in early-type galaxies which show fine structures and/or interaction signatures. It presents nuclear line-strength indices for a sample composed of 21 shell galaxies, from the Malin & Carter (1983ApJ...274..534M) southern survey, and 30 members of isolated interacting pairs, from the Reduzzi & Rampazzo (1995ApL....30....1R) catalogue, located in low density environments. The spectral range covers 3700{AA}<{lambda}<5700{AA} at 2.1{AA}FWHM resolution. We measure 16 red ({lambda}>4200{AA}) indices defined by the Lick Group. Measures have been transformed into the Lick-IDS ``standard'' system. The procedure has been tested on a set of 5 elliptical galaxies selected from the Gonzalez (1993, Ph.D. thesis) sample. We derive also three blue ({lambda}<4200) indices, namely {DELTA}(4000{AA}) defined by Hamilton (1985ApJ...297..371H), H+K(CaII) and Hdelta/FeI defined by Rose (1984AJ.....89.1238R, 1985AJ.....90.1927R). Blue indices are correlated to the age of the last starburst occurred in a galaxy (Leonardi & Rose, 1996AJ....111..182L). The indices determination, the estimate of the measurement errors and the correction for the galaxies velocity dispersions are discussed in detail. In the Appendix A we present the indices for a set of hot stars (T>10000K) which may be used for extending, toward high temperatures, Worthey (1992, Ph.D. Thesis) fitting functions.
2700. Star formation in early-type galaxies
ID:
ivo://CDS.VizieR/J/A+A/345/419
Title:
Star formation in early-type galaxies
Short Name:
J/A+A/345/419
Date:
21 Oct 2021
Publisher:
CDS
Description:
We analyze the star formation properties of a sample of 21 shell galaxies and 30 early-type galaxies members of interacting pairs, located in low density environments (Longhetti et al., 1998, Cat. <J/A+AS/130/251>, 1998A&AS..130..267L). The study is based on new models developed to interpret the information coming from `blue' H{delta}FeI, H+K(CaII) and D4000 line-strength indices proposed by Rose (1984AJ.....89.1238R; 1985AJ.....90.1927R) and Hamilton (1985ApJ...297..371H). We find that the last star forming event that occurred in the nuclear region of shell galaxies is statistically old (from 0.1 up to several Gyr) with respect to the corresponding one in the sub-sample of pair galaxies (<0.1Gyr or even ongoing star formation). If the stellar activity is somehow related to the formation of shells, as predicted by several dynamical models of galaxy interaction, shells have to be considered long lasting structures. Since pair members show evidence of very recent star formation, we suggest that either large reservoirs of gas have to be present to maintain active star formation, if these galaxies are on periodic orbits, or most of the pair members in the present sample are experiencing unbound encounters.

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