- ID:
- ivo://CDS.VizieR/J/A+A/633/A120
- Title:
- SgrB2(M) ^13^CCC and C^13^CC spectra
- Short Name:
- J/A+A/633/A120
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Carbon molecules and their ^13^C-isotopologues can be used to determine the ^12^C/^13^C abundance ratios in stellar and interstellar objects. C3 is a pure carbon chain molecule found in star forming regions and in stellar shells of carbon-rich late-type stars. Latest laboratory data of ^13^C-isotopologues of C3 allow a selective search for the mono-substituted species ^13^CCC and C^13^CC based on accurate ro-vibrational frequencies. Our aim was to provide the first detection of the ^13^C-isotopologues ^13CCC and C^13^CC in space and to derive the ^12^C/ ^13^C ratio of interstellar gas in the massive star-forming region SgrB2(M) near the Galactic Center. We used the heterodyne receivers GREAT and upGREAT on board SOFIA to search for the ro-vibrational transitions Q(2) and Q(4) of ^13^CCC and C^13^CC at 1.9THz along the line of sight towards SgrB2(M). In addition, to determine the local excitation temperature we analyzed data from nine ro-vibrational transitions of the main isotopologue CCC in the frequency range between 1.6-1.9THz which were taken from the Herschel Science Data Archive. We report the first detection of the isotopologues ^13^CCC and C^13^CC. For both species the ro-vibrational absorption lines Q(2) and Q(4) have been identified, primarily arising from the warm gas physically associated with the strong continuum source SgrB2(M). From the available CCC ro-vibrational transitions we derived a gas excitation temperature of Tex=44.4^+4.7^_-3.9_K and a total column density of N(CCC)=3.88^+0.39^_-0.35_x10^15^cm^-2.. Assuming the excitation temperatures of C^13^CC and ^13^CCC to be the same as for CCC, we obtained column densities of the ^13^C-isotopologues of N(C^13^CC)=2.1^+0.9^_-0.6^_x10^14^cm^-2^ and N(^13^CCC)=2.4^+1.2^_-0.8_x10^14^cm^-2^. The derived ^12^C/^13^C abundance ratio in the C3 molecules is 20.5+/-4.2, which is in agreement with the elemental ratio of 20, typically observed in SgrB2(M). However, we find the N(^13^CCC)/N(C^13^CC) ratio to be 1.2+/-0.1, which is shifted from the statistically expected value of 2. We propose that the discrepant abundance ratio arises due to the the lower zero-point energy of C^13^CC which makes position- exchange reaction converting C^13^CC to C^13^CC energetically favorable.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/605/A46
- Title:
- Sgr dSph nucleus stars chemical abundances
- Short Name:
- J/A+A/605/A46
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present Iron, Magnesium, Calcium, and Titanium abundances for 235 stars in the central region of the Sagittarius dwarf spheroidal galaxy (within 9.0'~=70pc from the center) from medium-resolution Keck/DEIMOS spectra. All the considered stars belong to the massive globular cluster M 54 or to the central nucleus of the galaxy (Sgr,N). In particular we provide abundances for 109 stars with [Fe/H]>=-1.0, more than doubling the available sample of spectroscopic metallicity and {alpha}-elements abundance estimates for Sgr dSph stars in this metallicity regime. We find for the first time a metallicity gradient in the Sgr,N population, whose peak iron abundance goes from [Fe/H]=-0.38 for R<=2.5' to [Fe/H]=-0.57 for 5.0<R<=9.0 arcmin. On the other hand the trends of [Mg/Fe], [Ca/Fe], and [Ti/Fe] with [Fe/H] are the same over the entire region explored by our study. We reproduce the observed chemical patterns of the Sagittarius dwarf spheroidal as a whole with a chemical evolution model implying a high mass progenitor (M_DM_=6x10^10^M_{sun}_) and a significant event of mass-stripping occurred a few Gyr ago, presumably starting at the first peri-Galactic passage after infall.
- ID:
- ivo://CDS.VizieR/J/MNRAS/427/2647
- Title:
- Sgr dSph stars spectral classification
- Short Name:
- J/MNRAS/427/2647
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present spectra of 1142 colour-selected stars in the direction of the Sagittarius Dwarf Spheroidal (Sgr dSph) galaxy, of which 1058 were taken with VLT/FLAMES multi-object spectrograph and 84 were taken with the SAAO Radcliffe 1.9-m telescope grating spectrograph. Spectroscopic membership is confirmed (at >99 per cent confidence) for 592 stars on the basis of their radial velocity, and spectral types are given. Very slow rotation is marginally detected around the galaxy's major axis. We identify five S stars and 23 carbon stars, of which all but four carbon stars are newly determined and all but one (PQ Sgr) are likely Sgr dSph members. We examine the onset of carbon richness in this metal-poor galaxy in the context of stellar models. We compare the stellar death rate (one star per 1000-1700yr) with the known planetary nebula dynamical ages and find that the bulk population produce the observed (carbon-rich) planetary nebulae. We compute average lifetimes of S and carbon stars as 60-250 and 130-500kyr, compared to a total thermal-pulsing asymptotic giant branch lifetime of 530-1330kyr. We conclude by discussing the return of carbon-rich material to the interstellar medium.
- ID:
- ivo://CDS.VizieR/J/ApJS/213/35
- Title:
- SHELS: complete galaxy redshift survey for R<=20.6
- Short Name:
- J/ApJS/213/35
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The SHELS (Smithsonian Hectospec Lensing Survey) is a complete redshift survey covering two well-separated fields (F1 and F2) of the Deep Lens Survey to a limiting R=20.6. Here we describe the redshift survey of the F2 field (RA_J2000_=09h19m32.4s and DE_J2000_=+30{deg}00'00"). The survey includes 16294 new redshifts measured with the Hectospec on the MMT. The resulting survey of the 4deg^2^ F2 field is 95% complete to R=20.6, currently the densest survey to this magnitude limit. The median survey redshift is z=0.3; the survey provides a view of structure in the range 0.1<~z<~0.6. An animation displays the large-scale structure in the survey region. We provide a redshift, spectral index D_n_4000, and stellar mass for each galaxy in the survey. We also provide a metallicity for each galaxy in the range 0.2<z<0.38. To demonstrate potential applications of the survey, we examine the behavior of the index D_n_4000 as a function of galaxy luminosity, stellar mass, and redshift. The known evolutionary and stellar mass dependent properties of the galaxy population are cleanly evident in the data. We also show that the mass-metallicity relation previously determined from these data is robust to the analysis approach.
- ID:
- ivo://CDS.VizieR/J/AJ/143/102
- Title:
- SHELS galaxies with 0.02<z<0.1
- Short Name:
- J/AJ/143/102
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Smithsonian Hectospec Lensing Survey (SHELS) is a dense redshift survey covering a 4deg^2^ region to a limiting R=20.6. In the construction of the galaxy catalog and in the acquisition of spectroscopic targets, we paid careful attention to the survey completeness for lower surface brightness dwarf galaxies. Thus, although the survey covers a small area, it is a robust basis for computation of the slope of the faint end of the galaxy luminosity function to a limiting M_R_=-13.3+5logh. We calculate the faint-end slope in the R band for the subset of SHELS galaxies with redshifts in the range 0.02<=z<0.1, SHELS_0.1_. This sample contains 532 galaxies with R<20.6 and with a median surface brightness within the half-light radius of SB_50,R_=21.82mag/arcsec^2^. We used this sample to make one of the few direct measurements of the dependence of the faint end of the galaxy luminosity function on surface brightness. For the sample as a whole the faint-end slope, {alpha}=-1.31+/-0.04, is consistent with both the Blanton et al. analysis of the Sloan Digital Sky Survey (2005ApJ...631..208B, 2005AJ....129.2562B) and the Liu et al. analysis of the COSMOS field (2008ApJ...672..198L). This consistency is impressive given the very different approaches of these three surveys. A magnitude-limited sample of 135 galaxies with optical spectroscopic redshifts with mean half-light surface brightness, SB_50,R_>=22.5mag/arcsec^2^ is unique to SHELS_0.1_. The faint-end slope is {alpha}_22.5_=-1.52+/-0.16. SHELS_0.1_ shows that lower surface brightness objects dominate the faint-end slope of the luminosity function in the field, underscoring the importance of surface brightness limits in evaluating measurements of the faint-end slope and its evolution.
- ID:
- ivo://CDS.VizieR/J/ApJ/872/91
- Title:
- SHELS galaxy sizes using Subaru/HSC imaging
- Short Name:
- J/ApJ/872/91
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We explore the relationships between size, stellar mass, and average stellar population age (indicated by D_n_4000 indices) for a sample of ~11000 intermediate-redshift galaxies from the SHELS spectroscopic survey (Geller+ 2014, J/ApJS/213/35) augmented by high-resolution Subaru Telescope Hyper Suprime-Cam imaging. In the redshift interval 0.1<z<0.6, star-forming galaxies are on average larger than their quiescent counterparts. The mass-complete sample of ~3500M_*_>10^10^M_{sun}_ quiescent galaxies shows that the average size of a 10^11^M_{sun}_ quiescent galaxy increases by <~25% from z~0.6 to z~0.1. This growth rate is a function of stellar mass: the most massive (M_*_>10^10^M_{sun}_) galaxies grow significantly more slowly in size than quiescent systems an order of magnitude less massive that grow by 70% in the 0.1<~z<~0.3 redshift interval. For M_*_<10^11^M_{sun}_ galaxies, age and size are anticorrelated at fixed mass; more massive quiescent systems show no significant trend in size with average stellar population age. The evolution in absolute and fractional abundances of quiescent systems at intermediate redshift are also a function of galaxy stellar mass. The suite of evolutionary trends suggests that galaxies more massive than ~10^11^M_{sun}_ have mostly assembled their mass by z~0.6. Quiescent galaxies with lower stellar masses show more complex evolution that is characterized by a combination of individual quiescent galaxy size growth (through mergers) and an increase in the size of newly quenched galaxies joining the population at later times (progenitor bias). The low-mass population (M_*_~10^10^M_{sun}_) grows predominantly as a result of progenitor bias. For more massive (M_*_~5x10^10^M_{sun}_) quiescent galaxies, (predominantly minor) mergers and progenitor bias make more comparable contributions to the size growth. At intermediate redshift, quiescent size growth is mass-dependent; the most massive (M_*_>10^10^M_{sun}_) galaxies experience the least rapid increase in size from z~0.6 to z~0.1.
- ID:
- ivo://CDS.VizieR/J/ApJS/224/11
- Title:
- SHELS: redshift survey of the F1 DLS field
- Short Name:
- J/ApJS/224/11
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Smithsonian Hectospec Lensing Survey (SHELS) is a complete redshift survey covering two well-separated fields (F1 and F2) of the Deep Lens Survey (DLS). Both fields are more than 94% complete to a Galactic extinction corrected R_0_=20.2. Here, we describe the redshift survey of the F1 field centered at RA=00:53:25.3 and DEC=12:33:55 (J2000); like F2, the F1 field covers ~4deg^2^. The redshift survey of the F1 field includes 9426 new galaxy redshifts measured with Hectospec on the MMT (published here). As a guide to future uses of the combined survey, we compare the mass metallicity relation and the distributions of D_n_4000 as a function of stellar mass and redshift for the two fields. The mass-metallicity relations differ by an insignificant 1.6{sigma}. For galaxies in the stellar mass range 10^10^-10^11^M_{sun}_, the increase in the star-forming fraction with redshift is remarkably similar in the two fields. The seemingly surprising 31%-38% difference in the overall galaxy counts in F1 and F2 is probably consistent with the expected cosmic variance given the subtleties of the relative systematics in the two surveys. We also review the DLS cluster detections in the two fields: poorer photometric data for F1 precluded secure detection of the single massive cluster at z=0.35 that we find in SHELS. Taken together, the two fields include 16055 redshifts for galaxies with R_0_<=20.2 and 20754 redshifts for galaxies with R<=20.6. These dense surveys in two well-separated fields provide a basis for future investigations of galaxy properties and large-scale structure.
- ID:
- ivo://CDS.VizieR/J/ApJ/861/94
- Title:
- SHINING I. Survey observational trends
- Short Name:
- J/ApJ/861/94
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We use the Herschel/PACS spectrometer to study the global and spatially resolved far-infrared (FIR) fine-structure line emission in a sample of 52 galaxies that constitute the SHINING survey. These galaxies include star-forming, active-galactic nuclei (AGNs), and luminous infrared galaxies (LIRGs). We find an increasing number of galaxies (and kiloparsec-size regions within galaxies) with low line-to-FIR continuum ratios as a function of increasing FIR luminosity (LFIR), dust infrared color, LFIR to molecular gas mass ratio (LFIR/Mmol), and FIR surface brightness ({Sigma}FIR). The correlations between the [CII]/FIR or [OI]/FIR ratios with {Sigma}FIR are remarkably tight (~0.3dex scatter over almost four orders of magnitude in {Sigma}FIR). We observe that galaxies with L_FIR_/M_mol_>~80L_{sun}_/M_{sun}_ and {Sigma}FIR>~10^11^L_{sun}_/kpc^2^ tend to have weak fine-structure line-to-FIR continuum ratios, and that LIRGs with infrared sizes >~1kpc have line-to-FIR ratios comparable to those observed in typical star-forming galaxies. We analyze the physical mechanisms driving these trends in Paper II. The combined analysis of the [CII], [NII]122{mu}m, and [OIII]88{mu}m lines reveals that the fraction of the [CII] line emission that arises from neutral gas increases from 60% to 90% in the most active star-forming regions and that the emission originating in the ionized gas is associated with low-ionization, diffuse gas rather than with dense gas in HII regions. Finally, we report the global and spatially resolved line fluxes of the SHINING galaxies to enable the comparison and planning of future local and high-z studies.
- ID:
- ivo://CDS.VizieR/J/ApJS/249/31
- Title:
- Short period spec. & EBs (LPSEB) from LAMOST & PTF
- Short Name:
- J/ApJS/249/31
- Date:
- 10 Dec 2021 16:35:10
- Publisher:
- CDS
- Description:
- Binaries play key roles in determining stellar parameters and exploring stellar evolution models. We build a catalog of 88 eclipsing binaries with spectroscopic information, taking advantage of observations from both the Large Sky Area Multi-Object fiber Spectroscopic Telescope (LAMOST) and the Palomar Transient Factory (PTF) surveys. A software pipeline is constructed to identify binary candidates by examining their light curves. The orbital periods of binaries are derived from the Lomb-Scargle method. The key distinguishing features of eclipsing binaries are recognized by a new filter, Flat Test. We classify the eclipsing binaries by applying a Fourier analysis on the light curves. Among all the binary stars, 13 binaries are identified as eclipsing binaries for the first time. The catalog contains the following information: the position, primary eclipsing magnitude and time, eclipsing depth, the number of photometry and radial velocity observations, largest radial velocity difference, binary type, the effective temperature of the observable star Teff, and surface gravity of the observable star logg. The false-positive probability is calculated by using both a Monte Carlo simulation and real data from the Sloan Digital Sky Survey Stripe 82 Standard Catalog. The binaries in the catalog are mostly with a period of less than one day. The period distribution shows a 0.22 day cutoff, which is consistent with the low probability of an eclipsing binary rotating with such a period.
- ID:
- ivo://CDS.VizieR/J/ApJS/220/20
- Title:
- Si and Ca high-velocity features in SNe Ia
- Short Name:
- J/ApJS/220/20
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The high-velocity features (HVFs) in optical spectra of type Ia supernovae (SNe Ia) are examined with a large sample including very early-time spectra (e.g., t<-7days). Multiple Gaussian fits are applied to examine the HVFs and their evolutions, using constraints on expansion velocities for the same species (i.e., SiII5972 and SiII6355). We find that strong HVFs tend to appear in SNe Ia with smaller decline rates (e.g., {Delta}m_15_(B)<~1.4mag), clarifying that the finding by Childress et al. (2014MNRAS.437..338C) for the Ca-HVFs in near-maximum-light spectra applies both to the Si-HVFs and Ca-HVFs in the earlier phase. The Si-HVFs seem to be more common in rapidly expanding SNe Ia, which is different from the earlier result that Ca-HVFs are associated with SNe Ia that have slower SiII6355 velocities at maximum light (i.e., V^Si^_max_). Moreover, SNe Ia with both stronger HVFs at early phases and larger V^Si^_max_ are found to have noticeably redder B-V colors and to occur preferentially in the inner regions of their host galaxies, while those with stronger HVFs but smaller V^Si^_max_ show opposite tendencies, suggesting that these two subclasses have different explosion environments and their HVFs may have different origins. We further examine the relationships between the absorption features of SiII6355 and CaII IR lines, and find that their photospheric components are well correlated in velocity and strength but that the corresponding HVFs show larger scatter. These results cannot be explained with ionization and/or thermal processes alone, and different mechanisms are required for the creation of HVF-forming regions in SNe Ia.
