- ID:
- ivo://CDS.VizieR/J/ApJ/870/122
- Title:
- Spectroscopy of low-metallicity star candidates
- Short Name:
- J/ApJ/870/122
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results from an observing campaign to identify low-metallicity stars in the Best & Brightest Survey. From medium-resolution (R~1200-2000) spectroscopy of 857 candidates, we estimate the stellar atmospheric parameters (T_eff_, logg, and [Fe/H]), as well as carbon and {alpha}-element abundances. We find that 69% of the observed stars have [Fe/H]<=-1.0, 39% have [Fe/H]<=-2.0, and 2% have [Fe/H]<=-3.0. There are also 133 carbon-enhanced metal-poor (CEMP) stars in this sample, with 97 CEMP Group I and 36 CEMP Group II stars identified in the A(C) versus [Fe/H] diagram. A subset of the confirmed low-metallicity stars were followed-up with high-resolution spectroscopy, as part of the R-process Alliance, with the goal of identifying new highly and moderately r-process-enhanced stars. Comparison between the stellar atmospheric parameters estimated in this work and from high-resolution spectroscopy exhibit good agreement, confirming our expectation that medium-resolution observing campaigns are an effective way of selecting interesting stars for further, more targeted, efforts.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/748/29
- Title:
- Spectroscopy of M87 globular clusters
- Short Name:
- J/ApJ/748/29
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The halos of galaxies preserve unique records of their formation histories. We carry out the first combined observational and theoretical study of phase-space halo substructure in an early-type galaxy: M87, the central galaxy in the Virgo cluster. We analyze an unprecedented wide-field, high-precision photometric and spectroscopic data set for 488 globular clusters (GCs), which includes new, large-radius Subaru/Suprime-Cam and Keck/DEIMOS observations. We find signatures of two substructures in position-velocity phase space. One is a small, cold stream associated with a known stellar filament in the outer halo; the other is a large shell-like pattern in the inner halo that implies a massive, hitherto unrecognized accretion event. We perform extensive statistical tests and independent metallicity analyses to verify the presence and characterize the properties of these features, and to provide more general methodologies for future extragalactic studies of phase-space substructure. The cold outer stream is consistent with a dwarf galaxy accretion event, while for the inner shell there is tension between a low progenitor mass implied by the cold velocity dispersion, and a high mass from the large number of GCs, which might be resolved by a ~0.5 L* E/S0 progenitor.
- ID:
- ivo://CDS.VizieR/J/ApJ/769/10
- Title:
- Spectroscopy of M31 globular clusters
- Short Name:
- J/ApJ/769/10
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the results of an [OIII]{lambda}5007 spectroscopic survey for planetary nebulae (PNe) located within the star clusters of M31. By examining R~5000 spectra taken with the WIYN+Hydra spectrograph, we identify 3 PN candidates in a sample of 274 likely globular clusters, 2 candidates in objects which may be globular clusters, and 5 candidates in a set of 85 younger systems. The possible PNe are all faint, between ~2.5 and ~6.8mag down the PN luminosity function, and, partly as a consequence of our selection criteria, have high excitation, with [OIII]{lambda}5007 to H{beta} ratios ranging from 2 to >~12. We discuss the individual candidates, their likelihood of cluster membership, and the possibility that they were formed via binary interactions within the clusters. Our data are consistent with the suggestion that PN formation within globular clusters correlates with binary encounter frequency, though, due to the small numbers and large uncertainties in the candidate list, this study does not provide sufficient evidence to confirm the hypothesis.
- ID:
- ivo://CDS.VizieR/J/AJ/143/126
- Title:
- Spectroscopy of 462 nearby Type Ia supernovae
- Short Name:
- J/AJ/143/126
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present 2603 spectra of 462 nearby Type Ia supernovae (SNe Ia), including 2065 previously unpublished spectra, obtained during 1993-2008 through the Center for Astrophysics Supernova Program. There are on average eight spectra for each of the 313 SNe Ia with at least two spectra. Most of the spectra were obtained with the FAST spectrograph at the Fred Lawrence Whipple Observatory 1.5m telescope and reduced in a consistent manner, making this data set well suited for studies of SN Ia spectroscopic diversity. Using additional data from the literature, we study the spectroscopic and photometric properties of SNe Ia as a function of spectroscopic class using the classification schemes of Branch et al. (2006PASP..118..560B) and Wang et al. (2009, Cat. J/ApJ/699/L139). The width-luminosity relation appears to be steeper for SNe Ia with broader lines, although the result is not statistically significant with the present sample. Based on the evolution of the characteristic SiII{lambda}6355 line, we propose improved methods for measuring velocity gradients, revealing a larger range than previously suspected, from ~0 to ~400km/s/day considering the instantaneous velocity decline rate at maximum light.
- ID:
- ivo://CDS.VizieR/J/AJ/123/2828
- Title:
- Spectroscopy of northern NLTT stars
- Short Name:
- J/AJ/123/2828
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present initial results of an all-sky search for late-type dwarfs within 20pc of the Sun using the New Luyten Two-Tenths (NLTT) catalog cross-referenced with the Two Micron All Sky Survey (2MASS) database. The results were obtained with low-resolution optical spectroscopic follow-up of candidate nearby stars as a preliminary test of our methodology. M_J_, derived using spectral indices, and 2MASS J are used to estimate distances. Out of the 70 objects observed, 28 are identified as previously unrecognized objects within 25pc of the Sun, and up to 19 of these are within 20pc. One, LP 647-13, is an M9-type dwarf at 10.5pc, making it one of the four closest M9 dwarfs currently known. We also discuss the chromospheric activity of the observed dwarfs.
- ID:
- ivo://CDS.VizieR/J/A+A/574/A109
- Title:
- Spectroscopy of Planetary Nebulae in NGC 5128
- Short Name:
- J/A+A/574/A109
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Planetary nebulae (PNe) are excellent tracers of the common low mass stars through their strong and narrow emission lines. The velocities of large numbers of PNe are excellent tracers of galaxy kinematics. NGC 5128, the nearest large early-type galaxy offers the possibility to gather a large PN sample. Imaging and spectroscopic observations of PNe in NGC 5128 were obtained to find PNe and measure their velocities. Combined with literature data, a large sample of high quality kinematic probes is assembled for dynamical studies in NGC 5128. NTT Imaging was obtained in 15 fields in NGC 5128 over 1 degree with EMMI and [OIII] and off-band filters. Newly detected emission sources, combined with literature PN, were used as input for FLAMES multi-fibre spectroscopy in MEDUSA mode. Spectra of the 4600-5100{AA} region were analysed and velocities were measured based on [OIII]4959,5007{AA} and often H{beta}. The chief results are catalogues of 1118 PN candidates and 1267 spectroscopically confirmed PNe in NGC 5128. The catalogue of PN candidates contains 1060 potential PNe discovered with NTT EMMI imaging and 58 from literature surveys. The spectroscopically confirmed PN catalogue has FLAMES radial velocity and emission line measurements for 1135 PNe, of which 486 are newly confirmed here. An additional 132 PN radial velocities are available from the literature. For 629 PNe observed with FLAMES, H-beta was measured in addition to the [OIII] emission lines. Nine targets show double-lined or more complex profiles (19 components in total), and their possible origin is discussed. FLAMES spectra of 48 globular clusters were also targetted, and 11 had emission lines detected (two with multiple components), but only 3 are PNe likely to belong to the host globular. Conclusions. The total of 1267 confirmed PNe in NGC 5128 with radial velocity measurements, of which 1135 have small velocity errors, is the largest such collection of individual kinematic probes in an early-type galaxy. This PN dataset, as well as the catalogue of 1118 PN candidates, are valuable resources for detailed investigation of the kinematics and stellar population of NGC 5128.
- ID:
- ivo://CDS.VizieR/J/ApJ/902/17
- Title:
- Spectroscopy of quiescent gal. in 9 lensing clusters
- Short Name:
- J/ApJ/902/17
- Date:
- 03 Mar 2022 11:35:20
- Publisher:
- CDS
- Description:
- We measure the central stellar velocity dispersion function for quiescent galaxies in a set of nine northern clusters in the redshift range 0.18<z<0.29 and with strong lensing arcs in Hubble Space Telescope images. The velocity dispersion function links galaxies directly to their dark matter halos. From dense SDSS and MMT/Hectospec spectroscopy, we identify 222-463 spectroscopic members in each cluster. We derive physical properties of cluster members including redshift, D_n_4000, and central stellar velocity dispersion and we include a table of these measurements for 3419 cluster members. We construct the velocity dispersion functions for quiescent galaxies with D_n_4000>1.5 and within R200. The cluster velocity dispersion functions all show excesses at {sigma}>~250km/s compared to the field velocity dispersion function. The velocity dispersion function slope at large velocity dispersion ({sigma}>160km/s) is steeper for more massive clusters, consistent with the trend observed for cluster luminosity functions. The spatial distribution of galaxies with large velocity dispersion at radii larger than R200 further underscores the probable major role of dry mergers in the growth of massive cluster galaxies during cluster assembly.
6188. Spectroscopy of Segue 1
- ID:
- ivo://CDS.VizieR/J/ApJ/692/1464
- Title:
- Spectroscopy of Segue 1
- Short Name:
- J/ApJ/692/1464
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present Keck/DEIMOS spectroscopy of Segue 1, an ultra-low-luminosity (M_V_=-1.5^+0.6^_-0.8_) Milky Way satellite companion. While the combined size and luminosity of Segue 1 are consistent with either a globular cluster or a dwarf galaxy, we present spectroscopic evidence that this object is a dark matter-dominated dwarf galaxy. We identify 24 stars as members of Segue 1 with a mean heliocentric recession velocity of 206+/-1.3km/s. Although Segue 1 spatially overlaps the leading arm of the Sagittarius stream, its velocity is 100km/s different from that predicted for recent Sagittarius tidal debris at this position. Using spectral synthesis modeling, we derive a metallicity for the single red giant branch star in our sample of [Fe/H]=-3.3+/-0.2dex. We conclude that Segue 1 is the least luminous of the ultra-faint galaxies recently discovered around the Milky Way, and is thus the least-luminous known galaxy.
- ID:
- ivo://CDS.VizieR/J/ApJ/691/1387
- Title:
- Spectroscopy of the Galactic bar. I.
- Short Name:
- J/ApJ/691/1387
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We use Fabry-Perot absorption line imaging spectroscopy to measure radial velocities using the CaII line in 3360 stars toward three lines of sight in the Milky Way's bar: Baade's Window and offset position at (l,b)~(+/-5.0,-3.5{deg}). This sample includes 2488 bar red clump giants, 339 bar M/K-giants, and 318 disk main-sequence stars. We measure the first four moments of the stellar velocity distribution of the red clump giants, and find it to be symmetric and flat-topped. We also measure the line-of-sight average velocity and dispersion of the red clump giants as a function of distance in the bar.
- ID:
- ivo://CDS.VizieR/J/A+A/477/717
- Title:
- Spectroscopy of Type Ia supernovae
- Short Name:
- J/A+A/477/717
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a quantitative study of a new data set of high redshift Type Ia supernovae spectra, observed at the Gemini telescopes during the first 34 months of the Supernova Legacy Survey. During this time 123 supernovae candidates were observed, of which 87 have been identified as SNe Ia at a median redshift of z=0.720. Spectra from the entire second year of the survey and part of the third year (59 total SNe candidates with 46 confirmed SNe Ia) are published here for the first time. The spectroscopic measurements made on this data set are used determine if these distant SNe comprise a population similar to those observed locally. Rest-frame equivalent width and ejection velocity measurements are made on four spectroscopic features. Corresponding measurements are presented for a set of 167 spectra from 24 low-z SNe Ia from the literature.
