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521. Southern Stars embedded in nebulosity
ID:
ivo://CDS.VizieR/VII/218
Title:
Southern Stars embedded in nebulosity
Short Name:
VII/218
Date:
21 Oct 2021
Publisher:
CDS
Description:
A survey of the Milky Way southward of the Palomar Sky Survey for the identification of reflection nebulae was carried out at the Cerro Tololo Inter-American Observatory in Chile. Plates in blue light were obtained at the Curtis Schmidt telescope covering a strip of plus or minus six degrees of the galactic equator. Red sensitive plates for comparison were also obtained with the same telescope covering the same area near the galactic plane. Observatory staff members and some students of the University of Toronto, Canada assisted in identifying stars embedded in nebulosity as shown by the plates. Although this catalogue roughly complements the Catalogue of Reflection Nebulae of van den Berg (1966AJ.....71..990V, Cat. <VII/21>), the region here surveyed is more narrowly confined to the galactic equator.
522. Spaghetti Survey
ID:
ivo://CDS.VizieR/J/AJ/120/2496
Title:
Spaghetti Survey
Short Name:
J/AJ/120/2496
Date:
21 Oct 2021
Publisher:
CDS
Description:
The Spaghetti project is a pencil-beam photometric and spectroscopic survey designed to identify structure in the Galactic halo. Four-color stellar photometry in the modified Washington filter set is used to identify halo stars for spectroscopic observations. The filters include C, M, T2 and DDO51. The fields in the survey are chosen from high Galactic-latitude positions with low reddening and no stars as bright as SAO stars. Thus far we have imaged 134 fields covering a total area of 52deg^2^. These fields are listed in table1.dat. Due to weather, the only fully calibrated photometry was measured from images taken with the BTC ccd mosaic camera on the CTIO 4m telescope in April 1999. Table4.dat lists these stars from the 53 BTC fields, which covers a total area of 13 square degrees. These data include only those stars whose measurement errors are less than 0.04 in all four filters (32655 total stars). Photometric measurements of stars in the other fields will be published as soon as they can be fully calibrated. See <GCPD/48> for a short description of the Washington Photometric system.
523. Spectral classification of O Vz stars from GOSSS
ID:
ivo://CDS.VizieR/J/AJ/152/31
Title:
Spectral classification of O Vz stars from GOSSS
Short Name:
J/AJ/152/31
Date:
21 Oct 2021
Publisher:
CDS
Description:
On the basis of the Galactic O Star Spectroscopic Survey (GOSSS), we present a detailed systematic investigation of the O Vz stars. The currently used spectral classification criteria are rediscussed, and the Vz phenomenon is recalibrated through the addition of a quantitative criterion based on the equivalent widths of the HeI{lambda}4471, HeII{lambda}4542, and HeII{lambda}4686 spectral lines. The GOSSS O Vz and O V populations resulting from the newly adopted spectral classification criteria are comparatively analyzed. The locations of the O Vz stars are probed, showing a concentration of the most extreme cases toward the youngest star-forming regions. The occurrence of the Vz spectral peculiarity in a solar-metallicity environment, as predicted by the FASTWIND code, is also investigated, confirming the importance of taking into account several processes for the correct interpretation of the phenomenon.
524. Spectral line survey of two LOSs
ID:
ivo://CDS.VizieR/J/MNRAS/446/3842
Title:
Spectral line survey of two LOSs
Short Name:
J/MNRAS/446/3842
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the results of two Mopra 3-mm spectral line surveys of the lines of sight (LOS) towards the Galactic Centre (GC) molecular complexes Sgr B2 (LOS+0.693) and Sgr A (LOS-0.11). The spectra covered the frequency ranges of ~77-93 GHz and ~105-113 GHz. We have detected 38 molecular species and 25 isotopologues. The isotopic ratios derived from column density ratios are consistent with the canonical values, indicating that chemical isotopic fractionation and/or selective photodissociation can be considered negligible (<10 percent) for the GC physical conditions. The derived abundances and rotational temperatures are very similar for both LOSs, indicating very similar chemical and excitation conditions for the molecular gas in the GC. The excitation conditions are also very similar to those found for the nucleus of the starburst galaxy NGC 253. We report for the first time the detection of HCO and HOC^+^ emission in LOS+0.693. Our comparison of the abundance ratios between CS, HCO, HOC^+^ and HCO^+^ found in the two LOSs with those in typical Galactic photodissociation regions (PDRs) and starbursts galaxies does not show any clear trend to distinguish between ultraviolet- and X-ray-induced chemistries. We propose that the CS/HOC^+^ ratio could be used as a tracer of the PDR components in the molecular clouds in the nuclei of galaxies.
525. Spectral Survey of Southern Milky Way
ID:
ivo://CDS.VizieR/III/40A
Title:
Spectral Survey of Southern Milky Way
Short Name:
III/40A
Date:
21 Oct 2021
Publisher:
CDS
Description:
The spectral survey, carried out at the Stockholm Observatory, was initiated by B. Lindblad. The observational material was obtained by L.O. Loden, K. Loden and others in the years 1956-1965, when the Stockholm Observatory took part in a joint enterprise for using the Harvard-Boyden station. The Swedish Natural Science Research Council, the Royal Academy of the Sciences, and the K. and A. Wallenberg Foundation funded the observations, which are based on both direct and objective prism plates. The data were published in three parts, the first having less precise positions than the others. The coordinates for Catalogue I (3033) were later recomputed with the same reduction procedure as Catalogues II (3034) and III (3035), making the present catalogue uniform (Andersen, 1977). The files include star identification, finding chart identification, RA and Dec, galactic longitude and latitude, spectral type, blue magnitude, visual magnitude and remarks. The data concerning the part 2 were revised by Brian Skiff in November 1996 (see the "History" section below)
526. Spectrophotometric parallaxes with linear models
ID:
ivo://CDS.VizieR/J/AJ/158/147
Title:
Spectrophotometric parallaxes with linear models
Short Name:
J/AJ/158/147
Date:
07 Jan 2022 11:19:14
Publisher:
CDS
Description:
With contemporary infrared spectroscopic surveys like APO Galactic Evolution Experiment (APOGEE), red-giant stars can be observed to distances and extinctions at which Gaia parallaxes are not highly informative. Yet the combination of effective temperature, surface gravity, composition, and age-all accessible through spectroscopy - determines a giant's luminosity. Therefore spectroscopy plus photometry should enable precise spectrophotometric distance estimates. Here we use the overlap of APOGEE, Gaia, the Two Micron All Sky Survey (2MASS), and the Wide-field Infrared Survey Explorer (WISE) to train a data-driven model to predict parallaxes for red-giant branch stars with 0<logg=<2.2 (more luminous than the red clump). We employ (the exponentiation of) a linear function of APOGEE spectral pixel intensities and multiband photometry to predict parallax spectrophotometrically. The model training involves no logarithms or inverses of the Gaia parallaxes, and needs no cut on the Gaia parallax signal-to-noise ratio. It includes an L1 regularization to zero out the contributions of uninformative pixels. The training is performed with leave-out subsamples such that no star's astrometry is used even indirectly in its spectrophotometric parallax estimate. The model implicitly performs a reddening and extinction correction in its parallax prediction, without any explicit dust model. We assign to each star in the sample a new spectrophotometric parallax estimate; these parallaxes have uncertainties of less than 15%, depending on data quality, which is more precise than the Gaia parallax for the vast majority of targets, and certainly any stars more than a few kiloparsec distance. We obtain 10% distance estimates out to heliocentric distances of 20 kpc, and make global maps of the Milky Way's disk.
527. Spectroscopic and photometric properties of Tombaugh 1
ID:
ivo://CDS.VizieR/J/AJ/151/6
Title:
Spectroscopic and photometric properties of Tombaugh 1
Short Name:
J/AJ/151/6
Date:
21 Oct 2021
Publisher:
CDS
Description:
Open clusters can be the key to deepening our knowledge on various issues involving the structure and evolution of the Galactic disk and details of stellar evolution because a cluster's properties are applicable to all its members. However, the number of open clusters with detailed analysis from high-resolution spectroscopy or precision photometry imposes severe limitations on studies of these objects. To expand the number of open clusters with well-defined chemical abundances and fundamental parameters, we investigate the poorly studied, anticenter open cluster Tombaugh 1. Using precision uvbyCaH{beta} photometry and high-resolution spectroscopy, we derive the cluster's reddening, obtain photometric metallicity estimates, and, for the first time, present a detailed abundance analysis of 10 potential cluster stars (nine clump stars and one Cepheid). Using the radial position from the cluster center and multiple color indices, we have isolated a sample of unevolved, probable single-star members of Tombaugh 1. From 51 stars, the cluster reddening is found to be E(b-y)=0.221+/-0.006 or E(B-V)=0.303+/-0.008, where the errors refer to the internal standard errors of the mean. The weighted photometric metallicity from m_1_ and hk is [Fe/H]=-0.10+/-0.02, while a match to the Victoria-Regina Stromgren isochrones leads to an age of 0.95+/-0.10 Gyr and an apparent modulus of (m-M)=13.10+/-0.10. Radial velocities identify six giants as probable cluster members, and the elemental abundances of Fe, Na, Mg, Al, Si, Ca, Ti, Cr, Ni, Y, Ba, Ce, and Nd have been derived for both the cluster and the field stars. Tombaugh 1 appears to be a typical inner thin disk, intermediate-age open cluster of slightly subsolar metallicity, located just beyond the solar circle, with solar elemental abundance ratios except for the heavy s-process elements, which are a factor of two above solar. Its metallicity is consistent with a steep metallicity gradient in the galactocentric region between 9.5 and 12 kpc. Our study also shows that Cepheid XZ CMa is not a member of Tombaugh 1 and reveals that this Cepheid presents signs of barium enrichment, making it a probable binary star.
528. Spectroscopy of globular clusters
ID:
ivo://CDS.VizieR/J/A+A/601/A96
Title:
Spectroscopy of globular clusters
Short Name:
J/A+A/601/A96
Date:
21 Oct 2021
Publisher:
CDS
Description:
We test the performance of our analysis technique for integrated-light spectra by applying it to seven well-studied Galactic GCs that span a wide range of metallicities. Integrated-light spectra were obtained by scanning the slit of the UVES spectrograph on the ESO Very Large Telescope across the half-light diameters of the clusters. We modelled the spectra using resolved Hubble Space Telescope colour-magnitude diagrams (CMDs), as well as theoretical isochrones, in combination with standard stellar atmosphere and spectral synthesis codes. The abundances of Fe, Na, Mg, Ca, Ti, Cr, and Ba were compared with literature data for individual stars in the clusters. The typical differences between iron abundances derived from our integrated-light spectra and those compiled from the literature are less than 0.1 dex. A larger difference is found for one cluster (NGC 6752), and is most likely caused primarily by stochastic fluctuations in the numbers of bright red giants within the scanned area. As expected, the alpha-elements (Ca, Ti) are enhanced by about 0.3 dex compared to the Solar-scaled composition, while the [Cr/Fe] ratios are close to Solar. When using up-to-date line lists, our [Mg/Fe] ratios also agree well with literature data. Our [Na/Fe] ratios are, on average, 0.08-0.14 dex lower than average values quoted in the literature, and our [Ba/Fe] ratios may be overestimated by 0.20-0.35 dex at the lowest metallicities. We find that analyses based on theoretical isochrones give very similar results to those based on resolved CMDs. Overall, the agreement between our integrated-light abundance measurements and the literature data is satisfactory. Refinements of the modelling procedure, such as corrections for stellar evolutionary and non-LTE effects, might further reduce some of the remaining offsets.
529. Spectroscopy of 64 K red giants
ID:
ivo://CDS.VizieR/J/ApJ/735/L46
Title:
Spectroscopy of 64 K red giants
Short Name:
J/ApJ/735/L46
Date:
21 Oct 2021
Publisher:
CDS
Description:
Based on high-resolution spectra obtained with the MIKE spectrograph on the Magellan telescopes, we present detailed elemental abundances for 20 red giant stars in the outer Galactic disk, located at Galactocentric distances between 9 and 13kpc. The outer disk sample is complemented with samples of red giants from the inner Galactic disk and the solar neighborhood, analyzed using identical methods. For Galactocentric distances beyond 10kpc, we only find chemical patterns associated with the local thin disk, even for stars far above the Galactic plane. Our results show that the relative densities of the thick and thin disks are dramatically different from the solar neighborhood, and we therefore suggest that the radial scale length of the thick disk is much shorter than that of the thin disk. We make a first estimate of the thick disk scale length of L_thick_=2.0kpc, assuming L_thin_=3.8kpc for the thin disk. We suggest that radial migration may explain the lack of radial age, metallicity, and abundance gradients in the thick disk, possibly also explaining the link between the thick disk and the metal-poor bulge.
530. Spectroscopy of stars in the Galaxy's nuclear cluster
ID:
ivo://CDS.VizieR/J/ApJ/703/1323
Title:
Spectroscopy of stars in the Galaxy's nuclear cluster
Short Name:
J/ApJ/703/1323
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report on the structure of the nuclear star cluster in the innermost 0.16pc of the Galaxy as measured by the number density profile of late-type giants. Using laser guide star adaptive optics in conjunction with the integral field spectrograph, OSIRIS, at the Keck II telescope, we are able to differentiate between the older, late-type (~1Gyr) stars, which are presumed to be dynamically relaxed, and the unrelaxed young (~6Myr) population. This distinction is crucial for testing models of stellar cusp formation in the vicinity of a black hole, as the models assume that the cusp stars are in dynamical equilibrium in the black hole potential. In the survey region, we classified 60 stars as early-type (O and early B; 22 newly identified) and 74 stars as late-type (K and M; 61 newly identified). We find that contamination from young stars is significant, with more than twice as many young stars as old stars in our sensitivity range (K'<15.5) within the central arcsecond.