- ID:
- ivo://CDS.VizieR/J/ApJ/694/L144
- Title:
- Spectroscopic study of Leo V dSph
- Short Name:
- J/ApJ/694/L144
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a spectroscopic study of Leo V, a recently discovered satellite of the Milky Way (MW). From stellar spectra obtained with the MMT/Hectochelle spectrograph we identify seven likely members of Leo V. Five cluster near the Leo V center (R<3') and have a velocity dispersion of 2.4^+2.4^_1.4_km/s. The other two likely members lie near each other but far from the center (R~13'~700pc) and inflate the global velocity dispersion to 3.7^+2.3^_1.4_km/s.
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- ID:
- ivo://CDS.VizieR/J/AJ/135/1117
- Title:
- Spectroscopic study of red giants in M15
- Short Name:
- J/AJ/135/1117
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- High-resolution spectra of 110 selected red giant stars in the globular cluster M15 (NGC 7078) were obtained with Hectochelle at the MMT telescope in 2005 May, 2006 May, and 2006 October. Echelle orders containing H{alpha} and CaII H&K are used to identify emission and line asymmetries characterizing motions in the extended atmospheres. Emission in H{alpha} is detected to a luminosity of log(L/L_{sun}_)=2.36, in this very metal-deficient cluster, comparable to other studies, suggesting that the appearance of emission wings is independent of stellar metallicity. The faintest stars showing H{alpha} emission appear to lie on the asymptotic giant branch (AGB) in M15. A line-bisector technique for H{alpha} reveals outflowing velocities in all stars brighter than log(L/L_{sun}_)=2.5, and this outflow velocity increases with stellar luminosity, indicating the mass outflow increases smoothly with luminosity. Many stars lying low on the AGB show exceptionally high outflow velocities (up to 10-15km/s) and more velocity variability (up to 6-8km/s) than red giant branch (RGB) stars of similar apparent magnitude. High velocities in M15 may be related to the low cluster metallicity. Dusty stars identified from Spitzer Space Telescope infrared photometry as AGB stars are confirmed as cluster members by radial velocity measurements, yet their H{alpha} profiles are similar to those of RGB stars without dust. If substantial mass loss creates the circumstellar shell responsible for infrared emission, such mass loss must be episodic.
- ID:
- ivo://CDS.VizieR/J/MNRAS/397/1748
- Title:
- Spectroscopic study of Segue 2
- Short Name:
- J/MNRAS/397/1748
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We announce the discovery of a new Milky Way satellite Segue 2 found in the data of the Sloan Extension for Galactic Understanding and Exploration (SEGUE). We followed this up with deeper imaging and spectroscopy on the Multiple Mirror Telescope (MMT). From this, we derive a luminosity of Mv=-2.5, a half-light radius of 34pc and a systemic velocity of ~-40km/s. Our data also provide evidence for a stream around Segue 2 at a similar heliocentric velocity, and the SEGUE data show that it is also present in neighbouring fields. We resolve the velocity dispersion of Segue 2 as 3.4km/s and the possible stream as ~7km/s. This object shows points of comparison with other recent discoveries, Segue 1, Boo II and Coma. We speculate that all four objects may be representatives of a population of satellites of satellites - survivors of accretion events that destroyed their larger but less dense parents. They are likely to have formed at redshifts z>10 and are good candidates for fossils of the reionization epoch.
- ID:
- ivo://CDS.VizieR/J/A+A/382/118
- Title:
- Spectroscopic sub-systems in multiple stars
- Short Name:
- J/A+A/382/118
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A large sample of visual multiples of spectral types F5-M has been surveyed for the presence of spectroscopic sub-systems. In table 1 we provide basic identifiers for the components or their combinations, average radial velocities, parameters of correlation dips and analysis of the velocity variability and physical relation. Notes contain comments and additional identifiers. Individual radial velocities yet unpublished are listed in table 2. Table 6 is extracted from the Multiple Star Catalog (Cat. <J/A+AS/124/75>) for the analysis of the statistics of spectroscopic+visual multiple stellar systems.
- ID:
- ivo://CDS.VizieR/J/AJ/112/1489
- Title:
- Spectroscopic survey for binaries in NGC 5053
- Short Name:
- J/AJ/112/1489
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We carried our a radial velocity survey for spectroscopic binaries in the low-density globular cluster NGC 5053. Our sample contains a total of 77 cluster member giant and subgiant stars with visual magnitudes of 14.5-18.6. Of These 77 stars, 66 stars have on average of 3-4 measurements with a total of 236 velocities. A typical velocity error per measurement is 13km/s. The stars in our sample are spatially distributed from the cluster center out to 10arcmin in radius (4.5 core radii). Among theses 66 stars with multiple velocity measurements, we discovered 6 spectroscopic binary candidates.
- ID:
- ivo://CDS.VizieR/J/A+A/420/183
- Title:
- Spectroscopic survey in solar neighborhood
- Short Name:
- J/A+A/420/183
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the results of a high-resolution spectroscopic survey of all the stars more luminous than M_V_=6.5mag within 14.5pc from the Sun. The Hipparcos catalog's completeness limits guarantee that our survey is comprehensive and free from some of the selection effects in other samples of nearby stars. The resulting spectroscopic database, which we have made publicly available, includes spectra for 118 stars obtained with a resolving power of R~50000, continuous spectral coverage between ~362-921nm, and typical signal-to-noise ratios in the range 150-600. We derive stellar parameters and perform a preliminary abundance and kinematic analysis of the F-G-K stars in the sample. The inferred metallicity ([Fe/H]) distribution is centered at about -0.1dex, and shows a standard deviation of 0.2dex.
- ID:
- ivo://CDS.VizieR/J/ApJ/647/303
- Title:
- Spectroscopic survey of hypervelocity stars
- Short Name:
- J/ApJ/647/303
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We discuss our targeted search for hypervelocity stars (HVSs), stars traveling with velocities so extreme that dynamical ejection from a massive black hole is their only suggested origin. Our survey, now half-complete, has successfully identified a total of four probable HVSs plus a number of other unusual objects. Here we report the two most recently discovered HVSs: SDSS J110557.45+093439.5 and possibly SDSS J113312.12+010824, traveling with Galactic rest-frame velocities at least +508+/-12 and 418+/-10km/s, respectively.
- ID:
- ivo://CDS.VizieR/J/AJ/130/1871
- Title:
- Spectroscopic survey of M dwarfs
- Short Name:
- J/AJ/130/1871
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have constructed a sample of M dwarfs out to a distance of ~100pc. This sample of 605 stars (574 M dwarfs and 31 K dwarfs) have been spectroscopically observed, yielding spectral types, radial velocities, H{alpha} equivalent widths, and molecular band indices. Photometric observations have been compiled, with photographic plates providing RI magnitudes and JHKs magnitudes from Two Micron All Sky Survey (Cat. <II/246>) observations. Proper motions were determined by a match to USNO-B (Cat. <I/284>), and distances were computed employing a spectroscopic parallax, allowing the computation of UVW space motions.
- ID:
- ivo://CDS.VizieR/J/A+A/504/829
- Title:
- Spectroscopic survey of youngest field stars
- Short Name:
- J/A+A/504/829
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first results of an ambitious ground-based observation programme conducted on 1-4m class telescopes. Our sample consists of 1097 active and presumably young stars, all of them being optical (Tycho Catalogue) counterparts of ROSAT All- Sky Survey X-ray sources in the northern hemisphere. In this paper, we concentrate on the optically brightest (VT<=9.5m) candidates (704 objects).We acquired high-resolution optical spectroscopy in the H{alpha} and/or lithium spectral regions for 426 of such stars without relevant data in the literature. We describe the star sample and the observations and we start to discuss the physical properties of the investigated stars.
- ID:
- ivo://CDS.VizieR/J/A+A/612/A96
- Title:
- Spectroscopic survey of youngest field stars II.
- Short Name:
- J/A+A/612/A96
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Star formation in the solar neighborhood is mainly traced by young stars in open clusters, associations, and in the field, which can be identified, for example, by their X-ray emission. The determination of stellar parameters for the optical counterparts of X-ray sources is crucial for a full characterization of these stars. This work extends the spectroscopic study of the RasTyc sample, obtained by the cross-correlation of the TYCHO and ROSAT All-Sky Survey catalogs, to stars fainter than V=9.5mag and aims to identify sparse populations of young stars in the solar neighborhood. We acquired 625 high-resolution spectra for 443 presumably young stars with four different instruments in the northern hemisphere. The radial and rotational velocity (vsini) of our targets were measured by means of the cross-correlation technique, which is also helpful to discover single-lined (SB1), double-lined spectroscopic binaries (SB2), and multiple systems. We used the code ROTFIT to perform an MK spectral classification and to determine the atmospheric parameters (Teff, logg, [Fe/H]) and and vsini of the single stars and SB1 systems. For these objects, we used the spectral subtraction of slowly rotating templates to measure the equivalent widths of the H{alpha} and LiI-6708A lines, which enabled us to derive their chromospheric activity level and lithium abundance. We made use of Gaia DR1 parallaxes and proper motions to locate the targets in the HR diagram and to compute the space velocity components of the youngest objects. We find a remarkable percentage (at least 35%) of binaries and multiple systems. On the basis of the lithium abundance, the sample of single stars and SB1 systems appears to be mostly (about 60%) composed of stars younger than the members of the UMa cluster. The remaining sources are in the age range between the UMa and Hyades clusters (about 20%) or older (20%). In total, we identify 42 very young (PMS-like) stars, which lie above or very close to the Pleiades upper envelope of the lithium abundance. A significant percentage (about 12%) of evolved stars (giants and subgiants) is also present in our sample. Some of these stars are also lithium rich (A(Li)>1.4).
