- ID:
- ivo://CDS.VizieR/J/A+A/597/A10
- Title:
- South Ecliptic Pole stars radial velocities
- Short Name:
- J/A+A/597/A10
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an initial overview of the targets to be found in the 1-square-degree SEP region that was observed repeatedly by Gaia ever since its commissioning. In our representative sample, we identified one galaxy, six LMC S-stars, nine candidate chromospherically active stars, and confirmed the status of 18 LMC Carbon stars. A careful study of the 3471 epoch radial velocity measurements led us to identify 145 RV constant stars with radial velocities varying by less than 1km/s. Seventy-eight stars show significant RV scatter, while nine stars show a composite spectrum. As expected, the distribution of the RVs exhibits two main peaks that correspond to Galactic and LMC stars. By combining [Fe/H], and logg, estimates, and RV determinations, we identified 203 members of the LMC, while 51 more stars are candidate members.
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- ID:
- ivo://CDS.VizieR/J/AJ/125/2502
- Title:
- Spectral indices of Galactic halo
- Short Name:
- J/AJ/125/2502
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present our calibration of spectroscopic measures of luminosity and metallicity for halo giant candidates and give metallicities and distances for our first sample of spectroscopically confirmed giants. These giants have distances ranging from 15 to 83kpc. As surveys reach farther into the Galaxy's halo with K giant samples, identification of giants becomes more difficult. This is because the numbers of foreground halo K dwarfs rise for V magnitudes of 19-20, typical for halo giants at 100kpc. Our photometric survey uses the strength of the Mgb/H feature near 5170{AA} to weed K dwarfs out of the disk and thick disk, but we need spectroscopic measures of the strength of the Ca II K, Ca I {lambda}4227, and Mgb/H features to distinguish between the very metal-poor dwarfs and halo giants. Using a full error analysis of our spectroscopic measures, we show why a signal-to-noise ratio of ~15pixel^-1^ at Ca I {lambda}4227 and ~10 at Ca II K is needed for reliable luminosity discrimination. We use the Ca II K and Mgb features to measure metallicity in our halo giants, with typical errors (random plus systematic) of 0.3dex for [Fe/H] values from -0.8 to -3.0.
- ID:
- ivo://CDS.VizieR/J/ApJ/887/115
- Title:
- Spectra of 28 stars in Price-Whelan 1 association
- Short Name:
- J/ApJ/887/115
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report spectroscopic measurements of stars in the recently discovered young stellar association Price-Whelan 1 (PW1), which was found in the vicinity of the Leading Arm (LA) of the Magellanic Stream (MS). We obtained Magellan+MIKE high-resolution spectra of the 28 brightest stars in PW 1 and used The Cannon to determine their stellar parameters. We find that the mean metallicity of PW1 is [Fe/H]=-1.23 with a small scatter of 0.06dex and the mean RV is V_hel_=276.7km/s with a dispersion of 11.0km/s. Our results are consistent in T_eff_, logg, and [Fe/H] with the young and metal-poor characteristics (116Myr and [Fe/H]=-1.1) determined for PW1 from our discovery paper. We find a strong correlation between the spatial pattern of the PW1 stars and the LA II gas with an offset of -10.15{deg} in L_MS_ and +1.55{deg} in B_MS_. The similarity in metallicity, velocity, and spatial patterns indicates that PW1 likely originated in LA II. We find that the spatial and kinematic separation between LA II and PW1 can be explained by ram pressure from Milky Way (MW) gas. Using orbit integrations that account for the LMC and MW halo and outer disk gas, we constrain the halo gas density at the orbital pericenter of PW1 to be n_halo_(17kpc)=2.7_-2.0_^+3.4^x10^-3^atoms/cm^3^ and the disk gas density at the midplane at 20kpc to be n_disk_(20kpc,0)=6.0_-2.0_^+1.5^x10^-2^atoms/cm^3^. We, therefore, conclude that PW 1 formed from the LA II of the MS, making it a powerful constraint on the MW-Magellanic interaction.
- ID:
- ivo://CDS.VizieR/V/65
- Title:
- Spectroscopically Selected Halo K Giants
- Short Name:
- V/65
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The catalog results from a survey for distant Field K giants in the Galactic halo made for purposes of locating a chemically and kinematically unbiased sample out to about 25 kpc from the Sun. The motivation for the study and sample selection are outlined by Ratnatunga & Freeman (1985ApJ...291..260R), while details and analysis of the results will be found in Ratnatunga & Freeman (1989). Three high-galactic latitude fields each of 20 square degrees, designated by their Selected-Area identifications, include the following: SA 141 (l=240,b=-85); SA 189 (277, -50); and SA 127 (272, +38), and have the apparent magnitude range 13 < V < 16 and color range (B-V) > 0.9. Stars were selected from PDS photographic photometry of Schmidt plates (see Ratnatunga 1983, catalog II/121). K-giant selection used the Mgb+MgH feature at 5100A from digital image analysis of PDS scans of ESO 1-m Schmidt telescope objective-prism spectra with 450 A/mm at H-gamma resolution on IIIa-J plates exposed through a Schott GG475 filter. Luminosity confirmation, line-of-sight velocities, and metallicity were determined from 2-A resolution slit spectra taken with the 4-m Anglo- Australian and 1.9-m Mount Stromlo telescopes. Cross identifications exist for some stars in the SA 141 SGP field only.
- ID:
- ivo://CDS.VizieR/J/A+A/547/A91
- Title:
- Spectroscopic analysis of 348 red giants
- Short Name:
- J/A+A/547/A91
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present basic atmospheric parameters (Teff, logg, vt, and [Fe/H]) as well as luminosities, masses, radii, and absolute radial velocities for 348 stars, presumably giants, from the ~1000 star sample observed within the Penn State-Torun Centre for Astronomy Planet Search (PTPS) with the High Resolution Spectrograph of the 9.2m Hobby-Eberly Telescope. The stellar parameters (luminosities, masses, radii) are key to properly interpreting newly discovered low-mass companions, while a systematic study of the complete sample will create a basis for future statistical considerations concerning the appearance of low-mass companions around evolved low- and intermediate-mass stars.
- ID:
- ivo://CDS.VizieR/J/ApJ/866/22
- Title:
- Spectroscopic analysis of Tuc III stream
- Short Name:
- J/ApJ/866/22
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a spectroscopic study of the tidal tails and core of the Milky Way satellite Tucana III, collectively referred to as the Tucana III stream, using the 2dF+AAOmega spectrograph on the Anglo-Australian Telescope and the IMACS spectrograph on the Magellan Baade Telescope. In addition to recovering the brightest nine previously known member stars in the Tucana III core, we identify 22 members in the tidal tails. We observe strong evidence for a velocity gradient of 8.0+/-0.4km/s/deg over at least 3{deg} on the sky. Based on the continuity in velocity, we confirm that the Tucana III tails are real tidal extensions of Tucana III. The large velocity gradient of the stream implies that Tucana III is likely on a radial orbit. We successfully obtain metallicities for four members in the core and 12 members in the tails. We find that members close to the ends of the stream tend to be more metal-poor than members in the core, indicating a possible metallicity gradient between the center of the progenitor halo and its edge. The spread in metallicity suggests that the progenitor of the Tucana III stream is likely a dwarf galaxy rather than a star cluster. Furthermore, we find that with the precise photometry of the Dark Energy Survey data, there is a discernible color offset between metal-rich disk stars and metal-poor stream members. This metallicity-dependent color offers a more efficient method to recognize metal-poor targets and will increase the selection efficiency of stream members for future spectroscopic follow-up programs on stellar streams.
- 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.
- ID:
- ivo://CDS.VizieR/J/ApJ/770/43
- Title:
- Spectroscopic [Fe/H] of Kepler stars
- Short Name:
- J/ApJ/770/43
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- It has been shown that F, G, and early K dwarf hosts of Neptune-sized planets are not preferentially metal-rich. However, it is less clear whether the same holds for late K and M dwarf planet hosts. We report metallicities of Kepler targets and candidate transiting planet hosts with effective temperatures below 4500K. We use new metallicity calibrations to determine [Fe/H] from visible and near-infrared spectra. We find that the metallicity distribution of late K and M dwarfs monitored by Kepler is consistent with that of the solar neighborhood. Further, we show that hosts of Earth- to Neptune-sized planets have metallicities consistent with those lacking detected planets and rule out a previously claimed 0.2dex offset between the two distributions at 6{sigma} confidence. We also demonstrate that the metallicities of late K and M dwarfs hosting multiple detected planets are consistent with those lacking detected planets. Our results indicate that multiple terrestrial and Neptune-sized planets can form around late K and M dwarfs with metallicities as low as 0.25 solar. The presence of Neptune-sized planets orbiting such low-metallicity M dwarfs suggests that accreting planets collect most or all of the solids from the disk and that the potential cores of giant planets can readily form around M dwarfs. The paucity of giant planets around M dwarfs compared to solar-type stars must be due to relatively rapid disk evaporation or a slower rate of planet accretion, rather than insufficient solids to form a core.
- ID:
- ivo://CDS.VizieR/J/AJ/152/207
- Title:
- Spectroscopic Indicators in SeisMic Archive (SISMA)
- Short Name:
- J/AJ/152/207
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We created a large database of physical parameters and variability indicators by fully reducing and analyzing the large number of spectra taken to complement the asteroseismic observations of the COnvection, ROtation and planetary Transits (CoRoT) satellite. 7103 spectra of 261 stars obtained with the ESO echelle spectrograph HARPS have been stored in the VO-compliant database Spectroscopic Indicators in a SeisMic Archive (SISMA), along with the CoRoT photometric data of the 72 CoRoT asteroseismic targets. The remaining stars belong to the same variable classes of the CoRoT targets and were observed to better characterize the properties of such classes. Several useful variability indicators (mean line profiles, indices of differential rotation, activity and emission lines) together with vsini and radial-velocity measurements have been extracted from the spectra. The atmospheric parameters T_eff_,logg, and [Fe/H] have been computed following a homogeneous procedure. As a result, we fully characterize a sample of new and known variable stars by computing several spectroscopic indicators, also providing some cases of simultaneous photometry and spectroscopy.
- ID:
- ivo://CDS.VizieR/J/A+A/622/A110
- Title:
- Spectroscopic membership for NGC 3532
- Short Name:
- J/A+A/622/A110
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- NGC 3532 is an extremely rich open cluster embedded in the Galactic disc, hitherto lacking a comprehensive, documented membership list. We provide membership probabilities from new radial velocity observations of solar-type and low-mass stars in NGC 3532, in part as a prelude to a subsequent study of stellar rotation in the cluster. Using extant optical and infra-red photometry we constructed a preliminary photometric membership catalogue, consisting of 2230 dwarf and turn-off stars. We selected 1060 of these for observation with the AAOmega spectrograph at the 3.9m Anglo-Australian Telescope and 391 stars for observations with the Hydra-South spectrograph at the 4m Victor Blanco Telescope, obtaining spectroscopic observations over a decade for 145 stars. We measured radial velocities for our targets through cross-correlation with model spectra and standard stars, and supplemented them with radial velocities for 433 additional stars from the literature. We also measured logg, Teff, and [Fe/H] from the AAOmega spectra. The radial velocity distribution emerging from the observations is centred at 5.43+/-0.04km/s and has a width (standard deviation) of 1.46km/s. Together with proper motions from Gaia DR2 we find 660 exclusive members, of which five are likely binary members. The members are distributed across the whole cluster sequence, from giant stars to M dwarfs, making NGC~3532 one of the richest Galactic open clusters known to date, on par with the Pleiades. From further spectroscopic analysis of 153 dwarf members we find the metallicity to be marginally sub-solar, with [Fe/H]=-0.07+/-0.10. We confirm the extremely low reddening of the cluster, E_B-V_=0.034+/-0.012mag, despite its location near the Galactic plane. Exploiting trigonometric parallax measurements from Gaia DR2 we find a distance of 484^+35^_-30_pc [(m-M)_0_=8.42+/-0.14mag]. Based on the membership we provide an empirical cluster sequence in multiple photometric passbands. A comparison of the photometry of the measured cluster members with several recent model isochrones enables us to confirm the 300Myr cluster age. However, all of the models evince departures from the cluster sequence in particular regions, especially in the lower mass range.
