- ID:
- ivo://CDS.VizieR/J/A+A/598/A79
- Title:
- 10 Leo in YJ, H, K, L and M bands spectra
- Short Name:
- J/A+A/598/A79
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- High resolution stellar spectral atlases are valuable resources to astronomy. They are rare in the 1-5{mu}m region for historical reasons, but once available, high resolution atlases in this part of the spectrum will aid the study of a wide range of astrophysical phenomena. The aim of the CRIRES-POP project is to produce a high resolution near-infrared spectral library of stars across the H-R diagram. The aim of this paper is to present the fully reduced spectrum of the K giant 10 Leo that will form the basis of the first atlas within the CRIRES-POP library, to provide a full description of the data reduction processes involved, and to provide an update on the CRIRES-POP project. All CRIRES-POP targets were observed with almost 200 different observational settings of CRIRES on the ESO Very Large Telescope, resulting in a basically complete coverage of its spectral range as accessible from the ground. We reduced the 10 Leo spectra with the CRIRES pipeline, corrected the wavelength solution and removed telluric absorption with Molecfit, then resampled the spectra to a common wavelength scale, shifted to rest wavelengths, flux normalised, and median combined them into one final data product. We present the fully reduced, high resolution, near-infrared spectrum of 10 Leo. This is also the first complete spectrum from the CRIRES instrument. The spectrum is available online. The first CRIRES-POP spectrum has exceeded our quality expectations and will form the centre of a state-of-the-art stellar atlas. This first CRIRES-POP atlas will soon be available, and further atlases will follow. All CRIRES-POP data products will be freely and publicly available online.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/639/A7
- Title:
- Li-rich and non-Li-rich K giants RVs
- Short Name:
- J/A+A/639/A7
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The origin of the Li-rich K giants is still highly debated. Here, we investigate the incidence of binarity among this family from a nine-year radial-velocity monitoring of a sample of 11 Li-rich K giants using the HERMES spectrograph attached to the 1.2m Mercator Telescope. A sample of 13 non-Li-rich giants (8 of them being surrounded by dust according to IRAS, WISE, and ISO data) was monitored alongside. When compared to the binary frequency in a reference sample of 190K giants (containing 17.4% of definite spectroscopic binaries - SB - and 6.3% of possible spectroscopic binaries - SB?), the binary frequency appears normal among the Li-rich giants (2/11 definite binaries plus 2 possible binaries, or 18.2% SB + 18.2% SB?), after taking account of the small sample size through the hypergeometric probability distribution. Therefore, there appears to be no causal relationship between Li enrichment and binarity. Moreover, there is no correlation between Li enrichment and the presence of circumstellar dust, and the only correlation that could be found between Li enrichment and rapid rotation is that the most Li-enriched K giants appear to be fast-rotating stars. However, among the dusty K giants, the binary frequency is much higher (4/8 definite binaries plus 1 possible binary). The remaining 3 dusty K giants suffer from a radial-velocity jitter, as is expected for the most luminous K giants, which these are.
- ID:
- ivo://CDS.VizieR/J/A+A/613/A63
- Title:
- Lithium content for 148 Pleiades stars
- Short Name:
- J/A+A/613/A63
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The evolution of lithium abundance over a star's lifetime is indicative of transport processes operating in the stellar interior. Aims. We revisit the relationship between lithium content and rotation rate previously reported for cool dwarfs in the Pleiades cluster. Methods. We derive new LiI 670.8nm equivalent width measurements from high-resolution spectra obtained for low-mass Pleiades members. We combine these new measurements with previously published ones, and use the Kepler/K2 rotational periods recently derived for Pleiades cool dwarfs to investigate the lithium-rotation connection in this 125Myr-old cluster. Results. The new data confirm the correlation between lithium equivalent width and stellar spin rate for a sample of 51 early K-type members of the cluster, where fast rotating stars are systematically lithium-rich compared to slowly rotating ones. The correlation is valid for all stars over the (J-Ks) color range 0.50-0.70mag, corresponding to a mass range from about 0.75 to 0.90M_{sun}_, and may extend down to lower masses. Conclusions. We argue that the dispersion in lithium equivalent widths observed for cool dwarfs in the Pleiades cluster reflects an intrinsic scatter in lithium abundances, and suggest that the physical origin of the lithium dispersion pattern is to be found in the pre-main sequence rotational history of solar-type stars.
- ID:
- ivo://CDS.VizieR/J/ApJ/886/19
- Title:
- Ly{alpha} obs. of low-mass stars Ross 825 & 1044
- Short Name:
- J/ApJ/886/19
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The discovery of habitable zone (HZ) planets around low-mass stars has highlighted the need for a comprehensive understanding of the radiation environments in which such planets reside. Of particular importance is knowledge of the far-ultraviolet (FUV) radiation, as low-mass stars are typically much more active than solar-type stars and the proximity of their HZs can be one-tenth the distance. The vast majority of the flux emitted by low-mass stars at FUV wavelengths occurs in the Ly{alpha} line at 1216 {AA}. However, measuring a low-mass star's Ly{alpha} emission directly is almost always impossible because of the contaminating effects of interstellar hydrogen and geocoronal airglow. We observed Ross825 (K3) and Ross1044 (M0), two stars with exceptional radial velocities, with the Space Telescope Imaging Spectrograph on board the Hubble Space Telescope. Their radial velocities resulted in significant line shifts, allowing for a more complete view of their Ly{alpha} line profiles. We provide an updated relation between effective temperature and Ly{alpha} flux using Gaia DR2 astrometry as well as updated, model-independent relationships between Ly{alpha} flux and UV flux measurements from the Galaxy Evolution Explorer (GALEX) for low-mass stars. These new relations, in combination with GALEX's considerable spatial coverage, provide substantial predictive power for the Ly{alpha} environments for thousands of nearby, low-mass stars.
- ID:
- ivo://CDS.VizieR/J/A+A/598/A43
- Title:
- 2MASS J16042165-2130284 high-contrast images
- Short Name:
- J/A+A/598/A43
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The large cavities observed in the dust and gas distributions of transition disks may be explained by planet-disk interactions. At 145pc, 2MASS J16042165-2130284 (J1604) is a 5-12Myr old transitional disk with different gap sizes in the mm- and micron-sized dust distributions (outer edges at 79 and at 63AU, respectively). Its ^12^CO emission shows a 30 au cavity. This radial structure suggests that giant planets are sculpting this disk. We aim to constrain the masses and locations of plausible giant planets around J1604. We observed J1604 with the Spectro-Polarimetric High-contrast Exoplanet REsearch (SPHERE) at the Very Large Telescope (VLT), in IRDIFS_EXT, pupil-stabilized mode, obtaining YJH- band images with the integral field spectrograph (IFS) and K1K2-band images with the Infra-Red Dual-beam Imager and Spectrograph (IRDIS). The dataset was processed exploiting the angular differential imaging (ADI) technique with high-contrast algorithms. Our observations reach a contrast of {Delta}K, {Delta}YH~12mag from 0.15" to 0.80" (~22 to 115AU), but no planet candidate is detected. The disk is directly imaged in scattered light at all bands from Y to K, and it shows a red color. This indicates that the dust particles in the disk surface are mainly >~0.3um-sized grains. We confirm the sharp dip/decrement in scattered light in agreement with polarized light observations. Comparing our images with a radiative transfer model we argue that the southern side of the disk is most likely the nearest. This work represents the deepest search yet for companions around J1604. We reach a mass sensitivity of >~2-3M_Jup_ from ~22 to ~115AU according to a hot start scenario. We propose that a brown dwarf orbiting inside of ~15AU and additional Jovian planets at larger radii could account for the observed properties of J1604 while explaining our lack of detection.
- ID:
- ivo://CDS.VizieR/J/A+A/564/A90
- Title:
- M subdwarfs VLT/UVES high resolution spectra
- Short Name:
- J/A+A/564/A90
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- M subdwarfs are metal poor and cool stars. They are important probes of the old galactic populations. However, they remain elusive due to their low luminosity. Observational and modeling efforts are required to fully understand their physics and to investigate the effects of metallicity in their cool atmospheres. We perform a detailed study of a sample of subdwarfs to determine their stellar parameters and constrain the stat-of-the art atmospheric models. We present UVES/VLT high resolution spectra of three late-K subdwarfs and 18 M subdwarfs. Our atlas covers the optical region from 6400{AA} up to the near infrared at 8900{AA}. We show spectral details of cool atmospheres at very high resolution (R~40000) and compare with synthetic spectra computed from the recent BT-Settl atmosphere models. Our comparison shows that molecular features (TiO, VO, CaH), and atomic features (FeI, TiI, NaI, KI) are well fitted by current models. We produce an effective temperature versus spectral type relation all over the subdwarf spectral sequence. Thanks to the high resolution of our spectra, we perform a detailed comparison of line profiles of individual elements such as FeI, CaII, TiI, and are able to determine accurate metallicities of these stars. These determinations contribute to calibrate the relation between metallicity and molecular band strength indices from low-resolution spectra. This work shows that the new generation of models are able to reproduce various spectral features of M subdwarfs. Working with these high resolution spectra allowed us to disentangle the atmospheric parameters (effective temperature, gravity, metallicity), which is not possible when using low resolution spectroscopy or photometry.
- ID:
- ivo://CDS.VizieR/J/A+A/619/A81
- Title:
- Multiplicity among solar-type stars. IV.
- Short Name:
- J/A+A/619/A81
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A sample of 261 K-type stars was observed with the spectrovelocimeter CORAVEL. The stars with a variable radial velocity were detected and the orbital elements of the spectroscopic binaries were derived.
- ID:
- ivo://CDS.VizieR/III/25A
- Title:
- Na, Mg, Ca abundances in K-type giants
- Short Name:
- III/25A
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Narrow-band photometric measures of the strengths of the Mg b, Ca triplet, and Na D lines on 312 G and K type giant stars have been analysed with a model atmosphere technique to determine abundances of Mg, Ca and Na.
- ID:
- ivo://CDS.VizieR/J/AJ/161/295
- Title:
- Obs. with Differential Speckle Survey Instrument. X.
- Short Name:
- J/AJ/161/295
- Date:
- 09 Mar 2022 22:00:00
- Publisher:
- CDS
- Description:
- This paper details speckle observations of binary stars taken at the Lowell Discovery Telescope, the WIYN telescope, and the Gemini telescopes between 2016 January and 2019 September. The observations taken at Gemini and Lowell were done with the Differential Speckle Survey Instrument (DSSI), and those done at WIYN were taken with the successor instrument to DSSI at that site, the NN-EXPLORE Exoplanet Star and Speckle Imager (NESSI). In total, we present 378 observations of 178 systems, and we show that the uncertainty in the measurement precision for the combined data set is ~2mas in separation, ~1{deg}-2{deg} in position angle depending on the separation, and ~0.1mag in magnitude difference. Together with data already in the literature, these new results permit 25 visual orbits and one spectroscopic- visual orbit to be calculated for the first time. In the case of the spectroscopic-visual analysis, which is done on the ternary star HD173093, we calculate masses with a precision of better than 1% for all three stars in that system. Twenty-one of the visual orbits calculated have a K-dwarf as the primary star; we add these to the known orbits of K-dwarf primary stars and discuss the basic orbital properties of these stars at this stage. Although incomplete, the data that exist so far indicate that binaries with K-dwarf primaries tend not to have low-eccentricity orbits at separations of one to a few tens of astronomical units, that is, on solar system scales.
- ID:
- ivo://CDS.VizieR/J/ApJ/702/403
- Title:
- Photometric observations of V1197 Orionis
- Short Name:
- J/ApJ/702/403
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- V1197 Orionis light curves from a long-term observing program for red giant binaries show ellipsoidal variation of small amplitude in the V and R_C_ bands, although not clearly in U and B. Eclipses are not detected. All four bands show large irregular intrinsic variations, including fleeting quasi-periodicities identified by power spectra, that degrade analysis and may be caused by dynamical tides generated by orbital eccentricity. To deal with the absence of eclipses and consequent lack of astrophysical and geometrical information, direct use is made of the Hipparcos parallax distance while the V and R_C_ light curves and (older) radial velocity curves are analyzed simultaneously in terms of absolute flux. The red giant's temperature is estimated from new spectra. The dim companion has not been observed or discussed in the literature but most solutions find its mass to be well below that of the red giant. Solutions show red giant masses that are too low for evolution to the red giant stage within the age of the Galaxy, although that result is probably an artifact of the intrinsic brightness fluctuations.
