- ID:
- ivo://CDS.VizieR/J/A+A/372/245
- Title:
- Infrared properties of barium stars
- Short Name:
- J/A+A/372/245
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a systematic survey for IRAS associations of barium stars. A total of 155 associations were detected, and IRAS low-resolution spectra exist for 50 barium stars. We use different color-color diagrams from the visual band to 60{mu}m, relations between these colors and the spectral type, the barium intensity, and the IRAS low-resolution spectra to discuss physical properties of barium stars in the infrared. It is confirmed that most barium stars have infrared excesses in the near infrared. However, a new result of this work is that most barium stars have no excesses in the far infrared. This fact may imply that infrared excesses of barium stars are mainly due to the re-emission of energy lost from the Bond-Neff depression. It is also shown that the spectral type and the barium intensity of barium stars are not correlated with infrared colors, but may be correlated with V-K color.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/505/L5
- Title:
- Infrared radial velocities of vB10
- Short Name:
- J/A+A/505/L5
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present radial velocities of the M8V-type, very low-mass star vB 10 obtained at four different epochs between 2001 and 2008. We use high-resolution (R~20000) near-infrared (J-band) spectra taken with the NIRSPEC instrument on the Keck II telescope. Our data suggest that vB 10 shows radial velocity variability with an amplitude of ~1km/s, a result that is consistent with the recent finding of a massive planet companion around the star. More velocity measurements and a better sampling of the orbital phase are required to precisely constrain the orbital parameters and the individual masses of the pair.
- ID:
- ivo://CDS.VizieR/III/45
- Title:
- Infrared Spectra for 32 Stars
- Short Name:
- III/45
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Relative fluxes are presented for 46 spectra (30 stars plus the Sun), ranging in spectral type from A0 to M7. Spectra of seven carbon stars are included. Although some spectra cover the wavenumbers from 2500 to 8200, many spectra do not include wavenumbers less than 4000 and there are many gaps as a result of atmospheric absorption.
- ID:
- ivo://CDS.VizieR/J/ApJ/811/45
- Title:
- Infrared spectral properties of M giants
- Short Name:
- J/ApJ/811/45
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We observed a sample of 20 M giants with the Infrared Spectrograph on the Spitzer Space Telescope. Most show absorption structure at 6.6-6.8um which we identify as water vapor, and in some cases, the absorption extends from 6.4um into the SiO band at 7.5um. Variable stars show stronger H_2_O absorption. While the strength of the SiO fundamental at 8um increases monotonically from spectral class K0 to K5, the dependence on spectral class weakens in the M giants. As with previously studied samples, the M giants show considerable scatter in SiO band strength within a given spectral class. All of the stars in our sample also show OH band absorption, most noticeably in the 14-17um region. The OH bands behave much like the SiO bands, increasing in strength in the K giants but showing weaker dependence on spectral class in the M giants, and with considerable scatter. An examination of the photometric properties reveals that the V-K color may be a better indicator of molecular band strength than the spectral class. The transformation from Tycho colors to Johnson B-V color is double-valued, and neither B-V nor B_T_-V_T_ color increases monotonically with spectral class in the M giants like they do in the K giants.
- ID:
- ivo://CDS.VizieR/J/A+A/501/1059
- Title:
- Infrared spectra of 9 T dwarfs
- Short Name:
- J/A+A/501/1059
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Aims: We determine the effective temperature, surface gravity and projected rotational velocity of nine T dwarfs from the comparison of high-resolution near-infrared spectra and synthetic models, and estimate the mass and age of the objects from state-of-the-art models. Methods: We use the AMES-COND cloudless solar metallicity models provided by the PHOENIX code to match the spectra of nine T-type field dwarfs observed with the near-infrared high-resolution spectrograph NIRSPEC using ten echelle orders to cover part of the J band from 1.147 to 1.347{mu}m with a resolving power R~20000. The projected rotational velocity, effective temperature and surface gravity of the objects are determined based on the minimum root mean square of the differences between the modelled and observed relative fluxes. Estimates of the mass and age of the objects are obtained from effective temperature-surface gravity diagrams, where our results are compared with existing solar metallicity models. Results: The modelled spectra reproduce quite well the observed features for most of the T dwarfs, with effective temperatures in the range of 922-1009K, and surface gravities between 10^4.1^ and 10^4.9^cm/s^2^. Our results support the assumption of a dust free atmosphere for T dwarfs later than T5, where dust grains form and then gravitationally sediment into the low atmosphere. The modelled spectra do not accurately mimic some individual very strong lines like the KI doublet at 1.2436 and 1.2525{mu}m. Our modelled spectra does not match well the observed spectra of the two T dwarfs with earlier spectral types, namely SDSSp J125453.90-012247.4 (T2) and 2MASS J05591914-1404488 (T4.5), which is likely due to the presence of condensate clouds that are not incorporated in the models used here. By comparing our results and their uncertainties to evolutionary models, we estimate masses in the interval ~5-75M_J_ for T dwarfs later than T5, which are in good agreement with those found in the literature. We found apparent young ages that are typically between 0.1 and a few Gyr for the same T dwarfs, which is consistent with recent kinematical studies.
- ID:
- ivo://CDS.VizieR/J/AJ/162/183
- Title:
- Infrared spectra of V838 Monocerotis with SOFIA
- Short Name:
- J/AJ/162/183
- Date:
- 14 Mar 2022 06:37:38
- Publisher:
- CDS
- Description:
- Luminous Red Variables are most likely eruptions that are the outcome of stellar mergers. V838Mon is one of the best-studied members of this class, representing an archetype for stellar mergers resulting from B-type stars. As result of the merger event, "nova-like" eruptions occur driving mass loss from the system. As the gas cools considerable circumstellar dust is formed. V838Mon erupted in 2002 and is undergoing very dynamic changes in its dust composition, geometry, and infrared luminosity providing a real-time laboratory to validate mineralogical condensation sequences in stellar mergers and evolutionary scenarios. We discuss recent NASA Stratospheric Observatory for Infrared Astronomy 5-38{mu}m observations combined with archival NASA Spitzer spectra that document the temporal evolution of the freshly formed (within the last <~20yr) circumstellar material in the environs of V838Mon. Changes in the 10{mu}m spectral region are strong evidence that we are witnessing a classical dust condensation sequence expected to occur in oxygen-rich environments where alumina formation is followed by that of silicates at the temperature cools.
- ID:
- ivo://CDS.VizieR/J/AJ/144/55
- Title:
- Infrared spectroscopy of NTTS 155808-2219
- Short Name:
- J/AJ/144/55
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The young, low-mass, triple system NTTS 155808-2219 (ScoPMS 20) was previously identified as a ~17day period single-lined spectroscopic binary (SB) with a tertiary component at 0.21arcsec. Using high-resolution infrared spectra, acquired with NIRSPEC on Keck II, both with and without adaptive optics (AO), we measured radial velocities (RVs) of all three components. Reanalysis of the single-lined visible light observations, made from 1987 to 1993, also yielded RV detections of the three stars. Combining visible light and infrared data to compute the orbital solution produces orbital parameters consistent with the single-lined solution and a mass ratio of q=0.78+/-0.01 for the SB. We discuss the consistency between our results and previously published data on this system, our RV analysis with both observed and synthetic templates, and the possibility that this system is eclipsing, providing a potential method for the determination of the stars' absolute masses. Over the ~20year baseline of our observations, we have measured the acceleration of the SB's center of mass in its orbit with the tertiary. Long-term, AO imaging of the tertiary will eventually yield dynamical data useful for component mass estimates.
- ID:
- ivo://CDS.VizieR/J/AJ/153/35
- Title:
- Infrared spectroscopy of symbiotic stars. XI.
- Short Name:
- J/AJ/153/35
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Employing new infrared radial velocities, we have computed spectroscopic orbits of the cool giants in four southern S-type symbiotic systems. The orbits for two of the systems, Hen 3-461 and Hen 3-828, have been determined for the first time, while orbits of the other two, SY Mus and AR Pav, have previously been determined. For the latter two systems, we compare our results with those in the literature. The low mass of the secondary of SY Mus suggests that it has gone through a common envelope phase. Hen 3-461 has an orbital period of 2271 days, one of the longest currently known for S-type symbiotic systems. That period is very different from the orbital period proposed previously from its photometric variations. The other three binaries have periods between 600 and 700 day, values that are typical for S-type symbiotic orbits. Basic properties of the M giant components and the distance to each system are determined.
- ID:
- ivo://CDS.VizieR/J/A+A/554/A24
- Title:
- Infra-red transitions of Ca and Mg
- Short Name:
- J/A+A/554/A24
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- While solar spectra contain a lot of CaI and MgI infrared lines, no laboratory-measured spectra of these atoms have been reported for wavenumbers below 2000cm^-1^. This study reports CaI spectra in 1300-4500cm^-1^ range and MgI spectra in 1300-4500cm^-1^ range. We perform the time-resolved Fourier transform infrared spectroscopy study of a plasma created by the laser ablation of MgF_2_ and CaF_2_ targets in a vacuum. The oscillator strengths(f-values) are calculated using quantum defect theory (QDT) which shows good agreement with the available experimental and theoretical results. We report several CaI and MgI IR lines which have not been measured previously in laboratory. The recorded spectra allow to determine the excitation energies of some Ca I and Mg I states with high orbital momentum (l=4,5). We also provide a large list of QDT-calculated f-values for CaI and MgI in the range of 800-9000cm^-1^.
- ID:
- ivo://CDS.VizieR/J/AJ/160/201
- Title:
- Infrared transmission spectrum for Kepler-79d
- Short Name:
- J/AJ/160/201
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Extremely low-density planets ("super-puffs") are a small but intriguing subset of the transiting planet population. With masses in the super-Earth range (1-10M{Earth}) and radii akin to those of giant planets (>4R{Earth}), their large envelopes may have been accreted beyond the water snow line and many appear to be susceptible to catastrophic mass loss. Both the presence of water and the importance of mass loss can be explored using transmission spectroscopy. Here, we present new Hubble space telescope WFC3 spectroscopy and updated Kepler transit depth measurements for the super-puff Kepler-79d. We do not detect any molecular absorption features in the 1.1-1.7{mu}m WFC3 bandpass, and the combined Kepler and WFC3 data are consistent with a flat-line model, indicating the presence of aerosols in the atmosphere. We compare the shape of Kepler-79d transmission spectrum to predictions from a microphysical haze model that incorporates an outward particle flux due to ongoing mass loss. We find that photochemical hazes offer an attractive explanation for the observed properties of super-puffs like Kepler-79d, as they simultaneously render the near-infrared spectrum featureless and reduce the inferred envelope mass-loss rate by moving the measured radius (optical depth unity surface during transit) to lower pressures. We revisit the broader question of mass-loss rates for super-puffs and find that the age estimates and mass-loss rates for the majority of super-puffs can be reconciled if hazes move the photosphere from the typically assumed pressure of ~10mbar to ~10{mu}bar.
