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751. Indo-US library of coude feed stellar spectra
ID:
ivo://CDS.VizieR/J/ApJS/152/251
Title:
Indo-US library of coude feed stellar spectra
Short Name:
J/ApJS/152/251
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have obtained spectra for 1273 stars using the 0.9m coude feed telescope at Kitt Peak National Observatory. This telescope feeds the coude spectrograph of the 2.1m telescope. The spectra have been obtained with the No.5 camera of the coude spectrograph and a Loral 3Kx1K CCD. Two gratings have been used to provide spectral coverage from 3460 to 9464{AA}, at a resolution of ~1{AA} FWHM and at an original dispersion of 0.44{AA}/pix. For 885 stars we have complete spectra over the entire 3460 to 9464{AA} wavelength region (neglecting small gaps of less than 50{AA}), and partial spectral coverage for the remaining stars. The 1273 stars have been selected to provide broad coverage of the atmospheric parameters T_eff_, logg, and [Fe/H], as well as spectral type. The goal of the project is to provide a comprehensive library of stellar spectra for use in the automated classification of stellar and galaxy spectra and in galaxy population synthesis. In this paper we discuss the characteristics of the spectral library, viz., details of the observations, data reduction procedures, and selection of stars. We also present a few illustrations of the quality and information available in the spectra. The first version of the complete spectral library is now publicly available from the National Optical Astronomy Observatory (NOAO) via ftp and http, at http://www.noao.edu/cflib .
752. Infrared absorbance of water H_2_O/H_2_O_2_ ice
ID:
ivo://CDS.VizieR/J/ApJ/743/131
Title:
Infrared absorbance of water H_2_O/H_2_O_2_ ice
Short Name:
J/ApJ/743/131
Date:
21 Oct 2021
Publisher:
CDS
Description:
Recent surface chemistry experiments have shown that the hydrogenation of molecular oxygen on interstellar dust grains is a plausible formation mechanism, via hydrogen peroxide (H_2_O_2_), for the production of water (H_2_O) ice mantles in the dense interstellar medium. Theoretical chemistry models also predict the formation of a significant abundance of H_2_O_2_ ice in grain mantles by this route. At their upper limits, the predicted and experimental abundances are sufficiently high that H_2_O_2_ should be detectable in molecular cloud ice spectra. To investigate this further, laboratory spectra have been obtained for H_2_O_2_/H_2_O ice films between 2.5 and 200um, from 10 to 180K, containing 3%, 30%, and 97% H_2_O_2_ ice. Integrated absorbances for all the absorption features in low-temperature H_2_O_2_ ice have been derived from these spectra. For identifying H_2_O_2_ ice, the key results are the presence of unique features near 3.5, 7.0, and 11.3um. Comparing the laboratory spectra with the spectra of a group of 24 protostars and field stars, all of which have strong H_2_O ice absorption bands, no absorption features are found that can definitely be identified with H_2_O_2_ ice. In the absence of definite H_2_O_2_ features, the H_2_O_2_ abundance is constrained by its possible contribution to the weak absorption feature near 3.47um found on the long-wavelength wing of the 3um H_2_O ice band. This gives an average upper limit for H_2_O_2_, as a percentage of H_2_O, of 9%+/-4%. This is a strong constraint on parameters for surface chemistry experiments and dense cloud chemistry models.
753. Infrared photometry of all known members in Taurus
ID:
ivo://CDS.VizieR/J/ApJ/784/126
Title:
Infrared photometry of all known members in Taurus
Short Name:
J/ApJ/784/126
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have compiled photometry at 3.4, 4.6, 12, and 22{mu}m from the all-sky survey performed by the Wide-field Infrared Survey Explorer (WISE) for all known members of the Taurus complex of dark clouds. Using these data and photometry from the Spitzer Space Telescope, we have identified members with infrared excess emission from circumstellar disks and have estimated the evolutionary stages of the detected disks, which include 31 new full disks and 16 new candidate transitional, evolved, evolved transitional, and debris disks. We have also used the WISE All-Sky Source Catalog to search for new disk-bearing members of Taurus based on their red infrared colors. Through optical and near-infrared spectroscopy, we have confirmed 26 new members with spectral types of M1-M7. The census of disk-bearing stars in Taurus should now be largely complete for spectral types earlier than ~M8(M{>~}0.03M_{sun}_).
754. Infrared properties of barium stars
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.
755. Infrared Spectra for 32 Stars
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.
756. Infrared spectral properties of M giants
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.
757. Infrared spectra of 9 T dwarfs
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.
758. Infrared spectroscopy of symbiotic stars. XI.
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.
759. Infrared transmission spectrum for Kepler-79d
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.
760. Inner/outer HII regions: galaxy sample
ID:
ivo://CDS.VizieR/J/A+A/609/A102
Title:
Inner/outer HII regions: galaxy sample
Short Name:
J/A+A/609/A102
Date:
21 Oct 2021
Publisher:
CDS
Description:
Using integral field spectroscopy (IFS) observations we aim to perform a systematic study and comparison of two inner and outer HII regions samples. The spatial resolution of the IFS, the number of objects and the homogeneity and coherence of the observations allow a complete characterization of the main observational properties and differences of the regions. We analyzed a sample of 725 inner HII regions and a sample of 671 outer HII regions, all of them detected and extracted from the observations of a sample of 263 nearby, isolated, spiral galaxies observed by the CALIFA survey. We find that inner HII regions show smaller equivalent widths, greater extinction and luminosities, along with greater values of [NII] {lambda}6583/H{alpha} and [OII] {lambda}3727/[OIII] {lambda}5007 emission-line ratios, indicating higher metallicities and lower ionization parameters. Inner regions have also redder colors and higher photometric and ionizing masses, although Mion/Mphot is slightly higher for the outer regions. This work shows important observational differences between inner and outer HII regions in star forming galaxies not previously studied in detail. These differences indicate that inner regions have more evolved stellar populations and are in a later evolution state with respect to outer regions, which goes in line with the inside-out galaxy formation paradigm.