- ID:
- ivo://CDS.VizieR/J/ApJS/238/29
- Title:
- IGRINS spectral library
- Short Name:
- J/ApJS/238/29
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a library of high-resolution (R~45000) and high signal-to-noise ratio (S/N>=200) near-infrared spectra for stars of a wide range of spectral types and luminosity classes. The spectra were obtained with the Immersion GRating INfrared Spectrograph covering the full range of the H (1.496-1.780{mu}m) and K (2.080-2.460{mu}m) atmospheric windows. The targets were primarily selected for being MK standard stars covering a wide range of effective temperatures and surface gravities, with metallicities close to the solar value. Currently, the library includes flux-calibrated and telluric-absorption-corrected spectra of 84 stars, with prospects for expansion to provide denser coverage of the parametric space. Throughout the H and K atmospheric windows, we identified spectral lines that are sensitive to Teff or logg and defined corresponding spectral indices. We also provide their equivalent widths (EWs). For those indices, we derive empirical relations between the measured EWs and the stellar atmospheric parameters. Therefore, the derived empirical equations can be used to calculate the Teff and logg of a star without requiring stellar atmospheric models.
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- ID:
- ivo://CDS.VizieR/J/ApJ/767/95
- Title:
- Improved stellar parameters of smallest KIC stars
- Short Name:
- J/ApJ/767/95
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We use the optical and near-infrared photometry from the Kepler Input Catalog to provide improved estimates of the stellar characteristics of the smallest stars in the Kepler target list. We find 3897 dwarfs with temperatures below 4000K, including 64 planet candidate host stars orbited by 95 transiting planet candidates. We refit the transit events in the Kepler light curves for these planet candidates and combine the revised planet/star radius ratios with our improved stellar radii to revise the radii of the planet candidates orbiting the cool target stars. We then compare the number of observed planet candidates to the number of stars around which such planets could have been detected in order to estimate the planet occurrence rate around cool stars. We find that the occurrence rate of 0.5-4R_{oplus}_ planets with orbital periods shorter than 50 days is 0.90_0.03_^0.04^ planets per star. The occurrence rate of Earth-size (0.5-1.4R_{oplus}_) planets is constant across the temperature range of our sample at 0.51_0.05_^0.06^ Earth-size planets per star, but the occurrence of 1.4-4R_{oplus}_ planets decreases significantly at cooler temperatures. Our sample includes two Earth-size planet candidates in the habitable zone, allowing us to estimate that the mean number of Earth-size planets in the habitable zone is 0.15_0.06_^0.13^ planets per cool star. Our 95% confidence lower limit on the occurrence rate of Earth-size planets in the habitable zones of cool stars is 0.04 planets per star. With 95% confidence, the nearest transiting Earth-size planet in the habitable zone of a cool star is within 21pc. Moreover, the nearest non-transiting planet in the habitable zone is within 5pc with 95% confidence.
- ID:
- ivo://CDS.VizieR/J/A+A/523/A17
- Title:
- Individual stars in Fornax dSph center
- Short Name:
- J/A+A/523/A17
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- For the first time we show the detailed, late-stage, chemical evolution history of a small nearby dwarf spheroidal galaxy in the Local Group. We present the results of a high-resolution (R~20000, {lambda}=5340-5620; 6120-6701) FLAMES/GIRAFFE abundance study at ESO/VLT of 81 photometrically selected, red giant branch stars in the central 25' of the Fornax dwarf spheroidal galaxy. We also carried out a detailed comparison of the effects of recent developments in abundance analysis (e.g., spherical models vs. plane-parallel) and the automation that is required to efficiently deal with such large data sets. We present abundances of alpha-elements (Mg, Si, Ca, and Ti), iron-peak elements (Fe, Ni, and Cr), and heavy elements (Y, Ba, La, Nd, and Eu).
- 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.
- ID:
- ivo://CDS.VizieR/J/ApJ/715/277
- Title:
- Insights into the Cepheid distance scale
- Short Name:
- J/ApJ/715/277
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a detailed investigation of the Cepheid distance scale by using both theory and observations. Through the use of pulsation models for fundamental mode Cepheids, we found that the slope of the period-luminosity (P-L) relation covering the entire period range (0.40<=logP<=2.0) becomes steeper when moving from optical to near-infrared (NIR) bands, and that the metallicity dependence of the slope decreases from the B- to the K band. The sign of the metallicity dependence for the slopes of the P-LV and P-LI relation is at odds with some recent empirical estimates. We determined new homogeneous estimates of V- and I-band slopes for 87 independent Cepheid data sets belonging to 48 external galaxies with nebular oxygen abundance 7.5<=12+log(O/H)<=8.9. We investigated the dependence of the period-Wesenheit (P-W) relations on the metal content and we found that the slopes of optical and NIR P-W relations in external galaxies are similar to the slopes of Large Magellanic Cloud (LMC) Cepheids. They also agree with the theoretical predictions suggesting that the slopes of the P-W relations are independent of the metal content.
- ID:
- ivo://CDS.VizieR/J/AJ/159/216
- Title:
- Ions density in the CGM of low mass galaxy groups
- Short Name:
- J/AJ/159/216
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We explore how environment affects the metallicity of the circumgalactic medium (CGM) using 13 low-mass galaxy groups (two to five galaxies) at <z_abs_>=0.25 identified near background quasars. Using quasar spectra from the Hubble Space Telescope/Cosmic Origins Spectrograph (HST/COS) and from Keck/High Resolution Echelle Spectrometer (Keck/HIRES) or the Very Large Telescope/Ultraviolet and Visual Echelle Spectrograph (VLT/UVES), we measure column densities of or determine limits on CGM absorption lines. We use a Markov Chain Monte Carlo approach with Cloudy to estimate metallicities of cool (T~104K) CGM gas within groups and compare them to CGM metallicities of 47 isolated galaxies. Both group and isolated CGM metallicities span a wide range (-2<[Si/H]<0), where the mean group (-0.54{pm}0.22) and isolated (-0.77{pm}0.14) CGM metallicities are similar. Group and isolated environments have similar distributions of HI column densities as a function of impact parameter. However, contrary to isolated galaxies, we do not find an anticorrelation between HI column density and the nearest group galaxy impact parameter. We additionally divided the groups by member luminosity ratios (i.e., galaxy-galaxy and galaxy-dwarf groups). While there was no significant difference in their mean metallicities, a modest increase in sample size should allow one to statistically identify a higher CGM metallicity in galaxy-dwarf groups compared to galaxy-galaxy groups. We conclude that either environmental effects have not played an important role in the metallicity of the CGM at this stage and expect that this may only occur when galaxies are strongly interacting or merging or that some isolated galaxies have higher CGM metallicities due to past interactions. Thus, environment does not seem to be the cause of the CGM metallicity bimodality.
- ID:
- ivo://CDS.VizieR/J/AJ/143/87
- Title:
- IRAC photometry of massive M31 globular clusters
- Short Name:
- J/AJ/143/87
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Several population synthesis models now predict integrated colors of simple stellar populations in the mid-infrared bands. To date, the models have not been extensively tested in this wavelength range. In a comparison of the predictions of several recent population synthesis models, the integrated colors are found to cover approximately the same range but to disagree in detail, for example, on the effects of metallicity. To test against observational data, globular clusters (GCs) are used as the closest objects to idealized groups of stars with a single age and single metallicity. Using recent mass estimates, we have compiled a sample of massive, old GCs in M31 which contain enough stars to guard against the stochastic effects of small-number statistics, and measured their integrated colors in the Spitzer/IRAC bands. Comparison of the cluster photometry in the IRAC bands with the model predictions shows that the models reproduce the cluster colors reasonably well, except for a small (not statistically significant) offset in [4.5]-[5.8]. In this color, models without circumstellar dust emission predict bluer values than are observed. Model predictions of colors formed from the V band and the IRAC 3.6 and 4.5{micro}m bands are redder than the observed data at high metallicities and we discuss several possible explanations. In agreement with model predictions, V-[3.6] and V-[4.5] colors are found to have metallicity sensitivity similar to or slightly better than V-K_s_.
- ID:
- ivo://CDS.VizieR/J/A+A/632/A19
- Title:
- IRAM intensity maps of 3 low-mass protostars
- Short Name:
- J/A+A/632/A19
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Methanol is a key species in astrochemistry since it is the most abundant organic molecule in the interstellar medium and is thought to be the mother molecule of many complex organic species. Estimating the deuteration of methanol around young protostars is of crucial importance because it highly depends on its formation mechanisms and the physical conditions during its moment of formation. We analyse several dozens of transitions from deuterated methanol isotopologues coming from various existing observational datasets obtained with the IRAM-PdBI and ALMA sub-mm interferometers to estimate the methanol deuteration surrounding three low-mass protostars on Solar System scales. A population diagram analysis allows us to derive a [CH_2_DOH]/[CH_3_OH] abundance ratio of 3-6% and a [CH_3_OD]/[CH_3_OH] ratio of 0.4-1.6% in the warm inner (<100-200AU) protostellar regions. These values are typically ten times lower than those derived with previous single-dish observations towards these sources but they are one to two orders of magnitude higher than the methanol deuteration measured in massive hot cores. Dust temperature maps obtained from Herschel and Planck observations show that massive hot cores are located in warmer molecular clouds than low-mass sources, with temperature differences of about 10K. The comparison of our measured values with the predictions of the gas-grain astrochemical model GRAINOBLE shows that such a temperature difference is sufficient to explain the different deuteration observed in low- to high-mass sources. This suggests that the physical conditions of the molecular cloud at the origin of the protostars mostly govern the present observed deuteration of methanol and, therefore, of more complex organic molecules. Finally, the methanol deuteration measured towards young solar-type protostars on Solar System scales seems to be higher by a factor of about 5 than the upper limit in methanol deuteration estimated in comet Hale-Bopp. If this result is confirmed by subsequent observations of other comets, this would imply that an important reprocessing of the organic material likely occurred in the solar nebula during the formation of the Solar System.
- ID:
- ivo://CDS.VizieR/J/ApJ/826/171
- Title:
- IR data of debris disk vs metallicity of stars
- Short Name:
- J/ApJ/826/171
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We find that the initial dust masses in planetary debris disks are correlated with the metallicities of their central stars. We compiled a large sample of systems, including Spitzer, the Herschel DUNES and DEBRIS surveys, and WISE debris disk candidates. We also merged 33 metallicity catalogs to provide homogeneous [Fe/H] and {sigma}_[Fe/H]_ values. We analyzed this merged sample, including 222 detected disks (74 warm and 148 cold) around a total of 187 systems (some with multiple components) and 440 disks with only upper limits (125 warm and 315 cold) around a total of 360 systems. The disk dust masses at a common early evolutionary point in time were determined using our numerical disk evolutionary code, evolving a unique model for each of the 662 disks backward to an age of 1Myr. We find that disk-bearing stars seldom have metallicities less than [Fe/H]=-0.2 and that the distribution of warm component masses lacks examples with large mass around stars of low metallicity ([Fe/H]<-0.085). Previous efforts to find a correlation have been largely unsuccessful; the primary improvements supporting our result are (1) basing the study on dust masses, not just infrared excess detections; (2) including upper limits on dust mass in a quantitative way; (3) accounting for the evolution of debris disk excesses as systems age; (4) accounting fully for the range of uncertainties in metallicity measurements; and (5) having a statistically large enough sample.
- ID:
- ivo://CDS.VizieR/J/A+A/529/A161
- Title:
- IRDC core G11.11-0.12P1 methanol maps
- Short Name:
- J/A+A/529/A161
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a study with the Plateau de Bure Interferometer of a core in the archetypal filamentary IRDC G11.11-0.12 of a few arcsecond resolution to determine its physical and chemical structures. The data consist of continuum and line observations covering the C^34^S 2-1 line and the methanol 2_k_-1_k_ v_t_=0 lines at 3mm and the methanol 5_k_-4_k_ v_t_=0 lines at1mm. Our observations show extended emission in the continuum at 1 and 3mm. The methanol 2-1 emission has three maxima extending over a 1pc scale (when merged with single-dish short-spacing observations); one of the maxima is spatially coincident with the continuum emission. The fitting results show an enhanced methanol fractional abundance at the central peak with respect to the other two peaks, where it decreases by about an order of magnitude. Wings in the CH_3_OH 2-1 spectra, and CH_3_OH abundance enhancements point to the presence of an outflow in the east-west direction. In addition, we find a gradient of ~4km/s in the same direction, which we interpret as being produced by an outflow(s)-cloud interaction.
