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Start Over Subject interstellar medium
1. 3600-24700{AA} deep X-shooter spectrum of HH 1
ID:
ivo://CDS.VizieR/J/ApJ/814/52
Title:
3600-24700{AA} deep X-shooter spectrum of HH 1
Short Name:
J/ApJ/814/52
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present deep spectroscopic (3600-24700{AA}) X-shooter observations of the bright Herbig-Haro object HH 1, one of the best laboratories to study the chemical and physical modifications caused by protostellar shocks on the natal cloud. We observe atomic fine structure lines, HI and HeI recombination lines and H_2_ ro-vibrational lines (more than 500 detections in total). Line emission was analyzed by means of Non-local Thermal Equilibiurm codes to derive the electron temperature and density, and for the first time we are able to accurately probe different physical regimes behind a dissociative shock. We find a temperature stratification in the range 4000K/80000K, and a significant correlation between temperature and ionization energy. Two density regimes are identified for the ionized gas, a more tenuous, spatially broad component (density ~10^3^/cm^3^), and a more compact component (density>=10^5^/cm^3^) likely associated with the hottest gas. A further neutral component is also evidenced, having a temperature <~10000K and a density >10^4^/cm^3^. The gas fractional ionization was estimated by solving the ionization equilibrium equations of atoms detected in different ionization stages. We find that neutral and fully ionized regions co-exist inside the shock. Also, indications in favor of at least partially dissociative shock as the main mechanism for molecular excitation are derived. Chemical abundances are estimated for the majority of the detected species. On average, abundances of non-refractory/refractory elements are lower than solar of about 0.15/0.5dex. This indicates the presence of dust inside the medium, with a depletion factor of iron of ~40%.
2. 15273{AA} near-infrared DIB
ID:
ivo://CDS.VizieR/J/A+A/628/A67
Title:
15273{AA} near-infrared DIB
Short Name:
J/A+A/628/A67
Date:
21 Oct 2021
Publisher:
CDS
Description:
The latest SDSS/APOGEE data release DR14 has provided an increased number of stellar spectra in the H band and associated stellar models using an innovative algorithm known as The Cannon. We took advantage of these novelties to extract the 15273{AA} near-infrared DIB and to study its link with dust extinction and emission. We modified our automated fitting methods dedicated for hot stars and used in earlier studies with some adaptations motivated by the change from early- or intermediate-type stars to red giants. A new method has also been developed to quantify the upper limits on DIB strengths. Careful and thorough examinations of the DIB parameters, the continuum shape and the quality of the adjustment of the model to the data were done. We compared our DIB measurements with the stellar extinctions Av from the Starhorse database. We then compared the resulting DIB-extinction ratio with the dust optical depth derived from Planck data, globally and also separately for nearby off-Plane cloud complexes. Our analysis has led to the production of a catalog containing 124 064 new measurements of the 15273{AA} DIB, allowing us to revisit the correlation between DIB strength and dust reddening.
3. 3060-3700{AA} spectra analysis of early-type stars
ID:
ivo://CDS.VizieR/J/ApJS/216/22
Title:
3060-3700{AA} spectra analysis of early-type stars
Short Name:
J/ApJS/216/22
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a comprehensive and sensitive unbiased survey of interstellar features in the near-UV range (3050-3700{AA}). We combined a large number of VLT/UVES archival observations of a sample of highly reddened early-type stars -typical diffuse interstellar band targets- and unreddened standards. We stacked the individual observations to obtain a reddened "superspectrum" in the interstellar rest frame with a signal-to-noise ratio exceeding 1500. We compared this to the analogous geocentric and stellar rest frame superspectra as well as to an unreddened superspectrum to find interstellar absorption features. We find 30 known features (11 atomic and 19 molecular) and tentatively detect up to 7 new interstellar absorption lines of unknown origin. Our survey is sensitive to narrow and weak features; telluric residuals preclude us from detecting broader features. For each sightline, we measured fundamental parameters (radial velocities, line widths, and equivalent widths) of the detected interstellar features. We also revisit upper limits for the column densities of small, neutral polycyclic aromatic hydrocarbon molecules that have strong transitions in this wavelength range.
4. A catalog of outer ejecta knots in Cas A
ID:
ivo://CDS.VizieR/J/ApJS/179/195
Title:
A catalog of outer ejecta knots in Cas A
Short Name:
J/ApJS/179/195
Date:
21 Oct 2021
Publisher:
CDS
Description:
Hubble Space Telescope images of the core-collapse supernova remnant Cassiopeia A are used to identify high-velocity knots of ejecta located outside the remnant's main emission shell of expanding debris. These ejecta fragments are found near or ahead of the remnant's forward shock front and mostly lie from 120" to 300" in radial distance from the remnant's center of expansion. Filter flux ratios when correlated with published spectra show that these knots can be divided into three emission classes: (1) knots dominated by [NII] {lambda}6548,{lambda}6583 emissions, (2) knots dominated by [OII] {lambda}7319, {lambda}7330 emissions, and (3) knots displaying filter flux ratios suggestive of [SII], [OII], and [ArIII] {lambda}7135 emission line strengths similar to the "fast-moving knots" (FMKs) found in the remnant's bright main shell. Of 1825 knots identified, 444 are strong [NII] emission knots, 192 are strong [OII] emission knots, and 1189 are FMK-like knots. In terms of location around the remnant, 972, 207, and 646 knots are found in the remnant's northeast jet, southwest jet, and non-jet regions, respectively. Assuming a distance of 3.4kpc, derived knot transverse velocities based on proper motion measurements spanning a 9 month interval indicate maximum transverse expansion velocities for these three knot classes of 14500, 13500, and 11500km/s, respectively. We present a catalog of these outlying ejecta clumps comprising finding charts, epoch 2004.2 knot positions, proper motions, photometric filter fluxes, and estimated knot emission type, along with cross-references to previous knot identifications and data. This compilation represents a nearly tenfold increase in the number of outlying, high-velocity ejecta knots identified around the Cassiopeia A remnant.
5. A catalogue of high velocity molecular outflows
ID:
ivo://CDS.VizieR/J/A+AS/115/283
Title:
A catalogue of high velocity molecular outflows
Short Name:
J/A+AS/115/283
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a comprehensive catalogue of 264 high velocity molecular outflow sources that are compiled from publications and preprints as of May 1995, including position, bottom linewidth, maximum measurement of projected profile, polarity, collimation factor, outflow mass, luminosity and list of related references.
6. A compilation of interstellar column densities
ID:
ivo://CDS.VizieR/J/ApJS/199/8
Title:
A compilation of interstellar column densities
Short Name:
J/ApJS/199/8
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have collated absorption line data toward 3008 stars in order to create a unified database of interstellar column densities. These data have been taken from a number of different published sources and include many different species and ionizations. The preliminary results from our analysis show a tight relation [N(H)/E(B-V)=6.12x10^21^] between N(H) and E(B-V). Similar plots have been obtained with many different species, and their correlations along with the correlation coefficients are presented.
7. A 6.7GHz methanol maser survey. II. |b|<2{deg}
ID:
ivo://CDS.VizieR/J/ApJS/241/18
Title:
A 6.7GHz methanol maser survey. II. |b|<2{deg}
Short Name:
J/ApJS/241/18
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report the results of our systematic survey for Galactic 6.7GHz Class II CH_3_OH maser emission toward a sample of young stellar objects. The survey was conducted with the Shanghai Tianma Radio Telescope (TMRT). The sample consists of 3348 sources selected from the all-sky Wide-field Infrared Survey Explorer (WISE) point-source catalog. We discussed the selection criteria in detail and the detection results of those at high Galactic latitudes (i.e., |b|>2{deg}) in a previous paper (Paper I; Yang+ 2017, J/ApJ/846/160). Here, we present the results from the survey of those at low Galactic latitudes, i.e., |b|<2{deg}. Of 1875 selected WISE point sources, 291 positions that were actually associated with 224 sources that were detected with CH_3_OH maser emission. Among them, 32 are newly detected. A majority of the newly detected sources are associated with bright WISE sources. The majority of the detected sources (209/224=93.3%) are quite close to the Galactic Plane (|b|<1{deg}) and lie on the inner spiral arms with positive local standard of rest velocities. The detection rate and the color-color distribution of our detection are all matched with our anticipation. Combining with detections from previous surveys, we compile a catalog of 1085 sources with 6.7GHz CH_3_OH maser emission in our Galaxy.
8. A 95 GHz Survey of Methanol Masers
ID:
ivo://CDS.VizieR/J/AZh/72/22
Title:
A 95 GHz Survey of Methanol Masers
Short Name:
J/AZh/72/22
Date:
21 Oct 2021
Publisher:
CDS
Description:
A 95GHz survey of methanol emission in the 8_0_-7_1_A^+^ transition was conducted with the 20-m radio telescope at Onsala. Twenty-six new sources were detected in the emission line. At least nine out of the 35 studied sources are masers.
9. All-sky extinction maps
ID:
ivo://CDS.VizieR/J/A+A/585/A38
Title:
All-sky extinction maps
Short Name:
J/A+A/585/A38
Date:
21 Oct 2021
Publisher:
CDS
Description:
Extinction remains one of the most reliable methods of measuring column density of nearby Galactic interstellar clouds. The current and ongoing near-infrared surveys enable the mapping of extinction over large sky areas. We produce allsky extinction maps using the 2MASS near-infrared survey. We use the NICER and NICEST methods to convert the near-infrared colour excesses to extinction estimates. The results are presented in Healpix format at the resolutions of 3.0, 4.5, and 12.0-arcmin.
10. All-sky near-infrared extinction map
ID:
ivo://CDS.VizieR/J/A+A/585/A78
Title:
All-sky near-infrared extinction map
Short Name:
J/A+A/585/A78
Date:
21 Oct 2021
Publisher:
CDS
Description:
Near-infrared (NIR) extinction remains one of the most reliable methods of measuring the column density of dense interstellar clouds. Extinction can be estimated using the reddening of the light of background stars. Several methods exist (e.g., NICE, NICER, NICEST, GNICER) to combine observations of several NIR bands into extinction maps. We present a new method of estimating extinction based on NIR multiband observations and examine its performance. Our basic method uses a discretised version of the distribution of intrinsic stellar colours directly. The extinction of individual stars and the average over a resolution element are estimated with Markov chain Monte Carlo (MCMC) methods. Several variations of the basic method are tested, and the results are compared to NICER calculations.