- ID:
- ivo://CDS.VizieR/J/ApJ/825/96
- Title:
- IR spectrum of protonated ovalene (7-C_32_H_15_^+^)
- Short Name:
- J/ApJ/825/96
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The mid-infrared emission from galactic objects, including reflection nebulae, planetary nebulae, proto-planetary nebulae, molecular clouds, etc, as well as external galaxies, is dominated by the unidentified infrared (UIR) emission bands. Large protonated polycyclic aromatic hydrocarbons (H^+^PAHs) were proposed as possible carriers, but no spectrum of an H^+^PAH has been shown to exactly match the UIR bands. Here, we report the IR spectrum of protonated ovalene (7-C_32_H_15_^+^) measured in a para-hydrogen (p-H_2_) matrix at 3.2K, generated by bombarding a mixture of ovalene and p-H_2_ with electrons during matrix deposition. Spectral assignments were made based on the expected chemistry and on the spectra simulated with the wavenumbers and infrared intensities predicted with the B3PW91/6-311++G(2d,2p) method. The close resemblance of the observed spectral pattern to that of the UIR bands suggests that protonated ovalene may contribute to the UIR emission, particularly from objects that emit Class A spectra, such as the IRIS reflection nebula, NGC 7023.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/670/1115
- Title:
- IRS spectra at 38 positions in Galactic center
- Short Name:
- J/ApJ/670/1115
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present Spitzer IRS spectra (R~600, 10-38um) of 38 positions in the Galactic center, all at the same Galactic longitude and spanning +/-0.3{deg} in latitude. Our positions include the Arches Cluster, the Arched Filaments, regions near the Quintuplet Cluster, the "Bubble" lying along the same line of sight as the molecular cloud G0.11-0.11, and the diffuse interstellar gas along the line of sight at higher Galactic latitudes.
- ID:
- ivo://CDS.VizieR/J/ApJ/683/114
- Title:
- IRS spectra of faint IRAS sources
- Short Name:
- J/ApJ/683/114
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Extragalactic sources from the IRAS Faint Source Catalog (FSC) that have the optically faintest magnitudes (E>~18) were selected by spatial coincidence with a source in the FIRST radio survey, and 28 of these sources have been observed with the Infrared Spectrograph on Spitzer (IRS). While an infrared source is always detected with the IRS at the FIRST position, only ~50% of the infrared sources are real FSC detections, as estimated from the number of sources for which the f_v_(25um) determined with the IRS is fainter than the sensitivity limit for the FSC. Sources have 0.12<z<1.0 and luminosities 43.3<log[{nu}L_{nu}_(5.5um)]<46.7erg/s, encompassing the range from local ULIRGs to the most luminous sources discovered by Spitzer at z~2. Detectable PAH features are found in 15 of the sources (54%), and measurable silicate absorption is found in 19 sources (68%); both PAH emission and silicate absorption are present in 11 sources. PAH luminosities are used to determine the starburst fraction of bolometric luminosity, and model predictions for a dusty torus are used to determine the AGN fraction of luminosity in all sources based on vL_v_(5.5um). Approximately half of the sources have luminosity dominated by an AGN and approximately half by a starburst.
- ID:
- ivo://CDS.VizieR/J/A+A/620/A32
- Title:
- IRS spectra of 22 O7-B5 I-V stars
- Short Name:
- J/A+A/620/A32
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results of the analysis of a sample of 22 stars of spectral types from O7 to B5 and luminosity classes I-V for which spectra from the Infrared Spectrograph (IRS) of Spitzer are available. The IRS spectra of these stars are examined for signs of excess infrared (IR) emission by comparison with stellar atmospheric spectra. We find that the spectra of half of the studied stars are dominated by excess emission in the far-IR, including all six super- and bright giants. In order to examine the origin of the far-IR excess, we supplement the Spitzer data with optical high-resolution echelle spectroscopy ({lambda}{Delta}{lambda}~10^5^), near-IR high-contrast coronagraphic imaging taken with the SPHERE instrument at VLT with a spatial resolution of 0.05", and WISE and Herschel photometry. In the optical region, we detect various absorption and emission lines (H{alpha}, CIII, and NIII) irrespective of the far-IR excess. Pfund{alpha} and Humphrey{alpha} lines are observed at the same time as the far-IR excess. These lines are stronger in stars with far-IR excess than in stars without excess. A scattered-light disk in the central r<2.5" region of the far-IR excess stars HD149404, HD151804, and HD154368 can be excluded from H band imaging down to a 1{sigma} contrast of F(r)/F*~10^-6^. The far-IR excess is fit either by a free-free component from ionized gas as for the winds of hot stars or a large (1pc) circumstellar dust shell. The putative dust envelopes required to explain the excess have a visual extinction as low as a few hundred micro-mag.
- ID:
- ivo://CDS.VizieR/J/ApJ/705/89
- Title:
- IRS spectra of solar-type stars
- Short Name:
- J/ApJ/705/89
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have observed 152 nearby solar-type stars with the Infrared Spectrometer (IRS) on the Spitzer Space Telescope. Including stars that met our criteria but were observed in other surveys, we get an overall success rate for finding excesses in the long-wavelength IRS band (30-34um) of 11.8%+/-2.4%. The success rate for excesses in the short-wavelength band (8.5-12um) is ~1% including sources from other surveys. Two stars (HD 40136 and HD 10647) show weak evidence for spectral features; the excess emission in the other systems is featureless. For most stars with excesses, we detect an excess at both IRS and Multiband Imaging Photometer for Spitzer (MIPS) wavelengths. Only three stars in this sample show a MIPS 70um excess with no IRS excess, implying that very cold dust is rare around solar-type stars.
- ID:
- ivo://CDS.VizieR/J/AJ/151/146
- Title:
- IRS spectra with features of crystalline silicates
- Short Name:
- J/AJ/151/146
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The crystalline silicate features are mainly reflected in infrared bands. The Spitzer Infrared Spectrograph (IRS) collected numerous spectra of various objects and provided a big database to investigate crystalline silicates in a wide range of astronomical environments. We apply the manifold ranking algorithm to perform a systematic search for the spectra with crystalline silicate features in the Spitzer IRS Enhanced Products available. In total, 868 spectra of 790 sources are found to show the features of crystalline silicates. These objects are cross-matched with the SIMBAD database as well as with the Large Sky Area Multi-object Fiber Spectroscopic Telescope (LAMOST)/DR2 (Luo et al. 2016, Cat. V/149). The average spectrum of young stellar objects shows a variety of features dominated either by forsterite or enstatite or neither, while the average spectrum of evolved objects consistently present dominant features of forsterite in AGB, OH/IR, post-AGB, and planetary nebulae. They are identified optically as early-type stars, evolved stars, galaxies and so on. In addition, the strength of spectral features in typical silicate complexes is calculated. The results are available through CDS for the astronomical community to further study crystalline silicates.
- ID:
- ivo://CDS.VizieR/J/A+A/397/177
- Title:
- IR star clusters and stellar groups catalog
- Short Name:
- J/A+A/397/177
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We compiled a catalogue of infrared star clusters in the Galaxy, which are most of them embedded. It condenses the growing literature information. We also include in the sample infrared stellar groups which are less dense than star clusters, such as those embedded in the dark clouds Taurus-Auriga and Chamaleon I. We provide galactic and equatorial coordinates, angular dimensions, different designations and related objects such as nebulae. A total of 189 infrared clusters and 87 embedded stellar groups are included. A fraction of 25% of the embedded clusters are projected close to each other in pair or triplet systems, indicating that multiplicity plays an important role in star cluster formation.
- ID:
- ivo://CDS.VizieR/J/A+A/392/239
- Title:
- IR survey of outflows in Orion A
- Short Name:
- J/A+A/392/239
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have made an unbiased imaging survey of a 1.2 square degree area in the Orion A giant molecular cloud searching for molecular hydrogen emission line features seen in the v=1-0 S(1) line at a wavelength of 2.12{mu}m originating in shocks in outflows from young stellar objects. This survey provides for the first time an unbiased census of outflows over a significant portion of a giant molecular cloud, and yields a sample of outflows free from selection effects and with all objects located at roughly the same, well-known distance. In this paper, we present the data gathered in the course of the survey, provide a comprehensive list of all molecular hydrogen emission features found, and give a list of the 76 candidate outflows identified in the data set.
- ID:
- ivo://CDS.VizieR/J/ApJ/788/123
- Title:
- IRTF J-band spectrum of Mrk 231
- Short Name:
- J/ApJ/788/123
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first J-band spectrum of Mrk 231, which reveals a large He I* {lambda}10830 broad absorption line with a profile similar to that of the well-known Na I broad absorption line. Combining this spectrum with optical and UV spectra from the literature, we show that the unusual reddening noted by Veilleux et al. (2013ApJ...764...15V) is explained by a reddening curve like those previously used to explain low values of total-to-selective extinction in Type Ia supernovae. The nuclear starburst may be the origin and location of the dust. Spatially resolved emission in the broad absorption line trough suggests nearly full coverage of the continuum emission region. The broad absorption lines reveal higher velocities in the He I* lines (produced in the quasar-photoionized H II region) compared with the Na I and Ca II lines (produced in the corresponding partially ionized zone). Cloudy simulations show that a density increase is required between the H II and partially ionized zones to produce ionic column densities consistent with the optical and IR absorption line measurements and limits, and that the absorber lies ~100 pc from the central engine. These results suggest that the He I* lines are produced in an ordinary quasar BAL wind that impacts upon, compresses, and accelerates the nuclear starburst's dusty effluent (feedback in action), and the Ca II and Na I lines are produced in this dusty accelerated gas. This unusual circumstance explains the rarity of Na I absorption lines; without the compression along our line of sight, Mrk 231 would appear as an ordinary iron low-ionization, broad absorption line quasar.
- ID:
- ivo://CDS.VizieR/J/AJ/162/187
- Title:
- IRTF spectral indices for giant stars
- Short Name:
- J/AJ/162/187
- Date:
- 15 Mar 2022
- Publisher:
- CDS
- Description:
- We present infrared spectral indices (1.0-2.3{mu}m) of Galactic late-type giants and red supergiants (RSGs). We used existing and new spectra obtained at resolution power R=2000 with SpeX on the IRTF telescope. While a large CO equivalent width (EW), at 2.29{mu}m ([CO,2.29]>~45{AA}) is a typical signature of RSGs later than spectral type M0, [CO] of K-type RSGs and giants are similar. In the [CO,2.29] versus [MgI,1.71] diagram, RSGs of all spectral types can be distinguished from red giants because the MgI line weakens with increasing temperature and decreasing gravity. We find several lines that vary with luminosity, but not temperature: SiI (1.59{mu}m), Sr (1.033{mu}m), Fe+Cr+Si+CN (1.16{mu}m), Fe+Ti (1.185{mu}m), Fe+Ti (1.196{mu}m), Ti+Ca (1.28{mu}m), and Mn (1.29{mu}m). Good markers of CN enhancement are the Fe+Si+CN line at 1.087{mu}m and CN line at 1.093{mu}m. Using these lines, at the resolution of SpeX, it is possible to separate RSGs and giants. Contaminant O-rich Mira and S-type AGBs are recognized by strong molecular features due to water vapor features, TiO band heads, and/or ZrO absorption. Among the 42 candidate RSGs that we observed, all but one were found to be late types. Twenty-one have EWs consistent with those of RSGs, 16 with those of O-rich Mira AGBs, and one with an S-type AGB. These infrared results open new, unexplored, potential for searches at low resolution of RSGs in the highly obscured innermost regions of the Milky Way.
