- ID:
- ivo://CDS.VizieR/III/197
- Title:
- IRAS Low Resolution Spectra
- Short Name:
- III/197
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The IRAS survey instrumentation included a low-resolution spectrometer which covered the wavelength range between 8 and 22 um. The spectrometer operated during the entire survey, providing spectra of the brighter point sources. For details about the spectrometer, the reader is referred to the published book, chapter IX. The spectra included in file "lrs.dat" contain 200 points each, 100 points in the 8-13um range, and 100 points in the 11-22um range. There is therefore an overlapping between the longer wavelengths of the first sample and the shorter wavelengths of the second sample. The data points are stored as scaled integer arrays in the file "lrs.dat"; the corresponding values of the wavelengths are available in the file "calib.dat" . The file "lrs.dat" includes also data taken from the IRAS point source catalog <II/125>.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/633/A7
- Title:
- IRAS 16293-2422 spectral cubes
- Short Name:
- J/A+A/633/A7
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Temperature is a crucial parameter in circumstellar disk evolution and planet formation because it governs the resistance of the gas to gravitational instability and sets the chemical composition of the planet-forming material. We set out to determine the gas temperature of the young disk-like structure around the Class 0 protostar IRAS 16293-2422A. We used Atacama Large Millimeter/submillimeter Array (ALMA) observations of multiple H_2_CS J=7-6 and J=10-9 lines from the Protostellar Interferometric Line Survey (PILS) to create a temperature map for the inner ~200AU of the disk-like structure. This molecule is a particularly useful temperature probe because transitions between energy levels with different K_a quantum numbers operate only through collisions. Based on the H_2_CS line ratios, the temperature is between ~100-175K in the inner ~150AU, and drops to ~75K at ~200AU. At the current resolution (0.5"~70AU), no jump is seen in the temperature at the disk-envelope interface. The temperature structure derived from H_2_CS is consistent with envelope temperature profiles that constrain the temperature from 1000AU scales down to ~100AU, but does not follow the temperature rise seen in these profiles at smaller radii. Higher angular resolution observations of optically thin temperature tracers are needed to establish whether cooling by gas-phase water, the presence of a putative disk, or the dust optical depth influences the gas temperature at <~100AU scales. The temperature at 100AU is higher in IRAS 16293A than in the embedded Class 0/I disk L1527, consistent with the higher luminosity of the former.
- ID:
- ivo://CDS.VizieR/J/A+A/649/A84
- Title:
- IR band features around HD100546
- Short Name:
- J/A+A/649/A84
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- Carbonaceous nanograins are present at the surface of protoplanetary disks around Herbig Ae/Be stars, where most of the ultraviolet energy from the central star is dissipated. Efficiently coupled to the gas, they are unavoidable to understand the physics and chemistry of these disks. Furthermore, nanograins are able to trace the outer flaring parts of the disk and possibly the gaps from which the larger grains are missing. However, their evolution through the disks, from internal to external regions, is only poorly understood so far. Our aim is to examine the spatial distribution and evolution of the nanodust emission in the emblematic (pre-)transitional protoplanetary disk HD 100546. This disk shows many structures (annular gaps, rings, and spirals) and reveals very rich carbon nanodust spectroscopic signatures (aromatic, aliphatic) in a wide spatial range of the disk (~20-200au). We analysed adaptive optics spectroscopic observations in the 3-4um range (angular resolution of ~0.1") and imaging and spectroscopic observations in the 8-12um range (angular resolution of ~0.3"). The hyperspectral cube was decomposed into a sum of spatially coherent dust components using a Gaussian decomposition algorithm. We compared the data to model predictions using the heterogeneous dust evolution model for interstellar solids (THEMIS), which is integrated in the radiative transfer code POLARIS by calculating the thermal and stochastic heating of micro- and nanometre-sized dust grains for a given disk structure. We find that the aromatic features at 3.3, 8.6, and 11.3um, and the aliphatic features between 3.4 and 3.5um are spatially extended; each band shows a specific morphology dependent on the local physical conditions. The aliphatic-to-aromatic band ratio, 3.4/3.3, increases with the distance from the star from ~0.2 (at 0.2" or 20au) to ~0.45 (at 1" or 100au), suggesting UV processing. In the 8-12um observed spectra, several features characteristic of aromatic particles and crystalline silicates are detected. Their relative contribution changes with the distance to the star. The model predicts that the features and adjacent continuum are due to different combinations of grain sub-populations, in most cases with a high dependence on the intensity of the UV field. The model reproduces the spatial emission profiles of the bands well, except for the inner 20-40au, where the observed emission of the 3.3 and 3.4um bands is, unlike the predictions, flat and no longer increases with the UV field. With our approach that combines observational data in the near- to mid-IR and disk modelling, we deliver constraints on the spatial distribution of nano-dust particles as a function of the disk structure and radiation field.
- ID:
- ivo://CDS.VizieR/J/ApJ/834/185
- Title:
- IR-bright MSX sources in the SMC with Spitzer/IRS
- Short Name:
- J/ApJ/834/185
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have used the Infrared Spectrograph (IRS) on the Spitzer Space Telescope to observe stars in the Small Magellanic Cloud (SMC) selected from the Point Source Catalog of the Midcourse Space Experiment (MSX). We concentrate on the dust properties of the oxygen-rich evolved stars. The dust composition has smaller contributions from alumina compared to the Galaxy. This difference may arise from the lower metallicity in the SMC, but it could be a selection effect, as the SMC sample includes more stars that are brighter and thus more massive. The distribution of the SMC stars along the silicate sequence looks more like the Galactic sample of red supergiants than asymptotic giant branch stars (AGBs). While many of the SMC stars are definitively on the AGB, several also show evidence of hot bottom burning. Three of the supergiants show PAH emission at 11.3{mu}m. Two other sources show mixed chemistry, with both carbon-rich and oxygen-rich spectral features. One, MSX SMC 134, may be the first confirmed silicate/carbon star in the SMC. The other, MSX SMC 049, is a candidate post-AGB star. MSX SMC 145, previously considered a candidate OH/IR star, is actually an AGB star with a background galaxy at z=0.16 along the same line of sight. We consider the overall characteristics of all the MSX sources, the most infrared-bright objects in the SMC, in light of the higher sensitivity and resolution of Spitzer, and compare them with the object types expected from the original selection criteria. This population represents what will be seen in more distant galaxies by the upcoming James Webb Space Telescope (JWST). Color-color diagrams generated from the IRS spectra and the mid-infrared filters on JWST show how one can separate evolved stars from young stellar objects (YSOs) and distinguish among different classes of YSOs.
- ID:
- ivo://CDS.VizieR/J/A+A/574/A56
- Title:
- IRC +10216 17.8GHz-26.3GHz spectrum
- Short Name:
- J/A+A/574/A56
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- IRC +10216 is the prototypical carbon star exhibiting an extended molecular circumstellar envelope. Its spectral properties are therefore the template for an entire class of objects. The main goal is to systematically study the 1.3cm spectral line characteristics of IRC +10216. We carried out a spectral line survey with the Effelsberg-100m telescope toward IRC +10216. It covers the frequency range between 17.8GHz and 26.3GHz (K-band). In the circumstellar shell of IRC +10216, we find 78 spectral lines, among which 12 remain unidentified. The identified lines are assigned to 18 different molecules and radicals. A total of 23 lines from species known to exist in this envelope are detected for the first time outside the Solar System and there are additional 20 lines firstly detected in IRC +10216. The potential orgin of U lines is also discussed. Assuming local thermodynamic equilibrium (LTE), we determine rotational temperatures and column densities of 17 detected molecules. Molecular abundances relative to H_2_ are also estimated. A non-LTE analysis of NH_3_ shows that the bulk of its emission arises from the inner envelope with a kinetic temperature of 70+/-20K. Evidence for NH_3_ emitting gas with higher kinetic temperature is also obtained, and potential abundance differences between various ^13^C-bearing isotopologues of HC_5_N are evaluated. Overall, the isotopic ^12^C/^13^C ratio is estimated to be 49+/-9. Finally, a comparison of detected molecules in the 1.3cm range with the dark cloud TMC-1 indicates that silicate bearing molecules are more predominant in IRC +10216.
- ID:
- ivo://CDS.VizieR/J/A+A/606/A74
- Title:
- IRC +10216 13.3GHz-18.5GHz spectrum
- Short Name:
- J/A+A/606/A74
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A spectral line survey of IRC +10216 between 13.3 and 18.5GHz was carried out using the Shanghai Tian Ma 65 m Radio Telescope (TMRT-65m) with a sensitivity of <7mK. Thirty-five spectral lines of 12 different molecules and radicals were detected in total. Except for SiS, the detected molecules are all carbon-chain molecules, including HC_3_N, HC_5_N, HC_7_N, HC_9_N, C_6_H, C_6_H^-^, C_8_H, SiC_2_, SiC_4_, c-C_3_H_2_, and l-C_5_H. The presence of rich carbon-bearing molecules is consistent with the identity of IRC +10216 as a carbon-rich asymptotic giant branch (AGB) star. The excitation temperatures and column densities of the observed species are derived by assuming a local thermodynamic equilibrium and homogeneous conditions.
- ID:
- ivo://CDS.VizieR/J/A+A/639/A61
- Title:
- IR continuum, [CII] and [OI] maps of M33
- Short Name:
- J/A+A/639/A61
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- M33 is a gas rich spiral galaxy of the Local Group. Its vicinity allows us to study its interstellar medium (ISM) on linear scales corresponding to the sizes of individual giant molecular clouds. We investigate the relationship between the two major gas cooling lines and the total infrared (TIR) dust continuum. We mapped the emission of gas and dust in M33 using the far-infrared lines of [CII] and [OI](63um) and the total infrared continuum. The line maps were observed with the PACS spectrometer on board the Herschel Space Observatory. These maps have 50pc resolution and form a ~370pc wide stripe along its major axis covering the sites of bright HII regions, but also more quiescent arm and inter-arm regions from the southern arm at 2kpc galacto-centric distance to the south out to 5.7kpc distance to the north. Full-galaxy maps of the continuum emission at 24um from Spitzer/MIPS, and at 70um, 100um, and 160um from Herschel/PACS were combined to obtain a map of the TIR. TIR and [CII] intensities are correlated over more than two orders of magnitude. The range of TIR translates to a range of far ultraviolet (FUV) emission of G_0,obs_~2 to 200 in units of the average Galactic radiation field. The binned [CII]/TIR ratio drops with rising TIR, with large, but decreasing scatter. The contribution of the cold neutral medium to the [CII] emission, as estimated from VLA HI data, is on average only 10%. Fits of modified black bodies (MBBs) to the continuum emission were used to estimate dust mass surface densities and total gas column densities. A correction for possible foreground absorption by cold gas was applied to the [OI] data before comparing it with models of photon dominated regions (PDRs). Most of the ratios of [CII]/[OI] and ([CII]+[OI])/TIR are consistent with two model solutions. The median ratios are consistent with one solution at n~2x10^2^cm^-3^, G_0_~60, and and a second low-FUV solution at n~10^4^cm^-3^, G_0_~1.5. The bulk of the gas along the lines-of-sight is represented by a low-density, high-FUV phase with low beam filling factors ~1. A fraction of the gas may, however, be represented by the second solution.
- ID:
- ivo://CDS.VizieR/J/A+A/603/A22
- Title:
- IRDCs cores spectra of HCN and HNC isotopologue
- Short Name:
- J/A+A/603/A22
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of the measurement of nitrogen fractionation in a sample of infrared-dark clouds (IRDCs) cores which are believed to be the precursors of high-mass stars and star clusters. We observed the J=1-0 transitions of HCN, H^13/^CN, HC^15/^N, HN^13/^C, and H^15/^NC towards a sample of 22 cores in four IRDCs using the IRAM 30m telescope.Assuming LTE and a temperature of 15K, the 14N/^15/^N ratios measured are consistent with the terrestrial atmosphere(TA) and protosolar nebula(PSN) values, and with the ratios measured in low-mass prestellar cores. However, the 14N/^15/^N ratios measured in cores C1, C3, F1, F2, and G2 do not agree with the results from similar studies towards the same cores using nitrogen bearing molecules with nitrile functional group(-CN) and nitrogen hydrides (-NH) although the ratio spread covers a similar range. Relatively low 14N/^15/^N ratios amongst the four-IRDCs were measured in IRDC G which are comparable to those measured in small cosmomaterials and protoplanetary disks. The low average gas density of this cloud suggests that the gas density, rather than the gas temperature, may be the dominant parameter influencing the initial nitrogen isotopic composition in young PSN.
- ID:
- ivo://CDS.VizieR/J/AJ/144/11
- Title:
- IR imaging, nuclear SEDs, Spitzer spectra of 22 AGNs
- Short Name:
- J/AJ/144/11
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present high-resolution mid-infrared (MIR) imaging, nuclear spectral energy distributions (SEDs), and archival Spitzer spectra for 22 low-luminosity active galactic nuclei (LLAGNs; L_bol_<~10^42^erg/s). Infrared (IR) observations may advance our understanding of the accretion flows in LLAGNs, the fate of the obscuring torus at low accretion rates, and, perhaps, the star formation histories of these objects. However, while comprehensively studied in higher-luminosity Seyferts and quasars, the nuclear IR properties of LLAGNs have not yet been well determined. We separate the present LLAGN sample into three categories depending on their Eddington ratio and radio emission, finding different IR characteristics for each class. (1) At the low-luminosity, low-Eddington-ratio (log L_bol_/L_Edd_< -4.6) end of the sample, we identify "host-dominated" galaxies with strong polycyclic aromatic hydrocarbon bands that may indicate active (circum-)nuclear star formation. (2) Some very radio-loud objects are also present at these low Eddington ratios. The IR emission in these nuclei is dominated by synchrotron radiation, and some are likely to be unobscured type 2 AGNs that genuinely lack a broad-line region. (3) At higher Eddington ratios, strong, compact nuclear sources are visible in the MIR images. The nuclear SEDs of these galaxies are diverse; some resemble typical Seyfert nuclei, while others lack a well-defined MIR "dust bump." Strong silicate emission is present in many of these objects. We speculate that this, together with high ratios of silicate strength to hydrogen column density, could suggest optically thin dust and low dust-to-gas ratios, in accordance with model predictions that LLAGNs do not host a Seyfert-like obscuring torus. We anticipate that detailed modeling of the new data and SEDs in terms of accretion disk, jet, radiatively inefficient accretion flow, and torus components will provide further insights into the nuclear structures and processes of LLAGNs.
- ID:
- ivo://CDS.VizieR/J/ApJ/723/895
- Title:
- IR luminosities and aromatic features of 5MUSES
- Short Name:
- J/ApJ/723/895
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We study a 24um selected sample of 330 galaxies observed with the infrared spectrograph for the 5mJy Unbiased Spitzer Extragalactic Survey (5MUSES). We estimate accurate total infrared luminosities by combining mid-IR spectroscopy and mid-to-far infrared photometry, and by utilizing new empirical spectral templates from Spitzer data. The infrared luminosities of this sample range mostly from 10^9^L_{sun}_ to 10^13.5^L_{sun}_, with 83% in the range 10^10^L_{sun}_<L_IR_<10^12^L_{sun}_. The redshifts range from 0.008 to 4.27, with a median of 0.144. The equivalent widths of the 6.2um aromatic feature have a bimodal distribution, probably related to selection effects. We use the 6.2um polycyclic aromatic hydrocarbon equivalent width (PAH EW) to classify our objects as starburst (SB)-dominated (44%), SB-AGN composite (22%), and active galactic nucleus (AGN)-dominated (34%). The high EW objects (SB-dominated) tend to have steeper mid-IR to far-IR spectral slopes and lower LIR and redshifts.
