- 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.
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Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/394/1875
- Title:
- IR colours of MASH planetary nebulae
- Short Name:
- J/MNRAS/394/1875
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have analysed the near-infrared (NIR) and far-infrared (FIR) colours of MASH I and MASH II (the Macquarie/AAO/Strasbourg surveys, Cat. <V/127>) planetary nebulae (PNe), using data deriving from the Two-Micron All-Sky Survey and Infrared Astronomical Satellite. We were able to identify ~5 per cent of the sources in the NIR, and a slightly larger fraction (~12 per cent) in the FIR. It is concluded that whilst the NIR colours of these nebulae are consistent with those of less evolved (and higher surface brightness) PNe, their FIR colours are markedly different. This disparity is likely to arise as a result of an evolution in dust temperatures, in their line emission characteristics, and in the relative contributions of the 8.6 and 11.3um polycyclic aromatic hydrocarbon emission features. A rump of~9 per cent of the detected sources have values log[F(25um)/F(60um)] which are lower than can be explained in terms of normal nebular evolution, however. If these are comparable in nature to the undetected PNe, then this would argue that ~1 in 10 of MASH I and II nebulae may represent galactic H ii regions, Stromgren spheres, symbiotic nebulae or other unrelated categories of source.
- 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/ApJ/563/L49
- Title:
- IR counterpart of the X-ray pulsar 1E 2259+586
- Short Name:
- J/ApJ/563/L49
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present near-infrared and optical observations of the field of the anomalous X-ray pulsar 1E 2259+586 taken with the Keck telescope. We derive a sub-arcsecond Chandra position and tie it to our optical reference frame using other stars in the field. We find a very faint source, K_S_=21.7+/-0.2mag, with a position coincident with the Chandra position. We argue that this is the counterpart. In the J, I, and R bands, we derive (2{sigma}) limits of 23.8, 25.6, and 26.4mag, respectively. As with 4U 0142+61, for which a counterpart has previously been found, our results are inconsistent with models in which the source is powered by accretion from a disk but may be consistent with the magnetar model.
- ID:
- ivo://CDS.VizieR/J/AJ/162/82
- Title:
- IRD and HPF spectra of TRAPPIST-1b,e and f
- Short Name:
- J/AJ/162/82
- Date:
- 11 Mar 2022
- Publisher:
- CDS
- Description:
- We obtained high-resolution spectra of the ultracool M-dwarf TRAPPIST-1 during the transit of its planet "b" using two high-dispersion near-infrared spectrographs, the Infrared Doppler (IRD) instrument on the Subaru 8.2m telescope, and the Habitable Zone Planet Finder (HPF) instrument on the 10m Hobby-Eberly Telescope. These spectroscopic observations are complemented by a photometric transit observation for planet "b" using the APO/ARCTIC, which assisted us in capturing the correct transit times for our transit spectroscopy. Using the data obtained by the new IRD and HPF observations, as well as the prior transit observations of planets "b," "e" and "f" from IRD, we attempt to constrain the atmospheric escape of the planet using the Hei triplet 10830{AA} absorption line. We do not detect evidence for any primordial extended H-He atmospheres in all three planets. To limit any planet-related absorption, we place an upper limit on the equivalent widths of <7.754m{AA} for planet "b," <10.458m{AA} for planet "e," <4.143m{AA} for planet "f" at 95% confidence from the IRD data, and <3.467m{AA} for planet "b" at 95% confidence from HPF data. Using these limits along with a solar- like composition isothermal Parker wind model, we attempt to constrain the mass-loss rates for the three planets. For TRAPPIST-1b, our models exclude the highest possible energy-limited rate for a wind temperature <5000K. This nondetection of extended atmospheres with low mean-molecular weights in all three planets aids in further constraining their atmospheric composition by steering the focus toward the search of high-molecular-weight species in their atmospheres.
- 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/559/A79
- Title:
- IRDC APEX/SABOCA observations
- Short Name:
- J/A+A/559/A79
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Infrared-dark clouds (IRDCs) harbor the early phases of cluster and high-mass star formation and are comprised of cold (~20K), dense (n>10^4^cm^-3^) gas. The spectral energy distribution (SED) of IRDCs is dominated by the far-infrared and millimeter wavelength regime, and our initial Herschel study examined IRDCs at the peak of the SED with high angular resolution. Here we present a follow-up study using the SABOCA instrument on APEX which delivers 7.8" angular resolution at 350{mu}m, matching the resolution we achieved with Herschel/PACS, and allowing us to characterize substructure on ~0.1pc scales. Our sample of 11 nearby IRDCs are a mix of filamentary and clumpy morphologies, and the filamentary clouds show significant hierarchical structure, while the clumpy IRDCs exhibit little hierarchical structure. All IRDCs, regardless of morphology, have about 14% of their total mass in small scale core-like structures which roughly follow a trend of constant volume density over all size scales. Out of the 89 protostellar cores we identified in this sample with Herschel, we recover 40 of the brightest and re-fit their SEDs and find their properties agree fairly well with our previous estimates (<T>~19K). We detect a new population of "cold cores" which have no 70{mu}m counterpart, but are 100 and 160{mu}m-bright, with colder temperatures (<T>~16K). This latter population, along with SABOCA-only detections, are predominantly low-mass objects, but their evolutionary diagnostics are consistent with the earliest starless or prestellar phase of cores in IRDCs.
- ID:
- ivo://CDS.VizieR/J/MNRAS/399/1506
- Title:
- IRDC cores in SCUBA Legacy Catalogue
- Short Name:
- J/MNRAS/399/1506
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an investigation of candidate infrared dark cloud (IRDC) cores as identified by Simon et al. (2006, Cat. J/ApJ/639/227) located within the Submillimetre Common User Bolometer Array (SCUBA) Legacy Catalogue. After applying a uniform noise cut to the catalogue data, we identify 154 IRDC cores that were detected at 850um and 51 cores that were not. We derive column densities for each core from their 8um extinction and find that the IRDCs detected at 850um have higher column densities (a mean of 1.7x10^22^cm^-2^) compared to those cores not detected at 850um (a mean of 1.0x10^22^cm-2).
- ID:
- ivo://CDS.VizieR/J/A+A/606/A133
- Title:
- IRDC G035.39-00.33 NH3 and CCS data cubes
- Short Name:
- J/A+A/606/A133
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Infrared dark clouds represent the earliest stages of high-mass star formation. Detailed observations of their physical conditions on all physical scales are required to improve our understanding of their role in fueling star formation. We investigate the large-scale structure of the IRDC G035.39-00.33, probing the dense gas with the classical ammonia thermometer. This allows us to put reliable constraints on the temperature of the extended, pc-scale dense gas reservoir and to probe the magnitude of its non-thermal motions. Available far-infrared observations can be used in tandem with the observed ammonia emission to estimate the total gas mass contained in G035.39-00.33. We identify a main velocity component as a prominent filament, manifested as an ammonia emission intensity ridge spanning more than 6 pc, consistent with the previous studies on the Northern part of the cloud. A number of additional line-of-sight components are found, and a large-scale linear velocity gradient of ~0.2km/s/pc is found along the ridge of the IRDC. In contrast to the dust temperature map, an ammonia-derived kinetic temperature map, presented for the entirety of the cloud, reveals local temperature enhancements towards the massive protostellar cores. We show that without properly accounting for the line of sight contamination, the dust temperature is 2-3K larger than the gas temperature measured with NH_3_. While both the large-scale kinematics and temperature structure are consistent with that of starless dark filaments, the kinetic gas temperature profile on smaller scales is suggestive of tracing the heating mechanism coincident with the locations of massive protostellar cores.
- ID:
- ivo://CDS.VizieR/J/ApJ/694/546
- Title:
- IR dust bubbles. II. YSOs model parameters
- Short Name:
- J/ApJ/694/546
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an analysis of late-O/early-B-powered, parsec-sized bubbles and associated star formation using Two Micron All Sky Survey, GLIMPSE, MIPSGAL, and MAGPIS surveys. Three bubbles were selected from the Churchwell et al. catalog (2007, Cat. J/ApJ/670/428). We confirm that the structure identified in Watson et al. (2008ApJ...681.1341W) holds in less energetic bubbles, i.e., a photodissociated region, identified by 8um emission due to polycyclic aromatic hydrocarbons surrounding hot dust, identified by 24um emission and ionized gas, and identified by 20cm continuum. We estimate the dynamical age of two bubbles by comparing bubble sizes to numerical models of Hosokawa and Inutsuka. We also identify and analyze candidate young stellar objects using spectral energy distribution (SED) fitting and identify sites of possible triggered star formation. Lastly, we identify likely ionizing sources for two sources based on SED fitting.
