- ID:
- ivo://CDS.VizieR/J/ApJ/643/965
- Title:
- Spitzer photometry of the Trifid nebula (M20)
- Short Name:
- J/ApJ/643/965
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Spitzer IRAC and MIPS images of the Trifid Nebula (M20) reveal its spectacular appearance in infrared light, highlighting the nebula's special evolutionary stage. The images feature recently formed massive protostars and numerous young stellar objects, and a single O star that illuminates the surrounding molecular cloud from which it formed, and unveil large-scale, filamentary dark clouds. Multiple protostars are detected in the infrared, within the cold dust cores of TC3 and TC4, which were previously defined as Class 0. The cold dust continuum cores of TC1 and TC2 contain only one protostar each. The Spitzer color-color diagram allowed us to identify 160 young stellar objects (YSOs) and classify them into different evolutionary stages. The diagram also revealed a unique group of YSOs that are bright at 24um but have the spectral energy distribution peaking at 58um.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/517/A44
- Title:
- Spitzer sources in the Galactic bulge
- Short Name:
- J/A+A/517/A44
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a photometric catalogue of seven selected fields towards the Galactic bulge, observed with the IRAC and MIPS imaging instruments on-board the Spitzer Space Telescope with unprecedented sensitivity. The locations of the fields are defined in Figure 1 and Table 1 of the paper. In each of the fields, tens of thousands of point sources were detected. The catalogue is split up into seven tables, according to the different fields. Table 5 in the paper gives ten lines of the band-merged catalogue of the Bulge N1 field as an example. In the first paper based on this data set, we present the observations, data reduction, the final catalogue of sources, and a detailed comparison to previous mid-IR surveys of the Galactic bulge, as well as to theoretical isochrones. We find in general good agreement with other surveys and the isochrones, supporting the high quality of our catalogue. Besides a catalogue for each field, fits files of the IRAC and MIPS mosaics are presented, too. As a cautionary note for the users, we would like to add that the least reliable sources in our catalogue are those with detection in only one IRAC band and no MIPS detection, and with (i) either no 2MASS and DENIS counterpart (depending on the field, between 3.1% and 6.7% of the sources), or (ii) a DENIS and 2MASS counterpart at a distance between 1.6 and 3 arcseconds (depending on the field, between 0.4% and 1.0% of the sources).
- ID:
- ivo://CDS.VizieR/J/ApJ/671/323
- Title:
- Spitzer Spectra of a 10mJy galaxy sample
- Short Name:
- J/ApJ/671/323
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A complete flux-limited sample of 50 galaxies is presented having f{nu}(24um)>10mJy, chosen from a survey with MIPS on Spitzer of 8.2deg^2^ in the NOAO Deep Wide-Field Survey (NDWFS) region in Bootes. Spectra obtained with the low-resolution modules of IRS on Spitzer are described for 36 galaxies in this sample; 25 show strong PAH emission features characteristic of starbursts, and 11 show silicate absorption or emission, emission lines, or featureless spectra characteristic of AGNs. Infrared or optical spectral classifications are available for 48 of the entire sample of 50; 33 galaxies are classified as starbursts and 15 as AGNs.
- ID:
- ivo://CDS.VizieR/J/ApJ/663/1149
- Title:
- Spitzer survey of Serpens YSO population
- Short Name:
- J/ApJ/663/1149
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We discuss the combined IRAC/MIPS c2d Spitzer Legacy observations of the Serpens star-forming region. We describe criteria for isolating bona fide YSOs from the extensive background of extragalactic objects. We then discuss the properties of the resulting high-confidence set of 235 YSOs. An additional 51 lower confidence YSOs outside this area are identified from the MIPS data and 2MASS photometry. We present color-color diagrams to compare our observed source properties with those of theoretical models for star/disk/envelope systems and our own modeling of the objects that are well represented by a stellar photosphere plus circumstellar disk.
- ID:
- ivo://CDS.VizieR/J/AJ/160/130
- Title:
- SpT & NIR color excess of Solar-type stars
- Short Name:
- J/AJ/160/130
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Although solar-analog stars have been studied extensively over the past few decades, most of these studies have focused on visible wavelengths, especially those identifying solar-analog stars to be used as calibration tools for observations. As a result, there is a dearth of well-characterized solar analogs for observations in the near-infrared, a wavelength range important for studying solar system objects. We present 184 stars selected based on solar-like spectral type and V-J and V-K colors whose spectra we have observed in the 0.8-4.2{mu}m range for calibrating our asteroid observations. Each star has been classified into one of three ranks based on spectral resemblance to vetted solar analogs. Of our set of 184 stars, we report 145 as reliable solar-analog stars, 21 as solar analogs usable after spectral corrections with low-order polynomial fitting, and 18 as unsuitable for use as calibration standards owing to spectral shape, variability, or features at low to medium resolution. We conclude that all but five of our candidates are reliable solar analogs in the longer wavelength range from 2.5 to 4.2{mu}m. The average colors of the stars classified as reliable or usable solar analogs are V-J=1.148, V-H=1.418, and V-K= 1.491, with the entire set being distributed fairly uniformly in R.A. across the sky between -27{deg} and +67{deg} in decl.
- ID:
- ivo://CDS.VizieR/J/AJ/132/1445
- Title:
- Standard calibration stars infrared spectra
- Short Name:
- J/AJ/132/1445
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Infrared spectra with increased spectral resolution and accuracy of the absolute infrared spectral flux have been created for a subset of stellar standards created by Cohen and his collaborators in previous papers in this series. Moderate-resolution ({lambda}/{Delta}{lambda}~400) spectroscopy obtained on infrared standard stars by the Short Wavelength Spectrometer on the Infrared Space Observatory was combined with high-quality photometry tied to our recent absolute calibration from the Midcourse Space Experiment. Thus, 1-35 micron spectra were created for 33 stars, 9 of which are Cohen et al. secondary standards and another 20 of which are tertiary standards for which Cohen adopted spectral templates. The wavelength spacing is given by (0.0001/1 micron)*lambda^2, which provides for 10,000 samples over the 1-35 micron spectral range
- ID:
- ivo://CDS.VizieR/J/A+A/468/1009
- Title:
- Star formation in Perseus. II.
- Short Name:
- J/A+A/468/1009
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Hatchell et al. (2005, Cat. <J/A+A/440/151>, Paper I) published a submillimetre continuum map of the Perseus molecular cloud, detecting the starless and protostellar cores within it. The aim is to determine the evolutionary stage of each submm core in Perseus, and investigate the lifetimes of these phases.
- ID:
- ivo://CDS.VizieR/J/ApJ/752/146
- Title:
- Star forming complexes in Galactic WMAP sources
- Short Name:
- J/ApJ/752/146
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We analyze Spitzer GLIMPSE, Midcourse Space Experiment (MSX), and Wilkinson Microwave Anisotropy Probe (WMAP) images of the Milky Way to identify 8{mu}m and free-free sources in the Galaxy. Seventy-two of the 88 WMAP sources have coverage in the GLIMPSE and MSX surveys suitable for identifying massive star-forming complexes (SFCs). We measure the ionizing luminosity functions of the SFCs and study their role in the turbulent motion of the Galaxy's molecular gas. We find a total Galactic free-free flux f_{nu}_=46177.6Jy; the 72 WMAP sources with full 8{mu}m coverage account for 34263.5Jy (~75%), with both measurements made at {nu}=94GHz (W band). We find a total of 280 SFCs, of which 168 have unique kinematic distances and free-free luminosities. We use a simple model for the radial distribution of star formation to estimate the free-free and ionizing luminosity for the sources lacking distance determinations. The total dust-corrected ionizing luminosity is Q=(2.9+/-0.5)x10^53^photons/s, which implies a Galactic star formation rate of \dot{M}_{star}_=1.2+/-0.2{M}_{sun}_/yr. We present the (ionizing) luminosity function of the SFCs and show that 24 sources emit half the ionizing luminosity of the Galaxy. The SFCs appear as bubbles in GLIMPSE or MSX images; the radial velocities associated with the bubble walls allow us to infer the expansion velocity of the bubbles. We calculate the kinetic luminosity of the bubble expansion and compare it to the turbulent luminosity of the inner molecular disk. SFCs emitting 80% of the total Galactic free-free luminosity produce a kinetic luminosity equal to 65% of the turbulent luminosity in the inner molecular disk. This suggests that the expansion of the bubbles is a major driver of the turbulent motion of the inner Milky Way molecular gas.
- ID:
- ivo://CDS.VizieR/J/ApJ/773/86
- Title:
- Star-forming galaxies in ACO 2029
- Short Name:
- J/ApJ/773/86
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Dense environments are known to quench star formation in galaxies, but it is still unknown what mechanism(s) are directly responsible. In this paper, we study the star formation of galaxies in A2029 and compare it to that of Coma, combining indicators at 24{mu}m, H{alpha}, and UV down to rates of 0.03M_{sun}_/yr. We show that A2029's star-forming galaxies follow the same mass-SFR relation as the field. The Coma cluster, on the other hand, has a population of galaxies with star formation rates (SFRs) significantly lower than the field mass-SFR relation, indicative of galaxies in the process of being quenched. Over half of these galaxies also host active galactic nuclei. Ram-pressure stripping and starvation/strangulation are the most likely mechanisms for suppressing the star formation in these galaxies, but we are unable to disentangle which is dominating. The differences we see between the two clusters' populations of star-forming galaxies may be related to their accretion histories, with A2029 having accreted its star-forming galaxies more recently than Coma. Additionally, many early-type galaxies in A2029 are detected at 24{mu}m and/or in the far-UV, but this emission is not directly related to star formation. Similar galaxies have probably been classified as star forming in previous studies of dense clusters, possibly obscuring some of the effects of the cluster environment on true star-forming galaxies.
- ID:
- ivo://CDS.VizieR/J/MNRAS/435/2861
- Title:
- Star-forming galaxies in near-IR
- Short Name:
- J/MNRAS/435/2861
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The near-infrared spectral region is becoming a very useful wavelength range to detect and quantify the stellar population of galaxies. Models are developing to predict the contribution of the thermally pulsating stars on the asymptotic giant branch stars that should dominate the near-infrared region (NIR) spectra of populations 0.3 to 2Gyr old. When present in a given stellar population, these stars leave unique signatures that can be used to detect them unambiguously. However, these models have to be tested in a homogeneous data base of star-forming galaxies, to check if the results are consistent with what is found from different wavelength ranges. In this work, we performed stellar population synthesis on the nuclear and extended regions of 23 star-forming galaxies to understand how the star formation tracers in the NIR can be used in practice. The stellar population synthesis shows that for the galaxies with strong emission in the NIR, there is an important fraction of young/intermediate population contributing to the spectra, which is probably the ionization source in these galaxies. Galaxies that had no emission lines measured in the NIR were found to have older average ages and less contribution of young populations. Although the stellar population synthesis method proved to be very effective to find the young ionizing population in these galaxies, no clear correlation between these results and the NIR spectral indexes were found. Thus, we believe that, in practice, the use of these indexes is still very limited due to observational limitations.
