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Start Over Subject infrared astronomy
271. Extinction in star-forming regions
ID:
ivo://CDS.VizieR/J/ApJ/693/L81
Title:
Extinction in star-forming regions
Short Name:
J/ApJ/693/L81
Date:
21 Oct 2021
Publisher:
CDS
Description:
Using Spitzer Infrared Spectrograph observations of G0-M4III stars behind dark clouds, I construct 5-20um empirical extinction curves for 0.3<=A_K_<7, which is equivalent to A_V_ between ~3 and 50. For A_K_<1, the curve appears similar to the Mathis diffuse interstellar medium extinction curve, but with a greater degree of extinction. For A_K_>1, the curve exhibits lower contrast between the silicate and absorption continuum, develops ice absorption, and lies closer to the Weingartner and Draine R_V_=5.5 Case B curve, a result which is consistent with that of Flaherty et al. (2007ApJ...663.1069F) and Chiar et al. (2007ApJ...666L..73C). Recently, work using Spitzer Infrared Array Camera data by Chapman et al. independently reaches a similar conclusion that the shape of the extinction curve changes as a function of increasing A_K_. By calculating the optical depths of the 9.7um silicate and 6.0, 6.8, and 15.2um ice features, I determine that a process involving ice is responsible for the changing shape of the extinction curve and speculate that this process is a coagulation of ice-mantled grains rather than ice-mantled grains alone.
272. Extinctions at 7um & 15um from ISOGAL survey
ID:
ivo://CDS.VizieR/J/A+A/446/551
Title:
Extinctions at 7um & 15um from ISOGAL survey
Short Name:
J/A+A/446/551
Date:
21 Oct 2021
Publisher:
CDS
Description:
The ISOGAL PSC data have been associated with near-infrared 2MASS sources, consisting a five-band photometric catalogue. In comparison with the ISOGAL-DENIS PSC catalogue, the number of fields in the ISOGAL-2MASS PSC is increased by 43 thanks to the 2MASS inclusion of the northern ISOGAL field. This point source catalogue contains all parameters of 7{mu}m or 15{mu}m from the ISOGAL PSC, together with the J H Ks bands data from the 2MASS All-Sky PSC (see the paper for a complete description). Based on the ISOGAL-2MASS PSC, the extinction laws at 7{mu}m and 15{mu}m are derived for more than 120 sightlines in the inner Galactic plane. The extinction values at 7{mu}m and 15{mu}m were in terms of the near-infrared extinction in the Ks band. The ratios that E(Ks-[7])/E(J-Ks) and E(Ks-[7])/E(Ks-[15]) are also displayed in the tables (see the paper for a complete description).
273. Extragalactic IRAS sources
ID:
ivo://CDS.VizieR/J/AJ/109/2318
Title:
Extragalactic IRAS sources
Short Name:
J/AJ/109/2318
Date:
21 Oct 2021
Publisher:
CDS
Description:
Extragalactic sources detected at lambda=60um were selected from the IRAS Faint Source Catalog, Version 2 (Cat. II/156) by the criterion S(60um)>=S(12um). They were identified by position coincidence with radio sources stronger than 25mJy at 4.85GHz in the 6.0sr declination band 0deg<Dec.<+75deg (excluding the 0.05sr region 12h40m<R.A.<14h40m, 0deg<Dec.<+5deg) and with radio sources stronger than 80mJy in the 3.4sr area 0h<R.A.<20h, -40deg<Dec.<0deg (plus the region 12h40m<R.A.<14h40m, 0deg<Dec.<+5deg). Fields containing new candidate identifications were mapped by the VLA at 4.86GHz with about 15" FWHM resolution. Difficult cases were confirmed or rejected with the aid of accurate (sigma~1") radio and optical positions. The final sample of 354 identifications in Omega=9.4sr is reliable and large enough to contain statistically useful numbers of radio-loud FIR galaxies and quasars. The logarithmic FIR/radio flux ratio parameter q can be used to distinguish radio sources powered by "starbursts" from those powered by "monsters." Starbursts and normal spiral galaxies in a lambda=60um flux-limited sample have a narrow (sigma_q=0.14+/-0.01) q distribution with mean <q>=2.74+/-0.01, and none have "warm" FIR spectra [{alpha}(25um, 60um)<1.5]. The absence of radio-quiet (but not completely silent) blazars indicates that nearly all blazars become optically thin at frequencies {nu}<~100GHz. Nonthermal sources with steep FIR/optical spectra and dust-embedded sources visible only at FIR and radio wavelengths must be very rare.
274. Extremely Red Objects XMM-Newton observations
ID:
ivo://CDS.VizieR/J/A+A/432/69
Title:
Extremely Red Objects XMM-Newton observations
Short Name:
J/A+A/432/69
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the results of a deep (about 80ks) XMM-Newton survey of the largest sample of near-infrared selected Extremely Red Objects (R-K>5) available to date to Ks<~19.2.
275. Faint companions around YSOs in TMC
ID:
ivo://CDS.VizieR/J/PASJ/60/209
Title:
Faint companions around YSOs in TMC
Short Name:
J/PASJ/60/209
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have conducted near-infrared spectroscopy of 26 faint objects around young stellar objects in the Taurus molecular cloud. These objects were detected during a course of near-infrared coronagraphic searches for companions around 72 young stellar objects with the Subaru Telescope and the near-infrared coronagraph CIAO (coronagraphic imager with adaptive optics). A comparison of the Subaru and HST archive images revealed that three central stars and faint companions share common proper motions, suggesting that they are physically associated with each other. None of the 26 sources show deep water absorption bands at near-infrared, except for DH Tau B. This result indicates that all of them, but DH Tau B, have a high photospheric temperature or a large amount of excess from circumstellar materials.
276. Far-infrared emission from 5 galaxy clusters
ID:
ivo://CDS.VizieR/J/ApJ/405/94
Title:
Far-infrared emission from 5 galaxy clusters
Short Name:
J/ApJ/405/94
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have analyzed IRAS image data using a random position, multiple-aperture photometry method to study diffuse far-infrared emission for a sample of 56 clusters of galaxies at 60 and 100um. Five of the clusters in the sample exhibit excess far-infrared emission, but at low levels of significance. For A496 (Perseus) and MKW 1, this emission appears to be associated with a strong point source: in A2344, the observed excess is probably due to a foreground cirrus cloud. Two clusters, A262 and A2670, show evidence for extended diffuse emission. This emission is unlikely to be due to point sources associated with the clusters. In these two clusters, the diffuse emission shows evidence of being extended along the cluster's major axis. Far-infrared maps at 60 and 100um are presented for these five clusters. We find that contamination due to diffuse Galactic cirrus represents the major source of uncertainty in the measurement of far-infrared emission. The mean cluster fluxes for the sample as a whole are 44 and 107mJy for a 4' diameter aperture at 60 and 100um, respectively. The corresponding fluxes for a 10' diameter aperture are 138 and 253mJy at 60 and 100um. Photometry for the entire sample shows statistical evidence for excess emission at 60um associated with clusters in apertures 4' and 10' in diameter. This result is unlikely to be caused by random sampling errors. The flux distributions are analyzed for evidence that excess far-infrared radiation correlates with cluster environmental characteristics. Although we find evidence that poorer X-ray clusters are stronger far-infrared emitters, this result is tentative owing to the small sample sizes involved. The far-infrared luminosities, dust temperatures, and dust masses which these results imply are also presented. Finally, the origin and possible heating mechanism for dust in the intracluster medium is discussed.
277. Far-infrared loops in the 2nd Galactic Quadrant
ID:
ivo://CDS.VizieR/J/A+A/418/131
Title:
Far-infrared loops in the 2nd Galactic Quadrant
Short Name:
J/A+A/418/131
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the results of an investigation of the large structure of the diffuse interstellar medium in the 2nd Galactic Quadrant (90{deg}<=l<=180{deg}). 145 loops were identified on IRAS based on far-infrared maps. Our catalogue lists their basic physical properties. The distribution clearly suggests that there is an efficient process that can generate loop-like features at high galactic latitudes. Distances are provided for 30 loops. We also give an observational estimate on the volume filling factor of the hot gas in the Local Arm, 4.6%<=f_2nd_<6.4%.
278. Far-IR lines in YSOs Herschel-PACS
ID:
ivo://CDS.VizieR/J/A+A/594/A59
Title:
Far-IR lines in YSOs Herschel-PACS
Short Name:
J/A+A/594/A59
Date:
21 Oct 2021
Publisher:
CDS
Description:
Gas plays a major role in the dynamical evolution of young stellar objects (YSOs). Its interaction with the dust is the key to our understanding planet formation later on in the protoplanetary disc stage. Studying the gas content is therefore a crucial step towards understanding YSO and planet formation. Such a study can be made through spectroscopic observations of emission lines in the far-infrared, where some of the most important gas coolants emit, such as the [OI] ^3^P_1_-^3^P_2_ transition at 63.18 microns. We provide a compilation of observations of far-IR lines in 362 young stellar objects covering all evolutionary stages, from Class 0 to Class III with debris discs. In the present paper we focus on [OI] and o-H_2_O emission at 63 microns. We have retrieved all the available Herschel-PACS spectroscopic observations at 63 microns that used the dominant observing mode, the chop-nod technique. We provide measurements of line fluxes for the [OI] ^3^P_1_-^3^P_2_ and o-H_2_O 8_08_-7_17_ transitions at 63 microns computed using different methods. Taking advantage of the PACS IFU, we check for spatially extended emission and further study the presence of multiple dynamical components in line emission. The final compilation consists of line and continuum fluxes at 63 microns for a total of 362 young stellar objects (YSOs). We detected [OI] line emission at 63 microns in 194 sources out of 362, and line absorption in another five sources. o-H_2_O was detected in 42 sources. We find evidence of extended [OI] emission in 77 sources, and detect 3sigma residual emission in 71 of them. The number of sources showing extended emission decays from Class 0 to Class II. We also looked for different components contributing to the line emission, and found evidence for multiple components in 30 sources. We explored correlations between line emission and continuum emission and find a clear correlation between WISE fluxes from 4.6 to 22 microns and [OI] line emission. We conclude that the observed emission is typically a combination of disc/envelope and jet emission.
279. Far-IR spectrum of ethylene oxide (CH_2_-O-CH_2_)
ID:
ivo://CDS.VizieR/J/ApJ/753/18
Title:
Far-IR spectrum of ethylene oxide (CH_2_-O-CH_2_)
Short Name:
J/ApJ/753/18
Date:
21 Oct 2021
Publisher:
CDS
Description:
High-resolution Fourier Transform Infrared spectroscopy (FTIR) spectra of ethylene oxide (CH_2_-O-CH_2_) have been measured in the far-infrared region using synchrotron radiation. A total of 1182 lines between 15/cm (450GHz) and 73/cm (2.2THz) were assigned, with J_max_=64, expanding upon previous studies that had recorded spectra up to 12/cm, J_max_=49. All available data were co-fitted to provide greatly improved rotational constants for the ground vibrational state that are capable of predicting transitions up to 73/cm.
280. FEEDBACK from the NGC7538 HII region
ID:
ivo://CDS.VizieR/J/A+A/659/A77
Title:
FEEDBACK from the NGC7538 HII region
Short Name:
J/A+A/659/A77
Date:
14 Mar 2022 07:43:25
Publisher:
CDS
Description:
The interaction of expanding HII regions with their environmental cloud is one of the central questions driving the SOFIA legacy program FEEDBACK. We want to understand the interaction of the prototypical NGC7538 HII region with the neighboring molecular cloud hosting several active star-forming regions. Using the Stratospheric Observatory for Infrared Astronomy (SOFIA), we mapped an area of ~210'^2^ (~125pc^2^) around NGC7538 in the velocity-resolved ionized carbon fine-structure line [CII] at 1.9THz (158um). Complementary observed atomic carbon [CI] at 492GHz and high-J CO(8-7) data, as well as the archival near- and far-infrared, cm continuum, CO(3-2), and HI data are folded into the analysis. The ionized carbon [CII] data reveal rich morphological and kinematic structures. While the overall morphology follows the general ionized gas that is also visible in the radio continuum emission, the channel maps show multiple bubble-like structures with sizes on the order of ~80-100'' (~1.0-1.28pc). While at least one of them may be an individual feedback bubble driven by the main exciting sources of the NGC7538 HII region (the O3 and O9 stars IRS6 and IRS5), the other bubble-like morphologies may also be due to the intrinsically porous structure of the HII region. An analysis of the expansion velocities around 10km/s indicates that thermal expansion is not sufficient but that wind-driving from the central O-stars is required. The region exhibits a general velocity gradient across, but we also identify several individual velocity components. The most blue-shifted [CII] component has barely any molecular or atomic counterparts. At the interface to the molecular cloud, we find a typical photon-dominated region (PDR) with a bar-shape. Ionized C+, atomic C0 and molecular carbon CO show a layered structure in this PDR. The carbon in the PDR is dominated by its ionized C+ form with atomic C0 and molecular CO masses of ~0.45+/-0.1M_{sun}_ and ~1.2+/-0.1M_{sun}_, respectively, compared to the ionized carbon C+ in the range of 3.6-9.7M_{sun}_. This bar-shaped PDR exhibits a velocity-gradient across, indicating motions along the line of sight toward the observer. Even if it is shown to be dominated by two nearby exciting sources (IRS6 and IRS5), the NGC7538 HII region exhibits a diverse set of substructures that interact with each other as well as with the adjacent cloud. Compared to other recent [CII] observations of HII regions (e.g., Orion Veil, RCW120, RCW49), the bubble-shape morphologies revealed in [CII] emission that are indicative of expanding shells are recurring structures of PDRs.