- ID:
- ivo://CDS.VizieR/J/ApJ/630/381
- Title:
- Mid-IR imaging in {rho} Oph
- Short Name:
- J/ApJ/630/381
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Results of a comprehensive, new, ground-based mid-infrared imaging survey of the young stellar population of the {rho} Ophiuchi cloud are presented. Data were acquired at the Palomar 5m and at the Keck 10m telescopes with the MIRLIN (Mid-InfraRed Large-well Imager) and LWS (Long Wavelength Spectrometer centered at 12.5{mu}m) instruments, at 0.5" and 0.25" resolutions, respectively. Of 172 survey objects, 85 were detected. Among the 22 multiple systems observed, 15 were resolved and their individual component fluxes determined.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/719/1191
- Title:
- Mid-IR indicators of SF and AGN in galaxies
- Short Name:
- J/ApJ/719/1191
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate the use of mid-infrared (MIR) polycyclic aromatic hydrocarbon (PAH) bands, the continuum, and emission lines as probes of star formation (SF) and active galactic nucleus (AGN) activity in a sample of 100 "normal" and local (z~0.1) emission-line galaxies. The MIR spectra were obtained with the Spitzer Space Telescope Infrared Spectrograph as part of the Spitzer-SDSS-GALEX Spectroscopic Survey (SSGSS), which includes multi-wavelength photometry from the ultraviolet to the far-infrared and optical spectroscopy. The continuum and features were extracted using PAHFIT, a decomposition code which we find to yield PAH equivalent widths (EWs) up to ~30 times larger than the commonly used spline methods. Despite the lack of extreme objects in our sample (such as strong AGNs, low-metallicity galaxies, or ULIRGs), we find significant variations in PAH, continuum, and emission-line properties, and systematic trends between these MIR properties and optically derived physical properties, such as age, metallicity, and radiation field hardness. We revisit the diagnostic diagram relating PAH EWs and [NeII]12.8um/[OIV]25.9um line ratios and find it to be in much better agreement with the standard optical SF/AGN classification than when spline decompositions are used, while also potentially revealing obscured AGNs.
- ID:
- ivo://CDS.VizieR/J/AJ/129/1534
- Title:
- Mid-IR photometry in the Orion Nebula
- Short Name:
- J/AJ/129/1534
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present two wide-field (~5'x3.5'), diffraction-limited ({lambda}/D~0.5" at 10{mu}m), broadband 10 and 20{mu}m images of the Orion Nebula, plus six 7-13{mu}m narrowband images of the BN/KL complex taken at the 3.8m UKIRT telescope with the MPIA MAX camera.
- ID:
- ivo://CDS.VizieR/J/A+A/622/A135
- Title:
- Mid-J CO emission of Top100 clumps
- Short Name:
- J/A+A/622/A135
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- High-mass stars are formed within massive molecular clumps, where a large number of stars form close together. The evolution of the clumps with different masses and luminosities is mainly regulated by their high-mass stellar content and the formation of such objects is still not well understood. In this work, we characterise the mid-J CO emission in a statistical sample of 99 clumps (TOP100) selected from the ATLASGAL survey that are representative of the Galactic proto-cluster population. High-spatial resolution APEX-CHAMP+ maps of the CO (6-5) and CO (7-6) transitions were obtained and combined with additional single-pointing APEX-FLASH+ spectra of the CO (4-3) line. The data were convolved to a common angular resolution of 13.4". We analysed the line profiles by fitting the spectra with up to three Gaussian components, classified as narrow or broad, and computed CO line luminosities for each transition. Additionally, we defined a distance-limited sample of 72 sources within 5kpc to check the robustness of our analysis against beam dilution effects. We have studied the correlations of the line luminosities and profiles for the three CO transitions with the clump properties and investigate if and how they change as a function of the evolution. All sources were detected above 3-{sigma} in all three CO transitions and most of the sources exhibit broad CO emission likely associated with molecular outflows. We find that the extension of the mid-J CO emission is correlated with the size of the dust emission traced by the Herschel-PACS 70um maps. The CO line luminosity (LCO) is correlated with the luminosity and mass of the clumps. However, it does not correlate with the luminosity-to-mass ratio. The dependency of the CO luminosity with the properties of the clumps is steeper for higher-J transitions. Our data seem to exclude that this trend is biased by self-absorption features in the CO emission, but rather suggest that different J transitions arise from different regions of the inner envelope. Moreover, high-mass clumps show similar trends in CO luminosity as lower mass clumps, but are systematically offset towards larger values, suggesting that higher column density and (or) temperature (of unresolved) CO emitters are found inside high-mass clumps.
- ID:
- ivo://CDS.VizieR/J/ApJ/834/57
- Title:
- Milky Way molecular clouds from ^12^CO
- Short Name:
- J/ApJ/834/57
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This study presents a catalog of 8107 molecular clouds that covers the entire Galactic plane and includes 98% of the ^12^CO emission observed within b+/-5^{deg}^. The catalog was produced using a hierarchical cluster identification method applied to the result of a Gaussian decomposition of the Dame+ (2001ApJ...547..792D) data. The total H_2_ mass in the catalog is 1.2x10^9^M_{sun}_, in agreement with previous estimates. We find that 30% of the sight lines intersect only a single cloud, with another 25% intersecting only two clouds. The most probable cloud size is R~30pc. We find that M{propto}R^2.2+/-0.2^, with no correlation between the cloud surface density, {Sigma}, and R. In contrast with the general idea, we find a rather large range of values of {Sigma}, from 2 to 300M_{sun}_/pc^2^, and a systematic decrease with increasing Galactic radius, R_gal_. The cloud velocity dispersion and the normalization {sigma}_0_={sigma}_v_/R^1/2^ both decrease systematically with R_gal_. When studied over the whole Galactic disk, there is a large dispersion in the line width-size relation and a significantly better correlation between {sigma}_v_ and {Sigma}R. The normalization of this correlation is constant to better than a factor of two for R_gal_<20kpc. This relation is used to disentangle the ambiguity between near and far kinematic distances. We report a strong variation of the turbulent energy injection rate. In the outer Galaxy it may be maintained by accretion through the disk and/or onto the clouds, but neither source can drive the 100 times higher cloud-averaged injection rate in the inner Galaxy.
- ID:
- ivo://CDS.VizieR/J/MNRAS/488/1141
- Title:
- Milky Way Project DR2 bubbles & bow shocks
- Short Name:
- J/MNRAS/488/1141
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Citizen science has helped astronomers comb through large data sets to identify patterns and objects that are not easily found through automated processes. The Milky Way Project (MWP), a citizen science initiative on the Zooniverse platform, presents internet users with infrared (IR) images from Spitzer Space Telescope Galactic plane surveys. MWP volunteers make classification drawings on the images to identify targeted classes of astronomical objects. We present the MWP second data release (DR2) and an updated data reduction pipeline written in Python. We aggregate 3 million classifications made by MWP volunteers during the years 2012-2017 to produce the DR2 catalogue, which contains 2600 IR bubbles and 599 candidate bow-shock driving stars. The reliability of bubble identifications, as assessed by comparison to visual identifications by trained experts and scoring by a machine-learning algorithm, is found to be a significant improvement over DR1. We assess the reliability of IR bow shocks via comparison to expert identifications and the colours of candidate bow-shock driving stars in the 2MASS point-source catalogue. We hence identify highly-reliable subsets of 1394 DR2 bubbles and 453 bow-shock driving stars. Uncertainties on object coordinates and bubble size/shape parameters are included in the DR2 catalog. Compared with DR1, the DR2 bubbles catalogue provides more accurate shapes and sizes. The DR2 catalogue identifies 311 new bow shock driving star candidates, including three associated with the giant HII regions NGC 3603 and RCW 49.
- ID:
- ivo://CDS.VizieR/J/ApJS/145/329
- Title:
- Millennium Arecibo 21-cm Survey
- Short Name:
- J/ApJS/145/329
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We review the theory of measuring spectral lines in emission/ absorption observations and apply it to a new survey of the 21-cm line against 79 continuum sources. We develop an observing technique and least-squares procedure to determine the opacity profile, the expected emission profile, and their uncertainty profiles. We discuss the radiative transfer for the two-component interstellar HI gas and use Gaussian components, separate ones for the warm and cold neutral media (WNM and CNM), as a practical implementation of a simple but physically correct model that successfully treats both simple and complicated profiles.
- ID:
- ivo://CDS.VizieR/J/A+A/602/A37
- Title:
- Millimeter RRL in ATLASGAL-selected massive clumps
- Short Name:
- J/A+A/602/A37
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Observations of millimeter wavelength radio recombination lines (mm-RRLs) are used to search for HII regions in an unbiased way that is complementary to many of the more traditional methods previously used (e.g., radio continuum, far-infrared colors, maser emission). The mm-RRLs can be used to derive physical properties of HII regions and to provide velocity information of ionized gas. We carried out targeted mm-RRL observations (39<= principal quantum number (n) <=65 and {Delta}n = 1, 2, 3, and 4, named Hn{alpha}, Hn{beta}, Hn{gamma}, and Hn{delta}) using the IRAM 30m and Mopra 22m telescopes. In total, we observed 976 compact dust clumps selected from a catalog of ~10000 sources identified by the APEX Telescope Large Area Survey of the Galaxy (ATLASGAL). The sample was selected to ensure a representative mix of star-forming and quiescent clumps such that a variety of different evolutionary stages is represented. Approximately half of the clumps are mid-infrared quiet while the other half are mid-infrared bright. We detected Hn{alpha} mm-RRL emission toward 178 clumps; Hn{beta}, Hn{gamma}, and Hn{delta} were also detected toward 65, 23, and 22 clumps, respectively. This is the largest sample of mm-RRLs detections published to date. Comparing the positions of these clumps with radio continuum surveys we identified compact radio counterparts for 134 clumps, confirming their association with known HII regions. The nature of the other 44 detections is unclear, but 8 detections are thought to be potentially new HII regions while the mm-RRL emission from the others may be due to contamination from nearby evolved HII regions. Broad linewidths are seen toward nine clumps (linewidth>40km/s) revealing significant turbulent motions within the ionized gas; in the past, such wide linewidths were found toward very compact and dense HII regions. We find that the systemic velocity of the associated dense molecular gas, traced by H^13^CO^+^(1-0), is consistent with the mm-RRL velocities and confirms them as embedded HII regions. We also find that the linewidth of the H^13^CO^+^(1-0) emission is significantly wider than those without mm-RRL detection, indicating a physical connection between the embedded H II region and their natal environments. We also find a correlation between the integrated fluxes of the mm-RRLs and the 6cm continuum flux densities of their radio counterparts (the correlation coefficient, {rho}, is 0.70). By calculating the electron densities we find that the mm-RRL emission is associated with HII regions with n_e_<10^5^cm^3^ and HII region diameter >0.03pc. We detected mm-RRLs toward 178 clumps and identified eight new HII region candidates. The broad mm-RRL from nine clumps may indicate that they arise in very young hyper-compact HII regions. The mm-RRLs trace the radio continuum sources detected by high-resolution observations and their line parameters show associations with the embedded radio sources and their parental molecular clumps.
- ID:
- ivo://CDS.VizieR/J/A+A/591/A75
- Title:
- Millimeter wave spectrum of methyl cyanate
- Short Name:
- J/A+A/591/A75
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The recent discovery of methyl isocyanate (CH_3_NCO) in Sgr B2(N) and Orion KL makes methyl cyanate (CH_3_OCN) a potential molecule in the interstellar medium. The aim of this work is to fulfill the first requirement for its unequivocal identification in space, i.e. the availability of transition frequencies with high accuracy. The room-temperature rotational spectrum of methyl cyanate was recorded in the millimeter wave domain from 130 to 350GHz. All rotational transitions revealed A-E splitting owing to methyl internal rotation and were globally analyzed using the ERHAM program. The data set for the ground torsional state of methyl cyanate exceeds 700 transitions within J"=10-35 and K"a=0-13 and newly derived spectroscopic constants reproduce the spectrum close to the experimental uncertainty. Spectral features of methyl cyanate were then searched for in Orion KL, Sgr B2(N), B1-b, and TMC-1 molecular clouds. Upper limits to the column density of methyl cyanate are provided.
- ID:
- ivo://CDS.VizieR/J/A+A/577/A91
- Title:
- Millimeter wave spectrum of vinyl acetate
- Short Name:
- J/A+A/577/A91
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The recent discovery of methyl acetate in Orion KL makes vinyl acetate, CH3-(C=O)-O-CH=CH2, a potential molecule in the interstellar medium.We obtained very accurate spectroscopic constants in a comprehensive laboratory analysis of its rotational spectra which can be used to predict those transition frequencies towards interstellar sources. We present the experimental study and theoretical analysis of the ground torsional state of vinyl acetate in a large spectral range for astrophysical use. The room-temperature rotational spectrum of vinyl acetate has been measured from 125 to 305GHz to provide direct frequencies to the astronomical community. Additional measurements have also been made using a broadband CP-FTMWspectrometer in the region of 6 - 18 GHz. Transition lines, corresponding to the most stable conformer, have been observed and assigned. All the rotational transitions revealed the A-E splitting due to the methyl internal rotation and had to be treated with a specific internal rotation code (BELGI-Cs). We analyzed 2508 transitions up to J"=75 for vt=0 for the most stable conformer of vinyl acetate. The new lines were globally fitted with previously published data and 24 parameters of the Hamiltonian were accurately determined. The spectral features of vinyl acetate were then searched for in Orion KL. Using the whole line survey of Orion KL (80-280GHz) obtained with the IRAM 30m radio telescope we can provide only an upper limit to the column density of vinyl acetate. However, using the ALMA Science Verification data we obtain a tentative detection of this species that will require further search at other frequencies to confirm its presence in this high mass star forming region.
