- ID:
- ivo://CDS.VizieR/J/A+A/655/A12
- Title:
- LMC N113 and N159W ALMA para-H_2_CO datacubes
- Short Name:
- J/A+A/655/A12
- Date:
- 07 Mar 2022 07:15:12
- Publisher:
- CDS
- Description:
- We mapped the kinetic temperature structure of two massive star-forming regions, N113 and N159W, in the Large Magellanic Cloud (LMC). We have used ~1.6" (~0.4pc) resolution measurements of the para-H_2_CO J_KaKc_=3_03_-2_02_, 3_22_-2_21_, and 3_21_-2_20_ transitions near 218.5GHz to constrain RADEX non local thermodynamic equilibrium models of the physical conditions. The gas kinetic temperatures derived from the para-H_2_CO line ratios 3_22_-2_21_/3_03_-2_02_ and 3_21_-2_20_/3_03_-2_02_ range from 28 to 105K in N113 and 29 to 68K in N159W. Distributions of the dense gas traced by para-H_2_CO agree with those of the 1.3mm dust and Spitzer 8.0um emission, but they do not significantly correlate with the H emission. The high kinetic temperatures (T_kin_>~50K) of the dense gas traced by para-H_2_CO appear to be correlated with the embedded infrared sources inside the clouds and/or young stellar objects in the N113 and N159W regions. The lower temperatures (T_kin_<50K) were measured at the outskirts of the H_2_CO-bearing distributions of both N113 and N159W. It seems that the kinetic temperatures of the dense gas traced by para-H_2_CO are weakly affected by the external sources of the H{alpha} emission. The non thermal velocity dispersions of para-H_2_CO are well correlated with the gas kinetic temperatures in the N113 region, implying that the higher kinetic temperature traced by para-H_2_CO is related to turbulence on a ~0.4pc scale. The dense gas heating appears to be dominated by internal star formation activity, radiation, and/or turbulence. It seems that the mechanism heating the dense gas of the star-forming regions in the LMC is consistent with that in Galactic massive star-forming regions located in the Galactic plane.
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- ID:
- ivo://CDS.VizieR/J/A+A/621/A62
- Title:
- 4 LMC SFRs velocity profile maps
- Short Name:
- J/A+A/621/A62
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The aim of our study is to investigate the physical properties of the star-forming interstellar medium (ISM) in the Large Magellanic Cloud (LMC) by separating the origin of the emission lines spatially and spectrally. The LMC provides a unique local template to bridge studies in the Galaxy and high redshift galaxies because of its low metallicity and proximity, enabling us to study the detailed physics of the ISM in spatially resolved individual star-forming regions. Following Okada et al. (2015A&A...580A..54O), we investigate different phases of the ISM traced by carbon-bearing species in four star-forming regions in the LMC, and model the physical properties using the KOSMA-{tau} PDR model. We mapped 3-13 arcmin^2^ areas in 30 Dor, N158, N160, and N159 along the molecular ridge of the LMC in [C II] 158 {mu}m with GREAT on board SOFIA. We also observed the same area with CO(2-1) to (6-5), ^13^CO(2-1) and (3-2), [C I] ^3^P_1_-^3^P_0_ and ^3^P_2_-^3^P_1_ with APEX. For selected positions in N159 and 30 Dor, we observed [O I] 145 {mu}m and [O I] 63 {mu}m with upGREAT. All spectra are velocity resolved. In all four star-forming regions, the line profiles of CO, ^13^CO, and [C I] emission are similar, being reproduced by a combination of Gaussian profiles defined by CO(3-2), whereas [C II] typically shows wider line profiles or an additional velocity component. At several positions in N159 and 30 Dor, we observed the velocity-resolved [O I] 145 and 63 {mu}m lines for the first time. At some positions, the [O I] line profiles match those of CO, at other positions they are more similar to the [C II] profiles. We interpret the different line profiles of CO, [C II] and [O I] as contributions from spatially separated clouds and/or clouds in different physical phases, which give different line ratios depending on their physical properties. We modeled the emission from the CO, [C I], [C II], and [O I] lines and the far-infrared continuum emission using the latest KOSMA-{tau} PDR model, which treats the dust-related physics consistently and computes the dust continuum SED together with the line emission of the chemical species. We find that the line and continuum emissions are not well-reproduced by a single clump ensemble. Toward the CO peak at N159 W, we propose a scenario that the CO, [C II], and [O I] 63 {mu}m emission are weaker than expected because of mutual shielding among clumps.
- ID:
- ivo://CDS.VizieR/J/ApJ/897/41
- Title:
- Lyman Continuum in 111 GOODS and ERS galaxies
- Short Name:
- J/ApJ/897/41
- Date:
- 11 Mar 2022
- Publisher:
- CDS
- Description:
- We present our analysis of the Lyman continuum (LyC) emission and escape fraction of 111 spectroscopically verified galaxies with and without active galactic nuclei (AGN) from 2.26<z<4.3. We extended our ERS sample from Smith et al. with 64 galaxies in the GOODS North and South fields using WFC3/UVIS F225W, F275W, and F336W mosaics we independently drizzled using the HDUV, CANDELS, and UVUDF data. Among the 17 AGN from the 111 galaxies, one provided a LyC detection in F275W at m_AB_=23.19mag (signal-to-noise ratio, S/N~133) and GALEX NUV at m_AB_=23.77mag (S/N~13). We simultaneously fit SDSS and Chandra spectra of this AGN to an accretion disk and Comptonization model, and find f_esc_ values of f_esc_^F275W^~28_-4_^+20^% and f_esc_^NUV^~30_-5_^+22^% . For the remaining 110 galaxies, we stack image cutouts that capture their LyC emission using the F225W, F275W, and F336W data of the GOODS and ERS samples, and both combined, as well as subsamples of galaxies with and without AGN, and all galaxies. We find the stack of 17 AGN dominate the LyC production from <z>~2.3-4.3 by a factor of ~10 compared to all 94 galaxies without AGN. While the IGM of the early universe may have been reionized mostly by massive stars, there is evidence that a significant portion of the ionizing energy came from AGN.
- ID:
- ivo://CDS.VizieR/J/ApJS/243/13
- Title:
- Massive star-forming clump from MALT90
- Short Name:
- J/ApJS/243/13
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We selected 90 massive star-forming clumps with strong N2H+(1-0), HCO+(1-0), HCN(1-0), and HNC(1-0) emission from the Millimetre Astronomy Legacy Team 90 GHz survey. We obtained Herschel data for all 90 sources and NRAO VLA Sky Survey data for 51 of them. We convolved and regridded all images to the same resolution and pixel size and derived the temperature, H2 column density, molecules' abundances and abundance, and ratios of each pixel. Our analysis yields three main conclusions. First, the abundances of N2H+, HCO+, HCN, and HNC increase when the column density decreases and the temperature increases, with spatial variations in their abundances dominated by changes in the H2 column density. Second, the abundance ratios between N2H+, HCO+, HCN, and HNC also display systemic variations as a function of the column density due to the chemical properties of these molecules. Third, the sources associated with the 20cm continuum emission can be classified into four types based on the behavior of the abundances of the four molecules considered here as a function of this emission. The variations of the first three types could also be attributed to the variation of the H2 column density.
- ID:
- ivo://CDS.VizieR/J/ApJ/864/136
- Title:
- Massive star-forming regions multiwavelength study
- Short Name:
- J/ApJ/864/136
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a multiwavelength study of 28 Galactic massive star-forming HII regions. For 17 of these regions, we present new distance measurements based on Gaia DR2 parallaxes. By fitting a multicomponent dust, blackbody, and power-law continuum model to the 3.6{mu}m through 10mm spectral energy distributions, we find that ~34% of Lyman continuum photons emitted by massive stars are absorbed by dust before contributing to the ionization of HII regions, while ~68% of the stellar bolometric luminosity is absorbed and reprocessed by dust in the HII regions and surrounding photodissociation regions. The most luminous, infrared-bright regions that fully sample the upper stellar initial mass function (ionizing photon rates N_C_>=10^50^s^-1^ and dust-processed L_TIR_>=10^6.8^L_{sun}_) have on average higher percentages of absorbed Lyman continuum photons (~51%) and reprocessed starlight (~82%) compared to less luminous regions. Luminous HII regions show lower average polycyclic aromatic hydrocarbon (PAH) fractions than less luminous regions, implying that the strong radiation fields from early-type massive stars are efficient at destroying PAH molecules. On average, the monochromatic luminosities at 8, 24, and 70{mu}m combined carry 94% of the dust-reprocessed L_TIR_. L70 captures ~52% of L_TIR_, and is therefore the preferred choice to infer the bolometric luminosity of dusty star-forming regions. We calibrate star formation rates (SFRs) based on L24 and L70 against the Lyman continuum photon rates of the massive stars in each region. Standard extragalactic calibrations of monochromatic SFRs based on population synthesis models are generally consistent with our values.
- ID:
- ivo://CDS.VizieR/J/other/Sci/359.69
- Title:
- Massive stars in 30 Dor
- Short Name:
- J/other/Sci/359.
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The 30 Doradus star-forming region in the Large Magellanic Cloud is a nearby analog of large star-formation events in the distant universe. We determined the recent formation history and the initial mass function (IMF) of massive stars in 30 Doradus on the basis of spectroscopic observations of 247 stars more massive than 15 solar masses (M_{sun}_). The main episode of massive star formation began about 8 million years (My) ago, and the star-formation rate seems to have declined in the last 1My. The IMF is densely sampled up to 200 Embedded Image and contains 32+/-12% more stars above 30M_{sun}_ than predicted by a standard Salpeter IMF. In the mass range of 15 to 200M_{sun}_, the IMF power-law exponent is 190^+0.37^_-0.26_, shallower than the Salpeter value of 2.35.
- ID:
- ivo://CDS.VizieR/J/AJ/159/282
- Title:
- Membership in Ophiuchus & Upper Scorpius complex
- Short Name:
- J/AJ/159/282
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have performed a survey for new members of the Ophiuchus cloud complex using high-precision astrometry from the second data release of Gaia, proper motions measured with multi-epoch images from the Spitzer Space Telescope, and color-magnitude diagrams constructed with photometry from various sources. Through spectroscopy of candidates selected with those data, we have identified 155 new young stars. Based on available measurements of kinematics, we classify 102, 47, and 6 of those stars as members of Ophiuchus, Upper Sco, and other populations in Sco-Cen, respectively. We have also assessed the membership of all other stars in the vicinity of Ophiuchus that have spectroscopic evidence of youth from previous studies, arriving at a catalog of 373 adopted members of the cloud complex. For those adopted members, we have compiled mid-infrared photometry from Spitzer and the Wide-field Infrared Survey Explorer and have used mid-infrared colors to identify and classify circumstellar disks. We find that 210 of the members show evidence of disks, including 48 disks that are in advanced stages of evolution. Finally, we have estimated the relative median ages of the populations near the Ophiuchus clouds and the surrounding Upper Sco association using absolute K-band magnitudes (MK) based on Gaia parallaxes. If we adopt an age 10Myr for Upper Sco, then the relative values of MK imply median ages of ~2Myr for L1689 and embedded stars in L1688, 3-4Myr for low-extinction stars near L1688, and ~6Myr for the group containing {rho}Oph.
- ID:
- ivo://CDS.VizieR/J/A+A/635/A111
- Title:
- M16 SITELLE datacube
- Short Name:
- J/A+A/635/A111
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the very first wide-field, 11' by 11', optical spectral mapping of M16, one of the most famous star-forming regions in the Galaxy. The data were acquired with the new imaging Fourier transform spectrograph SITELLE mounted on the Canada-France-Hawaii Telescope (CFHT). We obtained three spectral cubes with a resolving power of 10000 (SN1 filter), 1500(SN2 filter) and 600 (SN3 filter), centered on the iconic Pillars of Creation and the HH 216 flow, covering the main optical nebular emission lines, namely [OII]{lambda}3726,29 (SN1), H{beta}, [OIII]{lambda}4959,5007 (SN2), [NII]{lambda}6548,84, H{alpha}, and [SII]{lambda}6717,31 (SN3). We validate the performance, calibration, and data reduction of SITELLE, and analyze the structures in the large field-of-view in terms of their kinematics and nebular emission. We compared the SITELLE data to MUSE integral field observations and other spectroscopic and narrow-band imaging data to validate the performance of SITELLE. We computed gas-phase metallicities via the strong-line method, performed a pixel-by-pixel fit to the main emission lines to derive kinematics of the ionized gas, computed the mass-loss rate of the Eastern pillar (also known as the Spire), and combined the SITELLE data with near-infrared narrow-band imaging to characterize the HH 216 flow. The comparison with previously published fluxes demonstrates very good agreement. We disentangle the dependence of the gas-phase metallicities (derived via abundance-tracing line ratios) on the degree of ionization and obtain metallicities that are in excellent agreement with the literature. We confirm the bipolar structure of HH216, find evidence for episodic accretion from the source of the flow, and identify its likely driving source. We compute the mass-loss rate of the Spire pillar on the East side of the HII region and find excellent agreement with the correlation between the mass-loss rate and the ionizing photon flux from the nearby cluster NGC6611.
- ID:
- ivo://CDS.VizieR/J/AJ/158/54
- Title:
- New Taurus members from stellar to planetary masses
- Short Name:
- J/AJ/158/54
- Date:
- 06 Dec 2021 11:31:43
- Publisher:
- CDS
- Description:
- We present a large sample of new members of the Taurus star-forming region that extend from stellar to planetary masses. To identify candidate members at substellar masses, we have used color-magnitude diagrams and proper motions measured with several wide-field optical and infrared (IR) surveys. At stellar masses, we have considered the candidate members that were found in a recent analysis of high-precision astrometry from the Gaia mission. Using new and archival spectra, we have measured spectral types and assessed membership for these 161 candidates, 79 of which are classified as new members. Our updated census of Taurus now contains 519 known members. According to Gaia data, this census should be nearly complete for spectral types earlier than M6-M7 at A_J_<1. For a large field encompassing ~72% of the known members, the census should be complete for K<15.7 at A_J_<1.5, which corresponds to ~5-13 M_Jup_ for ages of 1-10 Myr based on theoretical evolutionary models. Our survey has doubled the number of known members at >=M9 and has uncovered the faintest known member in M_K_, which should have a mass of ~3-10 M_Jup_ for ages of 1-10 Myr. We have used mid-IR photometry from the Spitzer Space Telescope and the Wide-field Infrared Survey Explorer to determine whether the new members exhibit excess emission that would indicate the presence of circumstellar disks. The updated disk fraction for Taurus is ~0.7 at =<M3.5 and ~0.4 at >M3.5.
- ID:
- ivo://CDS.VizieR/J/MNRAS/478/3693
- Title:
- N in Galactic high-mass star-forming cores
- Short Name:
- J/MNRAS/478/3693
- Date:
- 10 Dec 2021 00:14:43
- Publisher:
- CDS
- Description:
- The fractionation of nitrogen (N) in star-forming regions is a poorly understood process. To put more stringent observational constraints on the N-fractionation, we have observed with the IRAM-30-m telescope a large sample of 66 cores in massive star-forming regions. We targeted the (1-0) rotational transition of HN^13^C, HC^15^N, H^13^CN and HC^15^N, and derived the ^14^N/^15^N ratio for both HCN and HNC. We have completed this sample with that already observed by Colzi et al., and thus analysed a total sample of 87 sources. The ^14^N/^15^N ratios are distributed around the Proto-Solar Nebula value with a lower limit near the TA value (~272). We have also derived the ^14^N/^15^N ratio as a function of the Galactocentric distance and deduced a linear trend based on unprecedented statistics. The Galactocentric dependences that we have found are consistent, in the slope, with past works but we have found a new local ^14^N/^15^N value of ~400, i.e. closer to the Prosolar Nebula value. A second analysis was done, and a parabolic Galactocentric trend was found. Comparison with Galactic chemical evolution models shows that the slope until 8 kpc is consistent with the linear analysis, while the flattening trend above 8 kpc is well reproduced by the parabolic analysis.
