- ID:
- ivo://CDS.VizieR/J/MNRAS/442/3565
- Title:
- L-{sigma} relation for massive star formation
- Short Name:
- J/MNRAS/442/3565
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The validity of the emission-line luminosity versus ionized gas velocity dispersion (L-{sigma}) correlation for HII galaxies (HIIGx) and its potential as an accurate distance estimator are assessed. For a sample of 128 local (0.02<~z<~0.2) compact HIIGx with high equivalent widths of their Balmer emission lines, we obtained the ionized gas velocity dispersion from high signal-to-noise ratio (S/N) high-dispersion spectroscopy (Subaru High Dispersion Spectrograph (HDS) and European Southern Observatory (ESO) Very Large Telescope Ultraviolet and Visual Echelle Spectrograph (VLT-UVES)) and integrated H{beta} fluxes from low-dispersion wide aperture spectrophotometry. We find that the L(H{beta})-{sigma} relation is strong and stable against restrictions in the sample (mostly based on the emission-line profiles). The `Gaussianity' of the profile is important for reducing the root-mean-square (rms) uncertainty of the distance indicator, but at the expense of substantially reducing the sample. By fitting other physical parameters into the correlation, we are able to decrease the scatter significantly without reducing the sample. The size of the star-forming region is an important second parameter, while adding the emission-line equivalent width or the continuum colour and metallicity produces the solution with the smallest rms scatter={delta}logL(H{beta})=0.233. The derived coefficients in the best L(H{beta})-{sigma} relation are very close to what is expected from virialized ionizing clusters, while the derived sum of the stellar and ionized gas masses is similar to the dynamical mass estimated using the Hubble Space Telescope} (HST}) corrected Petrosian radius. These results are compatible with gravity being the main mechanism causing the broadening of the emission lines in these very young and massive clusters. The derived masses range from about 2x10^6^M_{sun}_ to 10^9^M_{sun}_ and their 'corrected' Petrosian radius ranges from a few tens to a few hundred pc.
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Search Results
- ID:
- ivo://CDS.VizieR/VII/9
- Title:
- Lynds' Catalogue of Bright Nebulae
- Short Name:
- VII/9
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Catalogue of Bright Nebulae lists the galactic and equatorial coordinates of the center of the cloud, the dimensions of the nebulae as measured on the photograph on which it appeared at its brightest, the area of nebulosity in square degrees, color as compared between the blue and red Palomar plates, a brightness index on a scale of 6, an identification number that indicates the complexity of the nebulosity, and a cross reference to NGC (Cat. <VII.1>), Index Catalogue (IC), Sharpless (1959) Catalogue of HII Regions (Cat. <VII/20>), Cederblad (1956) Catalogue of Diffuse Galactic Nebulae, and Dorschner and Gurtler (1963).
313. MAGPIS 20cm survey
- ID:
- ivo://CDS.VizieR/J/AJ/131/2525
- Title:
- MAGPIS 20cm survey
- Short Name:
- J/AJ/131/2525
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the Multi-Array Galactic Plane Imaging Survey (MAGPIS), which maps portions of the first Galactic quadrant with an angular resolution, sensitivity, and dynamic range that surpass existing radio images of the Milky Way by more than an order of magnitude. The source detection threshold at 20cm is in the range 12mJy over the 85% of the survey region (5{deg}<l<32{deg}, |b|<0.8{deg}) not covered by bright extended emission; the angular resolution is ~6". We catalog over 3000 discrete sources (diameters mostly <30") and present an atlas of ~400 diffuse emission regions. New and archival data at 90cm for the whole survey area are also presented. Comparison of our catalogs and images with the Midcourse Space Experiment mid-infrared data allows us to provide preliminary discrimination between thermal and nonthermal sources. We identify 49 high-probability supernova remnant candidates, increasing by a factor of 7 the number of known remnants with diameters smaller than 5' in the survey region; several are pulsar wind nebula candidates and/or very small diameter remnants (D<45").
- ID:
- ivo://CDS.VizieR/J/A+A/626/A28
- Title:
- M8 and Her 36 C_2_H and c-C_3_H_2_ data
- Short Name:
- J/A+A/626/A28
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Hydrocarbons are ubiquitous in the interstellar medium, but their formation is still not well understood, depending on the physical environment they are found in. Messier 8 (M8) is host to one of the brightest Hii regions and photodissociation regions (PDRs) in our galaxy. With the observed C_2_H and c-C_3_H_2_ data toward M8, we aim at obtaining their densities and abundances and to shed some light on their formation mechanism. Using the Atacama Pathfinder Experiment (APEX) 12m, and the Institut de Radioastronomie Millimetrique (IRAM) 30m telescopes, we performed a line survey toward Herschel 36 (Her 36), which is the main ionizing stellar system in M8, and an imaging survey within 1.3x1.3pc around Her 36 of various transitions of C_2_H and C_3_H_2_. We used both Local Thermodynamic Equilibrium (LTE) and non-LTE methods to determine the physical conditions of the emitting gas along with the column densities and abundances of the observed species, which we compared with (updated) gas phase photochemical PDR models. In order to examine the role of polycyclic aromatic hydrocarbons (PAHs) in the formation of small hydrocarbons and to investigate their association with the Hii region, the PDR and the molecular cloud, we compared archival Galactic Legacy Infrared Mid-Plane Survey Extraordinaire (GLIMPSE) 8{mu}m and the Spectral and Photometric Imaging Receiver (SPIRE) 250{mu}m continuum images with the C_2_H emission maps. We observed a total of three rotational transitions of C_2_H with their hyperfine structure components and four rotational transitions of C_3_H_2_ with ortho and para symmetries toward the HII region and the PDR of M8. Fragmentation of PAHs seems less likely to contribute to the formation of small hydrocarbons as the 8 m emission does not follow the distribution of C_2_H emission, which is more associated with the molecular cloud toward the north-west of Her 36. From the quantitative analysis, we obtained abundances of 10^-8 ^and 10^-9^ for C_2_H and c-C_3_H_2_ respectively, and volume densities of the hydrocarbon emitting gas in the range n(H_2_)~5x10^4^-5x10^6^cm^-3^. The observed column densities of C_2_H and c-C_3_H_2_ are reproduced reasonably well by our PDR models. This supports the idea that in high-UV flux PDRs, gas phase chemistry is sufficient to explain hydrocarbon abundances.
- ID:
- ivo://CDS.VizieR/J/MNRAS/508/1084
- Title:
- MaNGA star-forming galaxies
- Short Name:
- J/MNRAS/508/1084
- Date:
- 19 Jan 2022 00:58:55
- Publisher:
- CDS
- Description:
- We investigate radiation hardness within a representative sample of 67 nearby (0.02<~z<~0.06) star-forming (SF) galaxies using the integral field spectroscopic data from the MaNGA survey. The softness parameter {eta}=(O^+^/O^2+^)/(S^+^/S^2+^) is sensitive to the spectral energy distribution of the ionizing radiation. We study {eta} via the observable quantity {eta}'(=([OII]/[OIII])/([SII][SIII])). We analyze the relation between radiation hardness (traced by {eta} and {eta}') and diagnostics sensitive to gas-phase metallicity, electron temperature, density, ionization parameter, effective temperature, and age of ionizing populations. It is evident that low metallicity is accompanied by low log{eta}', i.e. hard radiation field. No direct relation is found between radiation hardness and other nebular parameters though such relations cannot be ruled out. We provide empirical relations between log{eta} and strong emission line ratios N2, O3N2, and Ar3O3, which will allow future studies of radiation hardness in SF galaxies where weak auroral lines are undetected. We compare the variation of [OIII]/[OII] and [SIII]/[SII] for MaNGA data with SF galaxies and HII regions within spiral galaxies from literature and find that the similarity and differences between different data set are mainly due to the metallicity. We find that predictions from photoionization models considering young and evolved stellar populations as ionizing sources in good agreement with the MaNGA data. This comparison also suggests that hard radiation fields from hot and old low-mass stars within or around SF regions might significantly contribute to the observed {eta} values.
- ID:
- ivo://CDS.VizieR/J/A+A/417/615
- Title:
- Maser and outflows in UC HII region
- Short Name:
- J/A+A/417/615
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the results of a single-dish survey of molecular outflows towards a homogeneous sample of 136 ultracompact HII regions for which we had previously obtained observations in the methanol 6.7GHz and water 22.2GHz maser lines. The line profiles of the ^13^CO J=1-0 and 2-1 transitions have been compared to those of the corresponding lines of the C^18^O isotopomer to reveal the occurrence of line wings and hence of molecular outflows.
- ID:
- ivo://CDS.VizieR/J/MNRAS/453/645
- Title:
- Massive molecular outflows distance-limited sample
- Short Name:
- J/MNRAS/453/645
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have observed 99 mid-infrared-bright, massive young stellar objects and compact HII regions drawn from the Red MSX source survey in the J=3-2 transition of ^12^CO and ^13^CO, using the James Clerk Maxwell Telescope. 89 targets are within 6kpc of the Sun, covering a representative range of luminosities and core masses. These constitute a relatively unbiased sample of bipolar molecular outflows associated with massive star formation. Of these, 59, 17 and 13 sources (66, 19 and 15 percent) are found to have outflows, show some evidence of outflow, and have no evidence of outflow, respectively. The time-dependent parameters of the high-velocity molecular flows are calculated using a spatially variable dynamic time-scale. The canonical correlations between the outflow parameters and source luminosity are recovered and shown to scale with those of low-mass sources. For coeval star formation, we find the scaling is consistent with all the protostars in an embedded cluster providing the outflow force, with massive stars up to ~30M_{sun}_ generating outflows. Taken at face value, the results support the model of a scaled-up version of the accretion-related outflow-generation mechanism associated with discs and jets in low-mass objects with time-averaged accretion rates of ~ 10^-3^M_{sun}_/yr on to the cores. However, we also suggest an alternative model, in which the molecular outflow dynamics are dominated by the entrained mass and are unrelated to the details of the acceleration mechanism. We find no evidence that outflows contribute significantly to the turbulent kinetic energy of the surrounding dense cores.
- ID:
- ivo://CDS.VizieR/J/MNRAS/487/1057
- Title:
- Massive SFR beyond the solar circle
- Short Name:
- J/MNRAS/487/1057
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have compiled the most complete compact and ultracompact HII region catalogue to date via multi-wavelength inspection of survey data. We utilise data from the recently available SASSy 850um survey to identify massive star forming clumps in the outer Galaxy (R_GC_>8.5kpc) and cross-match with infrared and radio data of known UC HII regions from the RMS database. For the inner Galaxy sample (R_GC_<8.5kpc), we adopt the compact HII regions from previous works that used similar methods to cross match ATLASGAL with either CORNISH or RMS, depending on the location within the Galactic plane. We present a new UC HII region catalogue that more than doubles the original sample size of previous work, totalling 536 embedded HII regions and 445 host clumps. We examine the distance independent values of N_Ly_/M and L_bol_/M as proxies for massive star formation efficiency and overall star formation efficiency, respectively. We find a significant trend showing that L_bol_/M decreases with increasing RGC, suggesting that the overall star formation per unit mass is less in the outer Galaxy.
- ID:
- ivo://CDS.VizieR/J/ApJ/834/122
- Title:
- Massive star formation in the LMC. I. N159 & N160
- Short Name:
- J/ApJ/834/122
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present images and spectral energy distributions (SEDs) of massive young stellar objects (YSOs) in three star-forming H II regions of the Large Magellanic Cloud: N159A, N159 Papillon, and N160. We use photometry from SOFIA/FORCAST at 25.3-37.1{mu}m to constrain model fits to the SEDs and determine luminosities, ages, and dust content of the embedded YSOs and their local environments. By placing these sources on mid-infrared color-magnitude and color-color diagrams, we analyze their dust properties and consider their evolutionary status. Since each object in the FORCAST images has an obvious bright near-infrared counterpart in Spitzer Space Telescope images, we do not find any evidence for new, very cool, previously undiscovered Class 0 YSOs. Additionally, based on its mid-infrared colors and model parameters, N159A is younger than N160 and the Papillon. The nature of the first extragalactic protostars in N159, P1, and P2, is also discussed.
- ID:
- ivo://CDS.VizieR/J/ApJ/719/1104
- Title:
- Massive star forming complexes in GLIMPSE
- Short Name:
- J/ApJ/719/1104
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We examine the 13 most luminous sources in the WMAP free-free map using the Spitzer GLIMPSE and Midcourse Space Experiment surveys to identify massive star formation complexes, emitting one-third of the Galactic free-free luminosity. We identify star-forming complexes (SFCs) by a combination of bubble morphology in 8um emission and radio recombination line radial velocities. We find 40 SFCs associated with our WMAP sources and determine unique distances up to 31. We interpret the bubbles as evidence for radial expansion. The radial velocity distribution for each source allows us to measure the intrinsic speed of a complex's expansion. This speed is consistent with the size and age of the bubbles. The high free-free luminosities, combined with negligible synchrotron emission, demonstrate that the bubbles are not driven by supernovae. The kinetic energy of the largest bubbles is a substantial fraction of that measured in the older superbubbles found by Heiles. We find that the energy injected into the interstellar medium by our bubbles is similar to that required to maintain turbulent motion in the gas disk inside 8kpc. We report a number of new SFCs powered by massive (M_*_>10^4^M_{sun}_) star clusters. We measure the scale height of the Galactic O stars to be h_*_=35+/-5pc. We determine an empirical relationship between the 8um and free-free emission of the form F_8um_{propto}F^2^_ff_. Finally, we find that the bubble geometry is more consistent with a spherical shell rather than a flattened disk.
