- ID:
- ivo://CDS.VizieR/J/A+A/565/A30
- Title:
- NGC 3503 YSO candidates
- Short Name:
- J/A+A/565/A30
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present here a follow-up study of the molecular gas and dust in the environs of the star forming region NGC 3503. This study aims at dealing with the interaction of the HII region NGC 3503 with its parental molecular cloud, and also with the star formation in the region, that was possibly triggered by the expansion of the ionization front against the parental cloud. To analyze the molecular gas we use CO(J=2-->1), ^13^CO(J=2-->1), C^18^O(J=2-->1), and HCN(J=3-->2) line data obtained with the on-the-fly technique from the APEX telescope. To study the distribution of the dust, we make use of unpublished images at 870um from the ATLASGAL survey and IRAC-GLIMPSE archival images. We use public 2MASS and WISE data to search for infrared candidate young stellar objects (YSOs) in the region.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/806/74
- Title:
- NH3 line profiles in star-forming regions
- Short Name:
- J/ApJ/806/74
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Anomalous ammonia (NH_3_) spectra, exhibiting asymmetric hyperfine satellite intensity profiles in the (J,K)=(1,1) inversion transition, have been observed in star-forming regions for over 35 years. We present a systematic study of this "hyperfine intensity anomaly" (HIA) toward a sample of 334 high-mass star forming regions: 310 high-mass (>~100M_{sun}_) clumps and 24 infrared dark clouds. The HIA is ubiquitous in high-mass star forming regions. Although LTE excitation predicts that the intensity ratios of the outer satellites and inner satellites are exactly unity, for this sample the ensemble average ratios are 0.812+/-0.004 and 1.125+/-0.005, respectively. We have quantified the HIA and find no significant relationships between the HIA and temperature, line width, optical depth, and the stage of stellar evolution. The fact that HIAs are common in high-mass star-forming regions suggests that the conditions that lead to HIAs are ubiquitous in these regions. A possible link between HIAs and the predictions of the competitive accretion model of high-mass star formation is suggested; however, the expected trends of HIA strength with clump evolutionary stage, rotational temperature, and line width for evolving cores in competitive accretion models are not found. Thus, the exact gas structures that produce HIAs remain unknown. Turbulent gas structures are a possible explanation, but the details need to be explored.
- ID:
- ivo://CDS.VizieR/J/A+A/489/229
- Title:
- NIR photometry of IRAS 19410+2336
- Short Name:
- J/A+A/489/229
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- IRAS 19410+2336 is a young massive star forming region with an intense outflow activity. Outflows are frequently studied in the near-infrared (NIR) since the H_2_ emission in this wavelength range often traces the shocked molecular gas. However, the mechanisms behind the H_2_ emission detected in IRAS 19410+2336 have not been clarified yet. We present here spatially resolved NIR spectroscopy which allows us to verify whether the H_2_ emission originates from thermal emission in shock fronts or from fluorescence excitation by non-ionizing UV photons. Moreover, NIR spectroscopy also offers the possibility of studying the characteristics of the putative driving source(s) of the H_2_ emission by the detection of photospheric and circumstellar spectral features, and of the environmental conditions (e.g. extinction). We obtained long-slit, intermediate-resolution, NIR spectra of IRAS 19410+2336 using LIRIS, the NIR imager/spectrographer mounted on the 4.2m William Herschel Telescope. As a complement, we also obtained J, H and Ks images with the Las Campanas 2.5m Du Pont Telescope, and archival mid-infrared (MIR) Spitzer-images at 3.6, 4.5, 5.8 and 8.0um.
- ID:
- ivo://CDS.VizieR/J/AJ/143/43
- Title:
- NIR photometry of NGC 604 star-forming region
- Short Name:
- J/AJ/143/43
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a near-infrared study focused on the detection and characterization of the youngest stellar component of the NGC 604 giant star-forming region in the Triangulum galaxy (M 33). By means of color-color diagrams derived from the photometry of JHK_s_ images taken with the Gemini Near Infrared Imaging and Spectrometer (NIRI), we have found 68 candidate massive young stellar objects. The spatial distribution of these sources matches the areas where previous studies suggested that star formation might be taking place, and the high spatial resolution of our deep NIRI imaging allows us to pinpoint the star-forming knots. An analysis of the fraction of objects that show infrared excess suggests that the star formation is still active, supporting the presence of a second generation of stars being born, although the evidence for or against sequential star formation does not seem to be conclusive.
- ID:
- ivo://CDS.VizieR/J/AJ/153/126
- Title:
- NIR polarimetric study in the LMC N159/N160 field
- Short Name:
- J/AJ/153/126
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present near-infrared polarimetric results for the N159/N160 star-forming complex in the Large Magellanic Cloud with SIRPOL, the polarimeter of the Infrared Survey Facility. We separated foreground sources using their visual extinction derived from near-infrared photometric data. The 45 young stellar candidates and 2 high-excitation blobs were matched with our sources, and 12 of them showed high polarization that did not originate from the interstellar dust. We made a polarimetric catalog of 252, 277, and 89 sources at the J, H, and K_s_ bands, respectively. Based on the ratios of the polarization degree between these bands, we verify that the origin of these polarized sources is the dichroic extinction from the interstellar dust aligned by the magnetic field and that the ratios follow a power-law dependence of P_{lambda}_~{lambda}^-0.9^. The linear polarization vectors projected onto the H{alpha} image of the complex turned out to follow the local magnetic field structure. The vector map overlaid on dust and gas emissions shows the close correlation between the magnetic field structure and surrounding interstellar medium. We suggest that the derived magnetic field structure supports the sequential formation scenario of the complex.
- ID:
- ivo://CDS.VizieR/J/A+A/646/A122
- Title:
- NOEMA millimeter reduced data cubes of HerBS-89a
- Short Name:
- J/A+A/646/A122
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Exploiting the sensitivity of the IRAM NOrthern Extended Millimeter Array (NOEMA) and its ability to process large instantaneous bandwidths, we have studied the morphology and other properties of the molecular gas and dust in the starburst galaxy, H-ATLAS J131611.5+281219 (HerBS- 89a), at z=2.95. High angular resolution (0.3") images reveal a partial 1.0" diameter Einstein ring in the dust continuum emission and the molecular emission lines of ^12^CO(9-8) and H_2_O(2_02_-1_11_). Together with lower angular resolution (0.6") images, we report the detection of a series of molecular lines including the three fundamental transitions of the molecular ion OH+, namely (1_1_-0_1_), (1_2_-0_1_) and (1_0_-0_1_), seen in absorption; the molecular ion CH+(1-0) seen in absorption (and tentatively in emission); two transitions of amidogen (NH_2_), namely (2_02_-1_11_) and (2_20_-2_11_) seen in emission; and HCN(1_1_-1_0_) and/or NH(1_2_-0_1_) seen in absorption. The NOEMA data are complemented with Very Large Array data tracing the ^12^CO(1-0) emission line, which provides a measurement of the total mass of molecular gas and an anchor for a CO excitation analysis. In addition, we present Hubble Space Telescope imaging that reveals the foreground lensing galaxy in the near-infrared (1.15um). Together with photometric data from the Gran Telescopio Canarias, we derive a photometric redshift of zphot=0.9^+0.3^_-0.5_ for the foreground lensing galaxy. Modelling the lensing of HerBS-89a, we reconstruct the dust continuum (magnified by a factor {mu}~=5.0) and molecular emission lines (magnified by {mu}~4-5) in the source plane, which probe scales of ~0.1" (or 800pc). The ^12^CO(9-8) and H_2_O(2_02_-1_11_) emission lines have comparable spatial and kinematic distributions; the source-plane reconstructions do not clearly distinguish between a one-component and a two-component scenario, but the latter, which reveals two compact rotating components with sizes of ~=1kpc, that are likely merging, more naturally accounts for the broad line widths observed in HerBS-89a. In the core of HerBS-89a, very dense gas with n_H2_~10^7-9^cm^-3^ is revealed by the NH_2_ emission lines and the possible HCN(1_1_-1_0_) absorption line. HerBS-89a is a powerful star forming galaxy with a molecular gas mass of M_mol_=(2.1+/-0.4)x10^11^M_{sun}_, an infrared luminosity of L_IR_=(4.6+/-0.4)x10^12^L_{sun}_, and a dust mass of M_dust_=(2.6+/-0.2)x10^9^M_{sun}_, yielding a dust-to-gas ratio {delta}_GDR_~=80. We derive a star formation rate SFR=614+/-59M_{sun}_/yr and a depletion timescale {tau}_depl_=(3.4+/-1.0)x10^8^years. The OH+ and CH+ absorption lines, which trace low (~100cm^-3^) density molecular gas, all have their main velocity component red-shifted by {DELTA}V~100km/s relative to the global CO reservoir. We argue that these absorption lines trace a rare example of gas inflow towards the center of a starburst galaxy, indicating that HerBS-89a is accreting gas from its surroundings.
- ID:
- ivo://CDS.VizieR/J/BaltA/18/141
- Title:
- North America/Pelican red clump giants ugriJHK
- Short Name:
- J/BaltA/18/141
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A possibility of applying 2MASS J, H, Ks, IPHAS r, i and Mega-Cam u, g photometry of red giants for determining distances to dark clouds is investigated. Red clump giants with a small admixture of G5-K1 and M2-M3 stars of the giant branch can be isolated and used in determining distances to separate clouds or spiral arms. Interstellar extinctions of background red giants can be also used for mapping dust surface density in the cloud.
- ID:
- ivo://CDS.VizieR/J/ApJ/438/181
- Title:
- Observations of H II Regions in M81
- Short Name:
- J/ApJ/438/181
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Images of the type Sab spiral galaxy M81 were obtained in far-UV and near-UV bands by the Ultraviolet Imaging Telescope (UIT) during the Astro-1 Spacelab mission of 1990 December. Magnitudes in the two UV bands are determined for 52 H II regions from the catalog of Petit, Sivan, & Karachentsev (1988A&AS...74..475P). Fluxes of the H-alpha and H-beta emission lines are determined from CCD images. Extinctions for the brightest H II regions are determined from observed Balmer decrements. Fainter H II regions are assigned the average of published radio-H-alpha extinctions for several bright H II regions. The radiative transfer models of Witt, Thronson, & Capuano (1992, ApJ, 393, 611) are shown to predict a relationship between Balmer Decrement and H-alpha extinction consistent with observed line and radio fluxes for the brightest 7 H II regions and are used to estimate the UV extinction. Ratios of Lyman continuum flux (computed from the extinction corrected H-alpha flux) to the extinction corrected far-UV flux are compared with ratios predicted by model spectra computed for IMF slope equal to -1.0 and stellar masses ranging from 5 to 120 Msun. Ages and masses are estimated by comparing the H-alpha and far-UV fluxes and their ratio with the models. The total of the estimated stellar masses for the 52 H II regions is 1.4x10^5^ Msun. The star-formation rate inferred for M81 from the observed UV and H-alpha fluxes is low for a spiral galaxy at ~0.13 Msun/yr, but consistent with the low star-formation rates obtained by Kennicutt (1983ApJ...272...54K) and Caldwell et al. (1991ApJ...370..526C) for early-type spirals.
- ID:
- ivo://CDS.VizieR/J/A+AS/137/43
- Title:
- OH/H2O masers database
- Short Name:
- J/A+AS/137/43
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Table 3 contains VLA spectra and positions for OH and H2O maser spots in 74 star-forming regions mapped by Forster and Caswell (1989A&A...213..339F). Galactic coordinates are given, followed by offset positions of the 22GHz continuum peak (HII) if detected, and the flux, velocity and positions of OH and H_2_O maser spots mapped in that field.
- ID:
- ivo://CDS.VizieR/J/A+A/414/235
- Title:
- OH maser emission from star forming regions
- Short Name:
- J/A+A/414/235
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- High sensitivity observations of all four transitions of the ground state at 18cm of OH in both senses of circular polarization have been carried out with the Nancay radio telescope. The sample was a set of 100 star forming regions detected in a recent unbiased survey of 6668MHz methanol masers (Szymczak et al., 2002A&A...392..277S). OH maser emission was found in 55 objects of which 31 were not previously catalogued.
