1,721,334 research outputs found
A molecular line survey of the candidate massive Class 0 protostar IRAS 23385+6053
No full textWe have carried out a molecular line survey of the candidate massive
protostar IRAS 23385+605
IRAS 23385+6053: A candidate protostellar massive object
No full textWe present the results of a multi-line and continuum study
towards the source IRAS 23385+6053
performed with the IRAM-30 m telescope, the Plateau de Bure
Interferometer, the Very Large Array Interferometer and the James Clerk
Maxwell Telescope. We have obtained single-dish maps in the C18O (1–0),
C17O (1–0) and (2–1) rotational lines, interferometric maps in the
CH3C2H (13–12) line, NH3(1,1) and (2,2) inversion transitions, and single-pointing observations of the CH3C2H (6–5), (8–7) and (13–12) rotational
lines.
The new results confirm our earlier findings, namely that IRAS 23385+6053 is a good candidate high-mass protostellar object, precursor
of an ultracompact Hi
JOYS: Disentangling the warm and cold material in the high-mass IRAS 23385+6053 cluster
Get PDFContext. High-mass star formation occurs in a clustered mode where fragmentation is observed from an early stage onward. Young protostars can now be studied in great detail with the recently launched James Webb Space Telescope (JWST).
Aims. We study and compare the warm (>100 K) and cold (<100 K) material toward the high-mass star-forming region (HMSFR) IRAS 23385+6053 (IRAS 23385 hereafter) combining high-angular-resolution observations in the mid-infrared (MIR) with the JWST Observations of Young protoStars (JOYS) project and with the NOrthern Extended Millimeter Array (NOEMA) at millimeter (mm) wavelengths at angular resolutions of ≈0.″2–1.″0.
Methods. We investigated the spatial morphology of atomic and molecular species using line-integrated intensity maps. We estimated the temperature and column density of different gas components using H2 transitions (warm and hot component) and a series of CH3CN transitions as well as 3 mm continuum emission (cold component).
Results. Toward the central dense core of IRAS 23385, the material consists of relatively cold gas and dust (≈50 K), while multiple outflows create heated and/or shocked H2 and show enhanced temperatures (≈400 K) along the outflow structures. An energetic outflow with enhanced emission knots of [Fe I
IRAS 23385+6053: An embedded massive cluster in the making
Get PDFContext. This study is part of the project “CORE”, an IRAM/NOEMA large program consisting of observations of the millimeter continuum and molecular line emission towards 20 selected high-mass star forming regions. The goal of the program is to search for circumstellar accretion disks, study the fragmentation process of molecular clumps, and investigate the chemical composition of the gas in these regions.
Aims. We focus on IRAS 23385+6053, which is believed to be the least evolved source of the CORE sample. This object is characterized by a compact molecular clump that is IR dark shortward of 24 µm and is surrounded by a stellar cluster detected in the near-IR. Our aim is to study the structure and velocity field of the clump.
Methods. The observations were performed at ∼1.4 mm and employed three configurations of NOEMA and additional single-dish maps, merged with the interferometric data to recover the extended emission. Our correlator setup covered a number of lines from well-known hot core tracers and a few outflow tracers. The angular (∼0.′′45–0.′′9) and spectral (0.5 km s−1) resolutions were sufficient to resolve the clump in IRAS 23385+6053 and investigate the existence of large-scale motions due to rotation, infall, or expansion.
Results. We find that the clump splits into six distinct cores when observed at sub-arcsecond resolution. These are identified through their 1.4 mm continuum and molecular line emission. We produce maps of the velocity, line width, and rotational temperature from the methanol and methyl cyanide lines, which allow us to investigate the cores and reveal a velocity and temperature gradient in the most massive core. We also find evidence of a bipolar outflow, possibly powered by a low-mass star. Conclusions. We present the tentative detection of a circumstellar self-gravitating disk lying in the most massive core and powering a largescale outflow previously known in the literature. In our scenario, the star powering the flow is responsible for most of the luminosity of IRAS 23385+6053 (∼3000 L⊙). The other cores, albeit with masses below the corresponding virial masses, appear to be accreting material
from their molecular surroundings and are possibly collapsing or on the verge of collapse. We conclude that we are observing a sample of star-forming cores that is bound to turn into a cluster of massive stars
IRAS 23385+6053: An embedded massive cluster in the making
No full textContext. This study is part of the CORE project, an IRAM/NOEMA large program consisting of observations of the millimeter continuum and molecular line emission towards 20 selected high-mass star-forming regions. The goal of the program is to search for circumstellar accretion disks, study the fragmentation process of molecular clumps, and investigate the chemical composition of the gas in these regions. Aims. We focus on IRAS 23385+6053, which is believed to be the least-evolved source of the CORE sample. This object is characterized by a compact molecular clump that is IR-dark shortward of 24 μm and is surrounded by a stellar cluster detected in the near-IR. Our aim is to study the structure and velocity field of the clump. Methods. Observations were performed at ~1.4 mm and employed three configurations of NOEMA and additional single-dish maps, merged with the interferometric data to recover the extended emission. Our correlator setup covered a number of lines from well-known hot core tracers and a few outflow tracers. The angular (~0′′.45-0′′.9) and spectral (0.5 km s-1) resolutions were sufficient to resolve the clump in IRAS 23385+6053 and investigate the existence of large-scale motions due to rotation, infall, or expansion. Results. We find that the clump splits into six distinct cores when observed at sub-arcsecond resolution. These are identified through their 1.4 mm continuum and molecular line emission. We produce maps of the velocity, line width, and rotational temperature from the methanol and methyl cyanide lines, which allow us to investigate the cores and reveal a velocity and temperature gradient in the most massive core. We also find evidence of a bipolar outflow, possibly powered by a low-mass star. Conclusions. We present the tentative detection of a circumstellar self-gravitating disk lying in the most massive core and powering a large-scale outflow previously known in the literature. In our scenario, the star powering the flow is responsible for most of the luminosity of IRAS 23385+6053 (~3000 L⊙ ). The other cores, albeit with masses below the corresponding virial masses, appear to be accreting material from their molecular surroundings and are possibly collapsing or on the verge of collapse. We conclude that we are observing a sample of star-forming cores that is bound to turn into a cluster of massive stars. © ESO 2019.</p
IRAS 23385+6053: A Prototype Massive Class 0 Object
No full textIRAS 23385+6053 is a young stellar object with a luminosity of ~1.6×104 Lsolar at a kinematic distance of 4.9 kpc. This candidate precursor of an ultracompact H II region is associated with a millimeter source detected at the James Clerk Maxwell Telescope but is undetected at centimeter wavelengths with the VLA. We observed this source with the Owens Valley Radio Observatory millimeter array at 3.4 mm in the continuum, HCO+ (1-->0), H13CO+ (1-->0), and SiO (v=0, 2-->1) line emission and with CAM aboard the Infrared Space Observatory at 6.75 and 15 μm. The IRAS source is coincident with a 3.4 mm compact (rcore~=0.048 pc) and massive (M~=370 Msolar) core, which is undetected at 15 μm to a 3 σ level of 6 mJy; this is compatible with the derived H2 column density of ~2×1024 cm-2 and the estimated visual extinction AV~2000 mag. We find Lsubmm/Lbol~3×10-3 and Menv/M*>>1, which is typical of class 0 objects. The source is also associated with a compact outflow characterized by a size <~rcore, a dynamical timescale of <~7×103 yr, and a mass-loss rate Ṁ>~10-3 Msolar yr-1. The axis of the outflow is oriented nearly perpendicular to the plane of the sky, ruling out the possibility that the nondetection at 15 μm is the result of a geometric effect. All these properties suggest that IRAS 23385+6053 is the first example of a bona fide massive class 0 object
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
IRAS 23385+6053: A candidate protostellar massive object
No full textWe present the results of a multi-line and continuum study towards the source IRAS 23385+6053 performed with the IRAM-30 m telescope, the Plateau de Bure Interferometer, the Very Large Array Interferometer and the James Clerk Maxwell Telescope. We have obtained single-dish maps in the C18O (1-0), C17O (1-0) and (2-1) rotational lines, interferometric maps in the CH3C2H (13-12) line, NH3(1,1) and (2,2) inversion transitions, and single-pointing observations of the CH3C2H (6-5), (8-7) and (13-12) rotational lines. The new results confirm our earlier findings, namely that IRAS 23385+6053 is a good candidate high-mass protostellar object, precursor of an ultracompact HII region. The source is roughly composed of two regions: a molecular core ∼0.03 / 0.04 pc in size, with a temperature of ∼40 K and an H2 volume density of the order of 107 cm-3, and an extended halo of diameter ≤0.4 pc, with an average kinetic temperature of ∼15 K and H2 volume density of the order of 105 cm-3. The core temperature is much smaller than what is typically found in molecular cores of the same diameter surrounding massive ZAMS stars. From the continuum spectrum we deduce that the core luminosity is between 150 and 1.6 × 104 L⊙, and we believe that the upper limit is near the ``true'' source luminosity. Moreover, by comparing the H2 volume density obtained at different radii from the IRAS source, we find that the halo has a density profile of the type nH2∝ r-2.3. This suggests that the source is gravitationally unstable. The latter hypothesis is also supported by a low virial-to-gas mass ratio (MVIR/Mgas ≤ 0.3). Finally, we demonstrate that the temperature at the core surface is consistent with a core luminosity of 103 L⊙ and conclude that we might be observing a protostar still accreting material from its parental cloud, the mass of which is at present ∼6 M⊙
Author Correction: Dynamics of RIF1 SUMOylation is regulated by PIAS4 in the maintenance of Genomic Stability (vol 7, 2017)
No full text10.1038/s41598-018-23385-4SCIENTIFIC REPORTS8
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