scholarly journals First hot corino detected around an isolated intermediate-mass protostar: Cep E-mm

2018 ◽  
Vol 618 ◽  
pp. A145 ◽  
Author(s):  
J. Ospina-Zamudio ◽  
B. Lefloch ◽  
C. Ceccarelli ◽  
C. Kahane ◽  
C. Favre ◽  
...  
Keyword(s):  
High Velocity ◽  
Rotational Temperature ◽  
Chemical Diversity ◽  
High Mass ◽  
Continuum Emission ◽  
Spectral Signature ◽  
Broad Line ◽  
Intermediate Mass ◽  
Spectral Bands ◽  
Molecular Abundances

Context. Intermediate-mass (IM) protostars provide a bridge between the low- and high-mass protostars. Despite their relevance, little is known about their chemical diversity. Aims. We want to investigate the molecular richness towards the envelope of I-M protostars and to compare their properties with those of low- and high-mass sources. Methods. We have selected the isolated IM Class 0 protostar Cep E-mm to carry out an unbiased molecular survey with the IRAM 30 m telescope between 72 and 350 GHz with an angular resolution lying in the range 7–34″. Our goal is to obtain a census of the chemical content of the protostellar envelope. These data were complemented with NOEMA observations of the spectral bands 85.9–89.6 GHz and 216.8–220.4 GHz at angular resolutions of 2.3″ and 1.4″, respectively. Results. The 30 m spectra show bright emission of O- and N-bearing complex organic molecules (COMs): CH3OH and its rare isotopologues CH2DOH and 13CH3OH, CH3CHO, CH3OCH3, CH3COCH3, HCOOH, HCOOCH3, H2CCO, NH2CHO, CH3CN, C2H3CN, C2H5CN, HNCO and H2CO. We identify up to three components in the spectral signature of COMs: an extremely broad line (eBL) component associated with the outflowing gas (FWHM > 7kms−1), a narrow line (NL) component (FWHM < 3kms−1) associated with the cold envelope, and a broad line (BL) component (FWHM ≃ 5.5kms−1) which traces the signature of a hot corino. The eBL and NL components are detected only in molecular transitions of low excitation and dominate the emission of CH3OH. The BL component is detected in highly excited gas (Eup > 100 K). The NOEMA observations reveal Cep E-mm as a binary protostellar system, whose components, Cep E-A and Cep E-B, are separated by ≈1.7″. Cep E-A dominates the core continuum emission and powers the long-studied, well-known, high-velocity jet associated with HH377. The lower flux source Cep E-B powers another high-velocity molecular jet, reaching velocities of ≈80 km s−1, which propagates in a direction close to perpendicular with respect to the Cep E-A jet. Our interferometric maps show that the emission of COMs arises from a region of ≈0.7″ size around Cep E-A, and corresponds to the BL component detected with the IRAM 30 m telescope. On the contrary, no COM emission is detected towards Cep E-B. We have determined the rotational temperature (Trot) and the molecular gas column densities from a simple population diagram analysis or assuming a given excitation temperature. Rotational temperatures of COMs emission were found to lie in the range 20−40 K with column densities ranging from a few times 1015 cm−2 for O-bearing species, down to a few times 1014 cm−2 for N-bearing species. Molecular abundances are similar to those measured towards other low- and intermediate-mass protostars. Ketene (H2CCO) appears as an exception, as it is found significantly more abundant towards Cep E-A. High-mass hot cores are significantly less abundant in methanol and N-bearing species are more abundant by two to three orders of magnitude. Conclusions. Cep E-mm reveals itself as a binary protostellar system with a strong chemical differentiation between both cores. Only the brightest component of the binary is associated with a hot corino. Its properties are similar to those of low-mass hot corinos.

scholarly journals 3D velocity fields from methanol and water masers in an intermediate-mass protostar

2012 ◽  
Vol 8 (S287) ◽  
pp. 401-406
Author(s):  
C. Goddi ◽  
L. Moscadelli ◽  
A. Sanna
Keyword(s):  
Spatial Scales ◽  
Volume Density ◽  
Radio Continuum ◽  
High Mass ◽  
Continuum Emission ◽  
High Angular Resolution ◽  
Mass Star ◽  
Intermediate Mass ◽  
Molecular Outflow ◽  
Water Masers

AbstractWe report multi-epoch VLBI observations of molecular masers towards the high-mass star forming region AFGL 5142, leading to the determination of the 3D velocity field of circumstellar molecular gas at radii <0.″23 (or 400 AU) from the protostar MM–1. Our observations of CH3OH maser emission enabled, for the first time, a direct measurement of infall of a molecular envelope on to an intermediate-mass protostar (radius of 300 AU, velocity of 5 km s−1, and infall rate of 6 × 10−4n8M⊙ yr−1, where n8 is the ambient volume density in units of 108 cm−3). In addition, our measurements of H2O maser (and radio continuum) emission revealed a collimated bipolar molecular outflow (and ionized jet) from MM–1. The evidence of simultaneous accretion and outflow at small spatial scales, makes AFGL 5142 an extremely compelling target for high-angular resolution studies of high-mass star formation.

scholarly journals New detections of (sub)millimeter hydrogen radio recombination lines towards high-mass star-forming clumps

2018 ◽  
Vol 616 ◽  
pp. A107 ◽  
Author(s):  
W.-J. Kim ◽  
J. S. Urquhart ◽  
F. Wyrowski ◽  
K. M. Menten ◽  
T. Csengeri
Keyword(s):  
High Velocity ◽  
Radio Continuum ◽  
High Mass ◽  
Continuum Emission ◽  
Photon Flux ◽  
Mass Star ◽  
Recombination Line ◽  
Lyman Continuum ◽  
Radio Recombination Line ◽  
5 Ghz

Aims. Previous radio recombination line (RRL) observations of dust clumps identified in the APEX Telescope Large Area Survey of the Galaxy (ATLASGAL) have led to the detection of a large number of RRLs in the 3 mm range. Here, we aim to study their excitation with shorter wavelength (sub)millimeter radio recombination line (submm-RRL) observations. Methods. We made observations of submm-RRLs with low principal quantum numbers (n ≤ 30) using the APEX 12 m telescope, toward 104 H II regions associated with massive dust clumps from ATLASGAL. The observations covered the H25α, H28α, and H35β transitions. Toward a small subsample the H26α, H27α, H29α, and H30α lines were observed to avoid contamination by molecular lines at adjacent frequencies. Results. We have detected submm-RRLs (signal-to-noise (S∕N)≥ 3 σ) from compact H II regions embedded within 93 clumps. The submm-RRLs are approximately a factor of two brighter than the mm-RRLs and consistent with optically thin emission in local thermodynamic equilibrium (LTE). The average ratio (0.31) of the measured H35β/H28α fluxes is close to the LTE value of 0.28. No indication of RRL maser emission has been found. The Lyman photon flux, bolometric, and submm-RRL luminosities toward the submm-RRL detected sources present significant correlations. The trends of dust temperature and the ratio of bolometric luminosity to clump mass, Lbol ∕Mclump, indicate that the H II regions are related to the most massive and luminous clumps. By estimating the production rate of ionizing photons, Q, from the submm-RRL flux, we find that the Q(H28α) measurements provide estimates of the Lyman continuum photon flux consistent with those determined from 5 GHz radio continuum emission. Six RRL sources show line profiles that are a combination of a narrow and a broad Gaussian feature. The broad features are likely associated with high-velocity ionized flows. Conclusions. We have detected submm-RRLs toward 93 ATLASGAL clumps. Six RRL sources have high-velocity RRL components likely driven by high-velocity ionized flows. Their observed properties are consistent with thermal emission that correlates well with the Lyman continuum flux of the H II regions. The sample of H II regions with mm/submm-RRL detections probes, in our Galaxy, luminous clumps (Lbol > 104 L⊙) with high Lbol∕Mclump. We also provide suitable candidates for further studies of the morphology and kinematics of embedded, compact H II regions with the Atacama Large Millimeter/submillimeter Array (ALMA).

scholarly journals Principal component analysis tomography in near-infrared integral field spectroscopy of young stellar objects – I. Revisiting the high-mass protostar W33A

2021 ◽  
Vol 503 (1) ◽  
pp. 270-291
Author(s):  
F Navarete ◽  
A Damineli ◽  
J E Steiner ◽  
R D Blum
Keyword(s):  
Large Scale ◽  
Near Infrared ◽  
Rotation Axis ◽  
Principal Component ◽  
Young Stellar Objects ◽  
High Mass ◽  
Continuum Emission ◽  
Rotating Disc ◽  
Stellar Objects ◽  
K Band

ABSTRACT W33A is a well-known example of a high-mass young stellar object showing evidence of a circumstellar disc. We revisited the K-band NIFS/Gemini North observations of the W33A protostar using principal components analysis tomography and additional post-processing routines. Our results indicate the presence of a compact rotating disc based on the kinematics of the CO absorption features. The position–velocity diagram shows that the disc exhibits a rotation curve with velocities that rapidly decrease for radii larger than 0.1 arcsec (∼250 au) from the central source, suggesting a structure about four times more compact than previously reported. We derived a dynamical mass of 10.0$^{+4.1}_{-2.2}$ $\rm {M}_\odot$ for the ‘disc + protostar’ system, about ∼33 per cent smaller than previously reported, but still compatible with high-mass protostar status. A relatively compact H2 wind was identified at the base of the large-scale outflow of W33A, with a mean visual extinction of ∼63 mag. By taking advantage of supplementary near-infrared maps, we identified at least two other point-like objects driving extended structures in the vicinity of W33A, suggesting that multiple active protostars are located within the cloud. The closest object (Source B) was also identified in the NIFS field of view as a faint point-like object at a projected distance of ∼7000 au from W33A, powering extended K-band continuum emission detected in the same field. Another source (Source C) is driving a bipolar $\rm {H}_2$ jet aligned perpendicular to the rotation axis of W33A.

scholarly journals Hunting for intermediate-mass black holes in globular clusters: an astrometric study of NGC 6441

2021 ◽  
Vol 503 (1) ◽  
pp. 1490-1506
Author(s):  
Maximilian Häberle ◽  
Mattia Libralato ◽  
Andrea Bellini ◽  
Laura L Watkins ◽  
Jörg-Uwe Pott ◽  
...  
Keyword(s):  
Globular Clusters ◽  
Velocity Dispersion ◽  
Angular Resolution ◽  
Hubble Space Telescope ◽  
High Mass ◽  
High Angular Resolution ◽  
Stellar Kinematics ◽  
Intermediate Mass ◽  
The Core ◽  
Large Telescopes

ABSTRACT We present an astrometric study of the proper motions (PMs) in the core of the globular cluster NGC 6441. The core of this cluster has a high density and observations with current instrumentation are very challenging. We combine ground-based, high-angular-resolution NACO@VLT images with Hubble Space Telescope ACS/HRC data and measure PMs with a temporal baseline of 15 yr for about 1400 stars in the centremost 15 arcsec of the cluster. We reach a PM precision of ∼30 µas yr−1 for bright, well-measured stars. Our results for the velocity dispersion are in good agreement with other studies and extend already existing analyses of the stellar kinematics of NGC 6441 to its centremost region never probed before. In the innermost arcsecond of the cluster, we measure a velocity dispersion of (19.1 ± 2.0) km s−1 for evolved stars. Because of its high mass, NGC 6441 is a promising candidate for harbouring an intermediate-mass black hole (IMBH). We combine our measurements with additional data from the literature and compute dynamical models of the cluster. We find an upper limit of $M_{\rm IMBH} \lt 1.32 \times 10^4\, \textrm{M}_\odot$ but we can neither confirm nor rule out its presence. We also refine the dynamical distance of the cluster to $12.74^{+0.16}_{-0.15}$ kpc. Although the hunt for an IMBH in NGC 6441 is not yet concluded, our results show how future observations with extremely large telescopes will benefit from the long temporal baseline offered by existing high-angular-resolution data.

scholarly journals Water maser and radio continuum emission towards IRAS 23139+5939

2007 ◽  
Vol 3 (S242) ◽  
pp. 180-181
Author(s):  
M. A. Trinidad ◽  
S. Curiel ◽  
J. M. Torrelles ◽  
L. F. Rodríguez ◽  
V. Migenes ◽  
...  
Keyword(s):  
Flux Density ◽  
Line Emission ◽  
The Other ◽  
Radio Continuum ◽  
High Mass ◽  
Continuum Emission ◽  
Maser Line ◽  
Water Masers ◽  
Water Maser ◽  
The Continuum

AbstractWe present simultaneous observations of continuum (3.5 and 1.3cm) and water maser line emission (1.3cm) carried out with the VLA-A toward the high-mass object IRAS 23139+5939. We detected two radio continuum sources at 3.5cm separated by 0”5 (~2400 AU), I23139 and I23139S. Based on the observed continuum flux density and the spectral index, we suggest that I23139 is a thermal radio jet associated with a high-mass YSO. On the other hand, based on the spatio-kinematical distribution of the water masers, together with the continuum emission information, we speculate that I23139S is also a jet source powering some of the masers detected in the region.

scholarly journals APEX CO (9-8) MAPPING OF AN EXTREMELY HIGH VELOCITY AND JET-LIKE OUTFLOW IN A HIGH-MASS STAR-FORMING REGION

2011 ◽  
Vol 743 (1) ◽  
pp. L25 ◽  
Author(s):  
Keping Qiu ◽  
Friedrich Wyrowski ◽  
Karl M. Menten ◽  
Rolf Güsten ◽  
Silvia Leurini ◽  
...  
Keyword(s):  
High Velocity ◽  
High Mass ◽  
Mass Star ◽  
Star Forming

scholarly journals ATLASGAL – Ammonia observations towards the southern Galactic plane

2018 ◽  
Vol 609 ◽  
pp. A125 ◽  
Author(s):  
M. Wienen ◽  
F. Wyrowski ◽  
K. M. Menten ◽  
J. S. Urquhart ◽  
C. M. Walmsley ◽  
...  
Keyword(s):  
Standard Deviation ◽  
Hyperfine Structure ◽  
Optical Depth ◽  
Line Width ◽  
Rotational Temperature ◽  
High Mass ◽  
Mass Star ◽  
Star Forming ◽  
Star Forming Regions ◽  
Low Mass

Context. The initial conditions of molecular clumps in which high-mass stars form are poorly understood. In particular, a more detailed study of the earliest evolutionary phases is needed. The APEX Telescope Large Area Survey of the whole inner Galactic disk at 870 μm, ATLASGAL, has therefore been conducted to discover high-mass star-forming regions at different evolutionary phases. Aims. We derive properties such as velocities, rotational temperatures, column densities, and abundances of a large sample of southern ATLASGAL clumps in the fourth quadrant. Methods. Using the Parkes telescope, we observed the NH3 (1, 1) to (3, 3) inversion transitions towards 354 dust clumps detected by ATLASGAL within a Galactic longitude range between 300° and 359° and a latitude within ± 1.5°. For a subsample of 289 sources, the N2H+ (1–0) line was measured with the Mopra telescope. Results. We measured a median NH3 (1, 1) line width of ~ 2 km s-1, rotational temperatures from 12 to 28 K with a mean of 18 K, and source-averaged NH3 abundances from 1.6 × 10-6 to 10-8. For a subsample with detected NH3 (2, 2) hyperfine components, we found that the commonly used method to compute the (2, 2) optical depth from the (1, 1) optical depth and the (2, 2) to (1, 1) main beam brightness temperature ratio leads to an underestimation of the rotational temperature and column density. A larger median virial parameter of ~ 1 is determined using the broader N2H+ line width than is estimated from the NH3 line width of ~ 0.5 with a general trend of a decreasing virial parameter with increasing gas mass. We obtain a rising NH3 (1, 1)/N2H+ line-width ratio with increasing rotational temperature. Conclusions. A comparison of NH3 line parameters of ATLASGAL clumps to cores in nearby molecular clouds reveals smaller velocity dispersions in low-mass than high-mass star-forming regions and a warmer surrounding of ATLASGAL clumps than the surrounding of low-mass cores. The NH3 (1, 1) inversion transition of 49% of the sources shows hyperfine structure anomalies. The intensity ratio of the outer hyperfine structure lines with a median of 1.27 ± 0.03 and a standard deviation of 0.45 is significantly higher than 1, while the intensity ratios of the inner satellites with a median of 0.9 ± 0.02 and standard deviation of 0.3 and the sum of the inner and outer hyperfine components with a median of 1.06 ± 0.02 and standard deviation of 0.37 are closer to 1.

scholarly journals Mapping the 13CO/C18O abundance ratio in the massive star-forming region G29.96−0.02

2018 ◽  
Vol 617 ◽  
pp. A14 ◽  
Author(s):  
S. Paron ◽  
M. B. Areal ◽  
M. E. Ortega
Keyword(s):  
Molecular Clouds ◽  
Abundance Ratio ◽  
High Mass ◽  
Local Thermal Equilibrium ◽  
Mass Star ◽  
Galactocentric Distance ◽  
Star Forming ◽  
Physical Conditions ◽  
The Galaxy ◽  
Molecular Abundances

Aims. Estimating molecular abundances ratios from directly measuring the emission of the molecules toward a variety of interstellar environments is indeed very useful to advance our understanding of the chemical evolution of the Galaxy, and hence of the physical processes related to the chemistry. It is necessary to increase the sample of molecular clouds, located at different distances, in which the behavior of molecular abundance ratios, such as the 13CO/C18O ratio, is studied in detail. Methods. We selected the well-studied high-mass star-forming region G29.96−0.02, located at a distance of about 6.2 kpc, which is an ideal laboratory to perform this type of study. To study the 13CO/C18O abundance ratio (X13∕18) toward this region, we used 12CO J = 3–2 data obtained from the CO High-Resolution Survey, 13CO and C18O J = 3–2 data from the 13CO/C18O (J = 3–2) Heterodyne Inner Milky Way Plane Survey, and 13CO and C18O J = 2–1 data retrieved from the CDS database that were observed with the IRAM 30 m telescope. The distribution of column densities and X13∕18 throughout the extension of the analyzed molecular cloud was studied based on local thermal equilibrium (LTE) and non-LTE methods. Results. Values of X13∕18 between 1.5 and 10.5, with an average of about 5, were found throughout the studied region, showing that in addition to the dependency of X13∕18 and the galactocentric distance, the local physical conditions may strongly affect this abundance ratio. We found that correlating the X13∕18 map with the location of the ionized gas and dark clouds allows us to suggest in which regions the far-UV radiation stalls in dense gaseous components, and in which regions it escapes and selectively photodissociates the C18O isotope. The non-LTE analysis shows that the molecular gas has very different physical conditions, not only spatially throughout the cloud, but also along the line of sight. This type of study may represent a tool for indirectly estimating (from molecular line observations) the degree of photodissociation in molecular clouds, which is indeed useful to study the chemistry in the interstellar medium.

scholarly journals The potential of using KMOS for multi-object massive star spectroscopy

2016 ◽  
Vol 12 (S329) ◽  
pp. 454-454
Author(s):  
Michael Wegner ◽  
Ralf Bender ◽  
Ray Sharples ◽  
Keyword(s):  
Galaxy Formation ◽  
Near Infrared ◽  
High Redshift ◽  
High Mass ◽  
Galactic Centre ◽  
Star Forming ◽  
Star Forming Regions ◽  
Spectral Bands ◽  
Galaxy Formation And Evolution ◽  
Potential Applications

AbstractKMOS, the “K-Band Multi-Object Spectrometer”, was built by a British-German consortium as a second generation instrument for the ESO Paranal Observatory. It is available to the user community since its successful commissioning in 2013 (Sharples et al. 2013). As a multi-object integral field spectrometer for the near infrared, KMOS offers 24 deployable IFUs of 2.8x2.8 arcsec and 14x14 spatial pixels each, which can either be placed individually within a 7.2 arcmin field of view or combined in a Mosaic mode in order to map contiguous fields on sky. The instrument covers the whole range of NIR atmospheric windows (0.8. . .2.5μm) with 5 spectral bands and a resolution of R ≈ 3000. . .4000.Although the main science driver for KMOS was to enable the study of galaxy formation and evolution through multiplexed observations of high-redshift galaxies, KMOS also already exhibited its tremendous potential for the spectroscopy of massive stars: A quantitative study of 27 RSGs in NGC 300 (Gazak et al. 2015) proves its applicability for the spectroscopy of individual stars even beyond the Local Group. A Mosaic observation of the Galactic centre (Feldmeier-Krause et al. 2015) demonstrates how spectra of early-type stars can be extracted from a contiguous field. Other applications include (but need not be limited to) velocity determinations of globular cluster stars, observations of jets/outflows of high mass protostars, or contiguous mapping of star-forming regions.We therefore aim at presenting the excellent capabilities of KMOS to a wider community and indicate potential applications.

Sign in / Sign up

Export Citation Format

Share Document