- ID:
- ivo://CDS.VizieR/J/ApJ/867/167
- Title:
- High-mass outflows from the COHRS CO(3-2) survey
- Short Name:
- J/ApJ/867/167
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- An unbiased search of molecular outflows within the region of the CO High Resolution survey has identified 157 high-mass outflows from a sample of 770 APEX Telescope Large Area Survey of the Galaxy clumps with a detection rate of 20%. The detection rate of outflows increases for clumps with higher M_clump_, L_bol_, L_bol_/M_clump_,N_H2_, and T_dust_ compared to the clumps with no outflow. The detection rates of the outflow increase from protostellar (8%) to young stellar object clump (17%) to massive star-forming clump (29%). The detection rate 26% for quiescent clump is preliminary, because the sample of quiescent clumps is small. A statistical relation between the outflow and clump masses for our sample is log(M_out_/M_{sun}_)=(-1.1+/-0.21)+(0.9+/-0.07)log(M_clump_/M_{sun}_). The detection rate of outflows and the outflow mass-loss rate show an increase with increasing M_clump_, L_bol_, N_H_2_, and T_dust_, which indicates that clumps with outflow with higher parameter values are at a more advanced evolutionary stage. The outflow mechanical force increases with increasing bolometric luminosities. No clear evidence has yet been found that higher-mass outflows have different launching conditions than low-mass outflows.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/417/115
- Title:
- High-mass protostellar candidates
- Short Name:
- J/A+A/417/115
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present maps of the 850{mu}m and 450{mu}m continuum emission seen towards a sample of 68 high-mass protostellar candidates with luminosities ranging from 10^2.5^L_{sun}_ to ~10^5^L_{sun}_. Most of these candidate high-mass stars are in the earliest stages of evolution, and have not yet developed an ultra-compact HII region. We observe a variety of continuum emission morphologies, from compact symmetric sources through to multiple cores embedded in long filaments of emission. We find on average there is a 65% probability of an IRAS point-source having a companion detection at submillimetre wavelengths. The ratio of integrated flux to peak flux for our detections shows no strong dependence on distance, suggesting the emission we have observed is primarily from scale-free envelopes with power-law density structures. Assuming a near kinematic distance projection, the clumps we detect vary in mass from ~1M_{sun}_ to over 1000M_{sun}_, with a mean clump mass of 330M_{sun}_, column density of 9x10^23cm^-2^ and diameter of ~0.6pc. The high luminosity and low mass of the smallest clumps suggests they are accompanied by a minimal number of stellar companions, while the most massive clumps may be examples of young protogroups and protoclusters. We measure the spectral index of the dust emission ({alpha}) and the spectral index of the dust grain opacity ({beta}) towards each object, finding clumps with morphologies suggestive of strong temperature gradients, and of grain growth in their dense inner regions. We find a mean value for beta of 0.9, significantly smaller than observed towards ultra-compact HII regions.
- ID:
- ivo://CDS.VizieR/J/A+A/498/147
- Title:
- High mass protostellar objects physical parameters
- Short Name:
- J/A+A/498/147
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In a previous work (Paper I, Kumar & Grave, 2007A&A...472..155K) a sample of 380 HMPO targets was studied using the GLIMPSE point source catalog and images. A colour-magnitude analysis of the point sources resulted in the identification of infrared counterparts (IRC) of the (sub)mm cores of HMPO candidates which were considered bona fide targets. We aim to estimate and analyse the physical properties of the infrared counterparts of HMPOs by comparing their spectral energy distributions (SED) with those predicted by radiative transfer accretion models of YSOs.
- ID:
- ivo://CDS.VizieR/J/A+A/625/A103
- Title:
- 19 highmass SFR Herschel spectra and maps
- Short Name:
- J/A+A/625/A103
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The physical conditions during high-mass star formation are poorly understood. Outflow and infall motions have been detected around massive protostellar objects, but their dependence on mass, luminosity, and age is unclear. In addition, physical conditions and molecular abundances are often estimated using simple assumptions such as spherical shape and chemical homogeneity, which may limit the accuracy of the results. We aim to characterize the dust and gas distribution and kinematics of the envelopes of high-mass protostars. In particular, we search for infall motions, abundance variations, and deviations from spherical symmetry, using Herschel data from the WISH program. We used HIFI maps of the 987GHz H_2_O 2_02_-1_11_ emission to measure the sizes and shapes of 19 high-mass protostellar envelopes. To identify infall, we used HIFI spectra of the optically thin C^18^O 9-8 and H_2_^18^O 1_11_-0_00_ lines. The high-J C^18^O line traces the warm central material and redshifted H_2_^18^O 1_11_-0_00_ absorption indicates material falling onto the warm core. We probe small-scale chemical differentiation by comparing H_2_O 752 and 987GHz spectra with those of H_2_^18^O. Our measured radii of the central part of the H_2_O 2_02_-1_11_ emission are 30-40% larger than the predictions from spherical envelope models, and axis ratios are <2, which we consider good agreement. For 11 of the 19 sources, we find a significant redshift of the H_2_^18^O 1_11_-0_00_ line relative to C^18^O 9-8. The inferred infall velocities are 0.6-3.2km/s, and estimated mass inflow rates range from 7x10^-5^ to 2x10^-2^M_{sun}_/yr. The highest mass inflow rates seem to occur toward the sources with the highest masses, and possibly the youngest ages. The other sources show either expanding motions or H_2_^18^O lines in emission. The H_2_^18^O 1_11_-0_00_ line profiles are remarkably similar to the differences between the H_2_O 2_02_-1_11_ and 2_11_-2_02_ profiles, suggesting that the H_2_^18^O line and the H_2_O 2_02_-1_11_ absorption originate just inside the radius where water evaporates from grains, typically 1000-5000au from the center. In some sources, the H_2_^18^O line is detectable in the outflow, where no C^18^O emission is seen. Together, the H_2_^18^O absorption and C^18^O emission profiles show that the water abundance around high-mass protostars has at least three levels: low in the cool outer envelope, high within the 100K radius, and very high in the outflowing gas. Thus, despite the small regions, the combination of lines presented in this work reveals systematic inflows and chemical information about the outflows.
- ID:
- ivo://CDS.VizieR/J/MNRAS/510/3389
- Title:
- High-mass star formation evolutionary trends
- Short Name:
- J/MNRAS/510/3389
- Date:
- 04 Mar 2022 13:27:21
- Publisher:
- CDS
- Description:
- ATLASGAL is an 870um dust survey of 420deg^2^ the inner Galactic plane and has been used to identify ~10000 dense molecular clumps. Dedicated follow-up observations and complementary surveys are used to characterize the physical properties of these clumps, map their Galactic distribution, and investigate the evolutionary sequence for high-mass star formation. The analysis of the ATLASGAL data is ongoing: We present an up-to-date version of the catalogue. We have classified 5007 clumps into four evolutionary stages (quiescent, protostellar, young stellar objects and HII regions) and find similar numbers of clumps in each stage, suggesting a similar lifetime. The luminosity-to-mass (L_bol_/M_fwhm_) ratio curve shows a smooth distribution with no significant kinks or discontinuities when compared to the mean values for evolutionary stages indicating that the star formation process is continuous and that the observational stages do not represent fundamentally different stages or changes in the physical mechanisms involved. We compare the evolutionary sample with other star formation tracers (methanol and water masers, extended green objects and molecular outflows) and find that the association rates with these increases as a function of evolutionary stage, confirming that our classification is reliable. This also reveals a high association rate between quiescent sources and molecular outflows, revealing that outflows are the earliest indication that star formation has begun and that star formation is already ongoing in many of the clumps that are dark even at 70um.
- ID:
- ivo://CDS.VizieR/J/other/ApSS/361.191
- Title:
- High-mass star forming clumps from MALT90
- Short Name:
- J/other/ApSS/361
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A total of 197 relatively isolated high-mass star-forming clumps were selected from the Millimeter Astronomy Legacy Team 90GHz (MALT90) survey data and their global chemical evolution investigated using four molecular lines, N_2_H^+^(1-0), HCO^+^(1-0), HCN(1-0), and HNC(1-0). The results suggest that the global averaged integrated intensity ratios I(HCO^+^)/I(HNC), I(HCN)/I(HNC), I(N_2_H^+^)/I(HCO^+^), and I(N_2_H^+^)/ I(HCN) are promising tracers for evolution of high-mass star-forming clumps. The global averaged column densities and abundances of N_2_H^+^, HCO^+^, HCN, and HNC increase as clumps evolve. The global averaged abundance ratios X(HCN)/X(HNC) could be used to trace evolution of high-mass star forming clumps, X(HCO^+^)/X(HNC) is more suitable for distinguishing high-mass star-forming clumps in prestellar (stage A) from those in protostellar (stage B) and HII/PDR region (stage C). These results suggest that the global averaged integrated intensity ratios between HCN(1-0), HNC(1-0), HCO^+^(1-0) and N_2_H^+^(1-0) are more suitable for tracing the evolution of high-mass star forming clumps. We also studied the chemical properties of the target high-mass star-forming clumps in each spiral arm of the Galaxy, and got results very different from those above. This is probably due to the relatively small sample in each spiral arm. For high-mass star-forming clumps in Sagittarius arm and Norma-Outer arm, comparing two groups located on one arm with different Galactocentric distances, the clumps near the Galactic Center appear to be younger than those far from the Galactic center, which may be due to more dense gas concentrated near the Galactic Center, and hence more massive stars being formed there.
- ID:
- ivo://CDS.VizieR/J/ApJS/231/11
- Title:
- High-mass starless clump candidates from ATLASGAL
- Short Name:
- J/ApJS/231/11
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report a sample of 463 high-mass starless clump (HMSC) candidates within -60{deg}<l<60{deg} and -1{deg}<b<1{deg}. This sample has been singled out from 10861 ATLASGAL clumps. None of these sources are associated with any known star-forming activities collected in SIMBAD and young stellar objects identified using color-based criteria. We also make sure that the HMSC candidates have neither point sources at 24 and 70{mu}m nor strong extended emission at 24{mu}m. Most of the identified HMSCs are infrared dark, and some are even dark at 70{mu}m. Their distribution shows crowding in Galactic spiral arms and toward the Galactic center and some well-known star-forming complexes. Many HMSCs are associated with large-scale filaments. Some basic parameters were attained from column density and dust temperature maps constructed via fitting far-infrared and submillimeter continuum data to modified blackbodies. The HMSC candidates have sizes, masses, and densities similar to clumps associated with Class II methanol masers and H II regions, suggesting that they will evolve into star-forming clumps. More than 90% of the HMSC candidates have densities above some proposed thresholds for forming high-mass stars. With dust temperatures and luminosity-to-mass ratios significantly lower than that for star-forming sources, the HMSC candidates are externally heated and genuinely at very early stages of high-mass star formation. Twenty sources with equivalent radii r_eq_<0.15pc and mass surface densities {Sigma}>0.08g/cm^2^ could be possible high-mass starless cores. Further investigations toward these HMSCs would undoubtedly shed light on comprehensively understanding the birth of high-mass stars.
- ID:
- ivo://CDS.VizieR/J/ApJ/886/100
- Title:
- High-mass white dwarfs in Gaia DR2
- Short Name:
- J/ApJ/886/100
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Revealed by Gaia DR2, the Q branch is a narrow and prominent branch of white dwarf overdensity on the H-R diagram. We find that there are significantly more fast-moving white dwarfs on the Q branch, which have very old true ages but young photometric ages. This age discrepancy suggests a cooling anomaly in some white dwarfs on the Q branch, posing a challenge to current white dwarf cooling models. We tabulate the information of nearby high-mass white dwarfs (d<250, 1.08<m_WD<1.23), which is used to investigate the Q branch and its physical origin in Cheng et al. (2019). This table contains the WD name, photometry and astrometry from Gaia DR2, H-R diagram coordinates and transverse velocity that we derive, and spectral information from Montreal White Dwarf Database (MWDD).
- ID:
- ivo://CDS.VizieR/J/A+A/442/1135
- Title:
- High-mass X-ray binaries in the Magellanic Clouds
- Short Name:
- J/A+A/442/1135
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalogue of high-mass X-ray binaries in the Magellanic Clouds. The catalogue lists source name(s), coordinates, apparent magnitudes, orbital parameters, and X-ray luminosity of 128 high-mass X-ray binaries, together with stellar parameters of the components, other characteristic properties and a comprehensive selection of the relevant literature. The aim of this catalogue is to provide easy access to the basic information on the X-ray sources and their counterparts in other wavelength ranges (UV, optical, IR, radio). Most of the sources are identified to be Be/X-ray binaries. Some sources, however, are only tentatively identified as high-mass X-ray binaries on the basis of a transient character and/or a hard X-ray spectrum. Further identification in other wavelength bands is needed to finally determine the nature of these sources. In cases where there is some doubt about the high-mass nature of the X-ray binary this is mentioned. Literature published before 1 May 2005 has, as far as possible, been taken into account.
- ID:
- ivo://CDS.VizieR/J/A+A/586/A81
- Title:
- High-mass X-ray binaries in the SMC
- Short Name:
- J/A+A/586/A81
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The last comprehensive catalogue of high-mass X-ray binaries in the Small Magellanic Cloud (SMC) was published about ten years ago. Since then new such systems were discovered, mainly by X-ray observations with Chandra and XMM-Newton. For the majority of the proposed HMXBs in the SMC no X-ray pulsations were discovered as yet, and unless other properties of the X-ray source and/or the optical counterpart confirm their HMXB nature, they remain only candidate HMXBs. From a literature search we collected a catalogue of 148 confirmed and candidate HMXBs in the SMC and investigated their properties to shed light on their real nature. Based on the sample of well-established HMXBs (the pulsars), we investigated which observed properties are most appropriate for a reliable classification. We defined different levels of confidence for a genuine HMXB based on spectral and temporal characteristics of the X-ray sources and colour-magnitude diagrams from the optical to the infrared of their likely counterparts. We also took the uncertainty in the X-ray position into account. We identify 27 objects that probably are misidentified because they lack an infrared excess of the proposed counterpart. They were mainly X-ray sources with a large positional uncertainty. This is supported by additional information obtained from more recent observations. Our catalogue comprises 121 relatively high-confidence HMXBs (the vast majority with Be companion stars). About half of the objects show X-ray pulsations, while for the rest no pulsations are known as yet. A comparison of the two subsamples suggests that long pulse periods in excess of a few 100s are expected for the "non-pulsars", which are most likely undetected because of aperiodic variability on similar timescales and insufficiently long X-ray observations. The highest X-ray variability together with the lowest observed minimum fluxes for short-period pulsars indicate that in addition to the eccentricity of the orbit, its inclination against the plane of the Be star circum-stellar disc plays a major role in determining the outburst behaviour. The large population of HMXBs in the SMC, in particular Be X-ray binaries, provides the largest homogeneous sample of such systems for statistical population studies.