scholarly journals Spectroscopic characterization of the known O-star population in Cygnus OB2

2020 ◽  
Vol 642 ◽  
pp. A168
Author(s):  
S. R. Berlanas ◽  
A. Herrero ◽  
F. Comerón ◽  
S. Simón-Díaz ◽  
D. J. Lennon ◽  
...  
Keyword(s):  
Binary Systems ◽  
Spectroscopic Analysis ◽  
Spectroscopic Characterization ◽  
Spectroscopic Binaries ◽  
High Mass ◽  
Evolutionary Status ◽  
Stellar Content ◽  
Double Line ◽  
Star Forming

Context. Cygnus OB2 provides a unique insight into the high-mass stellar content in one of the largest groups of young massive stars in our Galaxy. Although several studies of its massive population have been carried out over the last decades, an extensive spectroscopic study of the whole known O-star population in the association is still lacking. Aims. We aim to carry out a spectroscopic characterization of all the currently known O stars in Cygnus OB2, determining the distribution of rotational velocities and accurate stellar parameters to obtain an improved view of the evolutionary status of the region. Methods. Based on existing and new optical spectroscopy, we performed a detailed quantitative spectroscopic analysis of all the known O-type stars identified in the association. For this purpose, we used the user-friendly iacob-broad and iacob-gbat automatized tools, FASTWIND stellar models, and astrometry provided by the Gaia second data release. Results. We created the most complete spectroscopic census of O stars carried out so far in Cygnus OB2 using already existing and new spectroscopy. We present the spectra for 78 O-type stars, from which we identify new binary systems, obtain the distribution of rotational velocities, and determine the main stellar parameters for all the stars in the region that have not been detected as double-line spectroscopic binaries. We also derive radii, luminosities, and masses for those stars with reliable Gaia astrometry, in addition to creating the Hertzsprung-Russell Diagram to interpret the evolutionary status of the association. Finally, we inspect the dynamical state of the population and identify runaway candidates. Conclusions. Our spectroscopic analysis of the O-star population in Cygnus OB2 has led to the discovery of two new binary systems and the determination of the main stellar parameters, including rotational velocities, luminosities, masses, and radii for all identified stars. This work has shown the improvement reached when using accurate spectroscopic parameters and astrometry for the interpretation of the evolutionary status of a population, revealing, in the case of Cygnus OB2, at least two star-forming bursts at ~3 and ~5 Myr. We find an apparent deficit of very fast rotators in the distribution of rotational velocities. The inspection of the dynamical distribution of the sample has allowed us to identify nine O stars with peculiar proper motions and discuss a possible dynamical ejection scenario or past supernova explosions in the region.

scholarly journals Massive Stars in the Tarantula Nebula: A Rosetta Stone for Extragalactic Supergiant HII Regions

Galaxies ◽  
2019 ◽  
Vol 7 (4) ◽  
pp. 88 ◽  
Author(s):  
Paul A. Crowther
Keyword(s):  
Massive Stars ◽  
Hii Regions ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
High Mass ◽  
Stellar Content ◽  
X Ray ◽  
Star Forming ◽  
Rosetta Stone ◽  
The Individual

A review of the properties of the Tarantula Nebula (30 Doradus) in the Large Magellanic Cloud is presented, primarily from the perspective of its massive star content. The proximity of the Tarantula and its accessibility to X-ray through radio observations permit it to serve as a Rosetta Stone amongst extragalactic supergiant HII regions since one can consider both its integrated characteristics and the individual properties of individual massive stars. Recent surveys of its high mass stellar content, notably the VLT FLAMES Tarantula Survey (VFTS), are reviewed, together with VLT/MUSE observations of the central ionizing region NGC 2070 and HST/STIS spectroscopy of the young dense cluster R136, provide a near complete Hertzsprung-Russell diagram of the region, and cumulative ionizing output. Several high mass binaries are highlighted, some of which have been identified from a recent X-ray survey. Brief comparisons with the stellar content of giant HII regions in the Milky Way (NGC 3372) and Small Magellanic Cloud (NGC 346) are also made, together with Green Pea galaxies and star forming knots in high-z galaxies. Finally, the prospect of studying massive stars in metal poor galaxies is evaluated.

scholarly journals Barium and related stars, and their white-dwarf companions

2019 ◽  
Vol 626 ◽  
pp. A127 ◽  
Author(s):  
A. Jorissen ◽  
H. M. J. Boffin ◽  
D. Karinkuzhi ◽  
S. Van Eck ◽  
A. Escorza ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Mass Distribution ◽  
White Dwarf ◽  
Binary Systems ◽  
Asymptotic Giant Branch ◽  
Spectroscopic Binaries ◽  
High Mass ◽  
Initial Mass ◽  
Mass Ratio ◽  
Orbital Elements

Context. Barium and S stars without technetium are red giants and are suspected of being members of binary systems due to their overabundances in heavy elements. These elements are produced by the s-process of nucleosynthesis, despite the stars not being evolved enough to be able to activate the s-process in their interiors. A companion formerly on the asymptotic giant branch (now a white dwarf) is supposed to be responsible for the barium- and S-star enrichment in s-process elements through mass transfer. Aims. This paper provides both long-period and revised orbits for barium and S stars, adding to previously published orbits. The sample of barium stars with strong anomalies (i.e., those classified as Ba3, Ba4, or Ba5 in the Warner scale) comprises all known stars of that kind, and in that sense forms a complete sample that allows us to investigate several orbital properties of these post-mass-transfer binaries in an unbiased way. Methods. Orbital elements are derived from radial velocities collected from a long-term radial-velocity monitoring campaign performed with the HERMES spectrograph mounted on the Mercator 1.2 m telescope. These new measurements were combined with older, CORAVEL measurements. With the aim of investigating possible correlations between orbital properties and abundances, we also collected a set of abundances for barium stars with orbital elements that is as homogeneous as possible. When unavailable in the literature, abundances were derived from high-resolution HERMES spectra. Results. We find orbital motion for all barium and extrinsic S stars monitored (except for the mild barium star HD 95345). We obtain the longest period known so far for a spectroscopic binary involving an S star, namely 57 Peg with a period of the order of 100−500 yr. We present the mass distribution for the barium stars, which ranges from 1 to 3 M⊙, with a tail extending up to 5 M⊙ in the case of mild barium stars. This high-mass tail is mostly comprised of high-metallicity objects ([Fe/H] ≥ −0.1). The distribution of the companion masses was extracted from the barium-star mass distribution combined with the finding that Q ≡ f(MBa,MWD)/sin3 i = MWD3/(MBa + MWD)2 is peaked at 0.057 ± 0.009 and 0.036 ± 0.027 M⊙ for strong and mild barium stars, respectively (f(MBa, MWD) is the mass function obtained from the orbital elements of spectroscopic binaries with one observable spectrum). Mass functions are compatible with WD companions whose masses range from 0.5 to 1 M⊙. Strong barium stars have a tendency to be found in systems with shorter periods than mild barium stars, although this correlation is rather lose, with metallicity and WD mass also playing a role. Using the initial–final mass relationship established for field WDs, we derived the distribution of the mass ratio q′=MAGB, ini/MBa (where MAGB, ini is the WD progenitor initial mass, i.e., the mass of the former primary component of the system) which is a proxy for the initial mass ratio (the less mass the barium star has accreted, the better the proxy). It appears that the distribution of q′ is highly nonuniform, and significantly different for mild and strong barium stars, the latter being characterized by values mostly in excess of 1.4, whereas mild barium stars occupy the range 1−1.4. Conclusions. The orbital properties presented in this paper pave the way for a comparison with binary-evolution and nucleosynthesis models, which should account for the various significant correlations found between abundances and dynamical parameters (e.g. between MBa on one hand and MWD, [Fe/H], and [s/Fe] on the other hand, between q′ and [s/Fe], between P and e, and between P and [s/Fe] altogether).

scholarly journals SEQUENTIAL STAR FORMATION IN RCW 34: A SPECTROSCOPIC CENSUS OF THE STELLAR CONTENT OF HIGH-MASS STAR-FORMING REGIONS

2010 ◽  
Vol 713 (2) ◽  
pp. 883-899 ◽  
Author(s):  
A. Bik ◽  
E. Puga ◽  
L.B.F.M. Waters ◽  
M. Horrobin ◽  
Th. Henning ◽  
...  
Keyword(s):  
Star Formation ◽  
High Mass ◽  
Mass Star ◽  
Stellar Content ◽  
Star Forming ◽  
Star Forming Regions

Metal-organophosphine complexes: structure, bonding, and applications

2015 ◽  
Vol 35 (1) ◽  
pp. 25-56 ◽  
Author(s):  
Joe Gerald Jesu Raj
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Spectroscopic Analysis ◽  
Organophosphorus Compounds ◽  
Spectroscopic Characterization ◽  
Material Synthesis ◽  
Nanoscale Material ◽  
Phosphine Complexes ◽  
Potential Applications ◽  
Tunable Optical Properties

AbstractMetal-organophosphine complexes are very important candidates in homogeneous and heterogeneous catalysis. Many of the organophosphorus derivatives find applications in nanoscale material synthesis as important precursors. Phosphine complexes containing a variety of substituents exhibit tunable optical properties, which can be successfully applied in conjugation with nanoscale materials in solar-cell applications, photovoltaics, and the development of novel nanomaterials. In view of the emerging importance and potential applications of organophosphorus compounds, this review details the fundamental structural, synthetic, and spectroscopic characterization of organophosphines and their corresponding metal complexes. A special emphasis has been given to 31P{1H} and 1H nuclear magnetic resonance (NMR) spectroscopic analysis.

scholarly journals Binary Systems Within Star Clusters

2011 ◽  
Vol 7 (S282) ◽  
pp. 462-463
Author(s):  
Ernst Paunzen ◽  
Christian Stütz ◽  
Bernhard Baumann
Keyword(s):  
Binary Systems ◽  
Star Clusters ◽  
Variable Stars ◽  
Open Clusters ◽  
Spectroscopic Binaries ◽  
Published Data ◽  
Stellar Content ◽  
Low Mass ◽  
A Site ◽  
Database Content

AbstractWEBDA (http://www.univie.ac.at/webda) is a site devoted to observational data of stellar clusters in the Milky Way and the Small Magellanic Cloud. It is intended to provide a reliable presentation of the available data and knowledge about these objects. The success of WEBDA is documented by its worldwide usage and the related acknowledgements in the literature: more than 650 refereed publications within the last twelve years acknowledged its use. It collects all published data for stars in open clusters that may be useful either to determine membership, or to study the stellar content and properties of the clusters.The database content includes astrometric data in the form of coordinates, rectangular positions, and proper motions, photometric data in the major systems in which star clusters have been observed, but also spectroscopic data like spectral classification, radial velocities, and rotational velocities. It also contains miscellaneous types of supplementary data like membership probabilities, orbital elements of spectroscopic binaries, and periods for different kinds of variable stars as well as an extensive bibliography. Several powerful tools help to plot, query and extract the data, which can be directly retrieved via http. At the time of writing, about four million individual measurements have been included in the database. The Star Clusters Young & Old Newsletter (SCYON), a bi-monthly newsletter devoted to star cluster research with about 600 subscribers, is hosted in parallel with the database.We present the current and upcoming new interface and tools, which are needed to visualize and analyze the increasing amount of data from all-sky surveys, and deeper investigations of binary systems, low mass dwarfs, as well as planet-hosting stars.

scholarly journals 13 C-METHYL FORMATE: OBSERVATIONS OF A SAMPLE OF HIGH-MASS STAR-FORMING REGIONS INCLUDING ORION-KL AND SPECTROSCOPIC CHARACTERIZATION

2014 ◽  
Vol 215 (2) ◽  
pp. 25 ◽  
Author(s):  
Cécile Favre ◽  
Miguel Carvajal ◽  
David Field ◽  
Jes K. Jørgensen ◽  
Suzanne E. Bisschop ◽  
...  
Keyword(s):  
Methyl Formate ◽  
Spectroscopic Characterization ◽  
High Mass ◽  
Mass Star ◽  
Star Forming ◽  
Star Forming Regions

scholarly journals Non-synchronous rotations in massive binary systems

2018 ◽  
Vol 618 ◽  
pp. A174
Author(s):  
C. Putkuri ◽  
R. Gamen ◽  
N. I. Morrell ◽  
S. Simón-Díaz ◽  
R. H. Barbá ◽  
...  
Keyword(s):  
Binary Systems ◽  
Massive Stars ◽  
Spectroscopic Binaries ◽  
Evolutionary Status ◽  
Multiple Systems ◽  
Orbital Parameters ◽  
Link Type ◽  
Tidal Forces ◽  
Relative Separation ◽  
Massive Binary Systems

Context. Most massive stars are in binary or multiple systems. Several massive stars have been detected as double-lined spectroscopic binaries and among these, the OWN Survey has detected a non-negligible number whose components show very different spectral line broadening (i.e., projected rotational velocities). This fact raises a discussion about the contributing processes, such as angular-momentum transfer and tidal forces. Aims. We seek to constrain the physical and evolutionary status of one of such systems, the O+O binary HD 93343. Methods. We analyzed a series of high-resolution multiepoch optical spectra to determine the orbital parameters, projected rotational velocities, and evolutionary status of the system. Results. HD 93343 is a binary system comprised of two O7.5 Vz stars that each have minimum masses of approximately 22 M⊙ in a wide and eccentric orbit (e = 0.398±0.004; P = 50.432±0.001 d). Both stars have very similar stellar parameters, and hence ages. As expected from the qualitative appearance of the combined spectrum of the system, however, these stars have very different projected rotational velocities (~65 and ~325 km s−1, respectively). Conclusions. The orbits and stellar parameters obtained for both components seem to indicate that their youth and relative separation is enough to discard the effects of mass transfer and tidal friction. Thus, non-synchronization should be intrinsic to their formation.

scholarly journals Spectroscopic characterization of the stellar content of ultra-diffuse galaxies

2018 ◽  
Vol 478 (2) ◽  
pp. 2034-2045 ◽  
Author(s):  
T Ruiz-Lara ◽  
M A Beasley ◽  
J Falcón-Barroso ◽  
J Román ◽  
F Pinna ◽  
...  
Keyword(s):  
Spectroscopic Characterization ◽  
Stellar Content

scholarly journals The CARMENES search for exoplanets around M dwarfs

2018 ◽  
Vol 619 ◽  
pp. A32 ◽  
Author(s):  
D. Baroch ◽  
J. C. Morales ◽  
I. Ribas ◽  
L. Tal-Or ◽  
M. Zechmeister ◽  
...  
Keyword(s):  
Binary Systems ◽  
Spectroscopic Binaries ◽  
M Dwarfs ◽  
Dwarf Stars ◽  
Double Line ◽  
Orbital Parameters ◽  
Rotation Periods ◽  
Spectroscopic Binary ◽  
M Dwarf Stars ◽  
M Dwarf

Context. The CARMENES spectrograph is surveying ∼300 M dwarf stars in search for exoplanets. Among the target stars, spectroscopic binary systems have been discovered, which can be used to measure fundamental properties of stars. Aims. Using spectroscopic observations, we determine the orbital and physical properties of nine new double-line spectroscopic binary systems by analysing their radial velocity curves. Methods. We use two-dimensional cross-correlation techniques to derive the radial velocities of the targets, which are then employed to determine the orbital properties. Photometric data from the literature are also analysed to search for possible eclipses and to measure stellar variability, which can yield rotation periods. Results. Out of the 342 stars selected for the CARMENES survey, 9 have been found to be double-line spectroscopic binaries, with periods ranging from 1.13 to ∼8000 days and orbits with eccentricities up to 0.54. We provide empirical orbital properties and minimum masses for the sample of spectroscopic binaries. Absolute masses are also estimated from mass-luminosity calibrations, ranging between ∼0.1 and ∼0.6 M⊙. Conclusions. These new binary systems increase the number of double-line M dwarf binary systems with known orbital parameters by 15%, and they have lower mass ratios on average.

scholarly journals OH maser towards IRAS 06056+2131: polarization parameters and evolution status

2020 ◽  
Vol 499 (1) ◽  
pp. 1441-1449
Author(s):  
M S Darwish ◽  
A M S Richards ◽  
S Etoka ◽  
K A Edris ◽  
S M Saad ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Linear Polarization ◽  
High Mass ◽  
High Angular Resolution ◽  
Polarization Angle ◽  
Evolutionary Status ◽  
Mass Star ◽  
Magnetic Field Direction ◽  
Star Forming ◽  
The Uk

ABSTRACT We present high-angular resolution observations of OH maser emission towards the high-mass star-forming region IRAS 06056+2131. The observations were carried out using the UK radio interferometer array, Multi-Element Radio Linked Interferometer Network (MERLIN) in the OH main lines at 1665 and 1667 MHz, in addition to the OH satellite line at 1720 MHz. The results of this study reveal the small upper limit to the size of emission in the 1665-MHz line with an estimated total intensity of ∼4 Jy. We did not detect any emission from the 1667 and 1720-MHz lines. The full polarization mode of MERLIN enables us to investigate the magnetic field in the OH maser region. In this transition, a Zeeman pair is identified from which a magnetic strength of ∼−1.5 mG is inferred. Our results show that IRAS 06056+2131 is highly polarized, with ∼ 96 ${{\ \rm per\ cent}}$ circular polarization and ∼6 ${{\ \rm per\ cent}}$ linear polarization. The linear polarization angle is ∼29°, implying a magnetic field which could be aligned with the outflow direction detected towards this region, but the actual magnetic field direction has an uncertainty of up to 110° due to the possible effects of Faraday rotation. The star-forming evolutionary status of the embedded protostellar object is discussed.

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