scholarly journals HD 150136: towards one of the most massive systems?

2010 ◽  
Vol 6 (S272) ◽  
pp. 521-522
Author(s):  
Laurent Mahy ◽  
Eric Gosset ◽  
Hugues Sana ◽  
Gregor Rauw ◽  
Thomas Fauchez ◽  
...  
Keyword(s):  
Physical Parameters ◽  
Intensive Monitoring ◽  
Preliminary Results ◽  
Short Period ◽  
Period System ◽  
Orbital Solution ◽  
Three Components

AbstractWe present the preliminary results of an intensive monitoring devoted to HD 150136. Already quoted as an O3+O6 binary, we detected a third O-type component physically linked to the system, making it one of the nearest (1.3 kpc) most massive systems known until now (~134M⊙). To determine the physical parameters of this system, we applied a disentangling program to study individually the three components. It allows us to constrain their spectral types and to derive a new orbital solution for the short-period system.

scholarly journals The Photometric Study of Neglected Short-Period Eclipsing Binary BS Vulpeculae

2011 ◽  
Vol 7 (S282) ◽  
pp. 83-84
Author(s):  
Miloslav Zejda ◽  
Zdeněk Mikulášek ◽  
Liying Zhu ◽  
Shengbang Qian ◽  
Jiří Liška
Keyword(s):  
Light Curves ◽  
Physical Parameters ◽  
Photometric Study ◽  
Eclipsing Binary ◽  
Preliminary Results ◽  
Short Period

AbstractThe preliminary results of a study of a neglected, relatively bright, short-periodic (P=0.48 d), near contact eclipsing binary BS Vulpeculae is given. We present our new complete (BVRI) light curves, and physical parameters of the system based on them, derived by the 2003 version of the Wilson–Van Hamme code.

scholarly journals NEUTRONIC ANALYSIS OF THE CANDIDATE MULTI-LAYER CLADDING MATERIALS WITH ENHANCED ACCIDENT TOLERANCE FOR WWER REACTORS

2018 ◽  
Vol 14 ◽  
pp. 27 ◽  
Author(s):  
Ondřej Novák ◽  
Martin Ševeček
Keyword(s):  
Monte Carlo ◽  
Physical Parameters ◽  
Simulation Tool ◽  
Coating Materials ◽  
Preliminary Results

The paper summarizes preliminary results of neutronic analysis of candidate ATF cladding materials that are under development at the CTU in Prague. To evaluate basic neutronics-related characteristics the Serpent code was used which is a Monte-Carlo based simulation tool. A model of WWER fuel was developed and basic neutronic analysis performed. All coating materials entail certain reactivity penalty compared to reference uncoated cladding that was quantified. The coating of cladding affects also other neutron-physical parameters of cores that modify the performance of the WWER reactors that are discussed.

scholarly journals Investigation of the WR 11 field at decimeter wavelengths

2019 ◽  
Vol 625 ◽  
pp. A99 ◽  
Author(s):  
P. Benaglia ◽  
S. del Palacio ◽  
C. H. Ishwara-Chandra ◽  
M. De Becker ◽  
N. L. Isequilla ◽  
...  
Keyword(s):  
Spectral Index ◽  
Thermal Emission ◽  
Mass Loss Rate ◽  
High Energy ◽  
Low Frequencies ◽  
Nonthermal Radio ◽  
Short Period ◽  
Radiation Processes ◽  
Period System ◽  
The Individual

The massive binary system WR 11 (γ2-Velorum) has recently been proposed as the counterpart of a Fermi source. If this association is correct, this system would be the second colliding wind binary detected in GeV γ-rays. However, the reported flux measurements from 1.4 to 8.64 GHz fail to establish the presence of nonthermal (synchrotron) emission from this source. Moreover, WR 11 is not the only radio source within the Fermi detection box. Other possible counterparts have been identified in archival data, some of which present strong nonthermal radio emission. We conducted arcsec-resolution observations toward WR 11 at very low frequencies (150–1400 MHz) where the nonthermal emission – if existent and not absorbed – is expected to dominate. We present a catalog of more than 400 radio emitters, among which a significant portion are detected at more than one frequency, including limited spectral index information. Twenty-one of these radio emitters are located within the Fermi significant emission. A search for counterparts for this last group pointed at MOST 0808–471; this source is 2′ away from WR 11 and is a promising candidate for high-energy emission, having a resolved structure along 325–1390 MHz. For this source, we reprocessed archive interferometric data up to 22.3 GHz and obtained a nonthermal radio spectral index of − 0.97 ± 0.09. However, multiwavelength observations of this source are required to establish its nature and to assess whether it can produce (part of) the observed γ-rays. WR 11 spectrum follows a spectral index of 0.74 ± 0.03 from 150 to 230 GHz, consistent with thermal emission. We interpret that any putative synchrotron radiation from the colliding-wind region of this relatively short-period system is absorbed in the photospheres of the individual components. Notwithstanding, the new radio data allowed us to derive a mass-loss rate of 2.5 × 10−5 M⊙ yr−1, which, according to the latest models for γ-ray emission in WR 11, would suffice to provide the required kinetic power to feed nonthermal radiation processes.

scholarly journals Constraints on the Atmospheric Parameters of the Binary DA White Dwarf L870-2 (EG11)

1989 ◽  
Vol 114 ◽  
pp. 435-439
Author(s):  
P. Bergeron ◽  
F. Wesemael ◽  
J. Liebert ◽  
G. Fontaine ◽  
P. Lacombe
Keyword(s):  
Observational Data ◽  
Stellar Evolution ◽  
Effective Temperature ◽  
White Dwarf ◽  
Binary Systems ◽  
Absolute Magnitude ◽  
Atmospheric Parameters ◽  
Spectroscopic Binary ◽  
Short Period ◽  
Period System

The recent discovery that the cool DA white dwarf L870-2 (EG11, WD0135-052) is a double-lined spectroscopic binary composed of a detached pair of DA white dwarfs (Saffer, Liebert, and Olszewski 1988, SLO hereafter) has raised some challenging problems for stellar evolution theories of such binary systems. One first important step in the understanding of this short-period system is to establish the atmospheric parameters of each component. SLO have argued from previous determinations of the effective temperature and absolute magnitude of the system, and also from their own study of the composite Hα profile, that the two components should be similar. We wish here to reexamine this assertion by taking a new look at the constraints on the two components brought about by the available observational data.

scholarly journals The Evolution of Jupiter Family Comets over 2000 Years

1992 ◽  
Vol 152 ◽  
pp. 269-274 ◽  
Author(s):  
G. Tancredi ◽  
H. Rickman
Keyword(s):  
Data Base ◽  
Orbital Evolution ◽  
Physical Parameters ◽  
Time Interval ◽  
Orbital Elements ◽  
Present Epoch ◽  
Numerical Integrations ◽  
Short Period

The orbital evolution of the whole sample sample of short-period comets was computed by numerical integrations for a time interval of 2000 yr centered on the present epoch. This data base is intended to serve in various studies involving the statistics of orbital evolution and correlation with physical parameters or discovery circumstances. We present some results concerning the following aspects: the evolution of the orbital elements and their past-future asymmetry, statistics on the discovery of comets and on the encounters of comets with Jupiter.

scholarly journals A survey for high-mass eclipsing binaries

2019 ◽  
Vol 490 (4) ◽  
pp. 5147-5173
Author(s):  
F Pozo Nuñez ◽  
R Chini ◽  
A Barr Domínguez ◽  
Ch Fein ◽  
M Hackstein ◽  
...  
Keyword(s):  
Eclipsing Binaries ◽  
Light Curves ◽  
High Mass ◽  
System Component ◽  
Fundamental Parameters ◽  
Average Value ◽  
Short Period ◽  
Orbital Periods ◽  
Photometric Monitoring ◽  
Period System

ABSTRACT We report results from a search for Galactic high-mass eclipsing binaries. The photometric monitoring campaign was performed in Sloan r and i with the robotic twin refractor RoBoTT at the Universitätssternwarte Bochum in Chile and complemented by Johnson UBV data. Comparison with the SIMBAD data base reveals 260 variable high-mass stars. Based on well-sampled light curves, we discovered 35 new eclipsing high-mass systems and confirm the properties of six previously known systems. For all objects, we provide the first light curves and determine orbital periods through the Lafler–Kinman algorithm. Apart from GSC 08173-0018 and Pismis 24-13 ($P = 19.47\, d$ and $20.14\, d$) and the exceptional short-period system TYC 6561-1765-1 ($P = 0.71\, d$), all systems have orbital periods between 1 and 9 d. We model the light curves of 26 systems within the framework of the Roche geometry and calculate fundamental parameters for each system component. The Roche lobe analysis indicates that 14 systems have a detached geometry, while 12 systems have a semidetached geometry; seven of them are near-contact systems. The deduced mass ratios q = M2/M1 reach from 0.4 to 1.0 with an average value of 0.8. The similarity of masses suggests that these high-mass binaries were created during the star formation process rather than by tidal capture.

scholarly journals A Flare-Like Event from the Short-Period System XY UMa

1983 ◽  
Vol 71 ◽  
pp. 411-413
Author(s):  
M. Zeilik ◽  
R. Elston ◽  
G. Henson ◽  
P. Smith
Keyword(s):  
Light Curve ◽  
Light Curves ◽  
Active System ◽  
Primary Star ◽  
Rs Cvn Stars ◽  
Short Period ◽  
Annual Changes ◽  
Period System ◽  
Photoelectric Observations

XY UMa (+55°1317, SA027143) is a short-period (P 0.48 d) cousin of the RS CVn stars. The primary star is G2-G5V; the secondary K5 (Geyer, quoted by Lorenzi and Scaltriti, 1977). Geyer (1977) has done the bulk of the observational work to date, including the first photoelectric observations. The rapid, annual changes in XY UMa's light curve, and the fact that the last published light curves was from the 1977 season convinced us to reobserve this active system.

scholarly journals Transit & RV Observations of Exoplanets by the 1-m Telescope at Weihai

2012 ◽  
Vol 8 (S293) ◽  
pp. 33-35
Author(s):  
Chen Cao ◽  
Dayong Ren ◽  
Dongyang Gao ◽  
Jicheng Zhang ◽  
Nan Song ◽  
...  
Keyword(s):  
High Resolution ◽  
Radial Velocity ◽  
Extrasolar Planets ◽  
Physical Parameters ◽  
Velocity Measurements ◽  
Preliminary Results

AbstractBy using the 1-m reflecting telescope at Weihai Observatory of Shandong University, the transit observations of seven stars are carried out to accurately estimate the physical parameters of extrasolar planets. Besides, a new high-resolution spectrograph (WES) was installed on this telescope for radial velocity measurements on exoplanets, we will show some preliminary results.

Radio wave Doppler studies of the Antarctic ionosphere

1977 ◽  
Vol 279 (963) ◽  
pp. 239-246 ◽  
Keyword(s):  
Energy Balance ◽  
Radio Wave ◽  
Antarctic Peninsula ◽  
Current Knowledge ◽  
Doppler Studies ◽  
Preliminary Results ◽  
Short Period ◽  
The Antarctic

The occurence of propagating wave-like disturbances in the atmosphere at ionospheric heights is well documented, but their causes and role in the energy balance of the atmosphere is poorly understood. This paper describes an experiment deployed in the Antarctic Peninsula region to investigate the morphology of the various classes of disturbance, with particular emphasis on the identification of their sources. Current knowledge of the phenomena is briefly reviewed and the reasons why observations in the peninsula region may be especially valuable are discussed. Some preliminary results from the first 3 months of operation are presented; these indicate the presence of waves with periods ranging from less than 1 min to more than 90 min. The short period waves (1-5 min) are unusually common in these data.

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