Filters
Results 1 - 10 of 3223
Results 1 - 10 of 3223.
Search took: 0.025 seconds
Sort by: date | relevance |
AbstractAbstract
[en] We examine the recent star formation associated with four supergiant shells in the Large Magellanic Cloud (LMC): LMC 1, 4, 5, and 6, which have been shown to have simple expanding-shell structures. H II regions and OB associations are used to infer star formation in the last few Myr, while massive young stellar objects reveal the current ongoing star formation. Distributions of ionized H I and molecular components of the interstellar gas are compared with the sites of recent and current star formation to determine whether triggering has taken place. We find that a great majority of the current star formation has occurred in gravitationally unstable regions, and that evidence of triggered star formation is prevalent at both large and local scales.
Primary Subject
Source
Available from http://dx.doi.org/10.1088/0004-6256/137/3/3599; Country of input: International Atomic Energy Agency (IAEA)
Record Type
Journal Article
Journal
Astronomical Journal (New York, N.Y. Online); ISSN 1538-3881;
; v. 137(3); p. 3599-3605

Country of publication
Reference NumberReference Number
INIS VolumeINIS Volume
INIS IssueINIS Issue
AbstractAbstract
[en] By a comparison of Trapezium-type multiple star systems in the Abastumani Catalogue and the famous Catalogue of Stellar Associations and Clusters, it is confirmed that the great number of Trapezium-type multiple stars, which belong mostly to spectral classes O-B2, are found in associations and clusters. In 13 T-associations, 120 Trapezium-type multiple systems and 182 common multiple and double stars could be detected. Based on present-day observational data and the author's photographic observations, the kinematic of Trapezium-type multiple stars of spectral class O-B2 is studied. (Auth.)
Primary Subject
Source
Kopal, Z.; Rahe, J. (eds.); Astrophysics and space science library; v. 98; 531 p; ISBN 90-277-1436-3;
; 1982; p. 109-113; D. Reidel; Dordrecht (Netherlands); 69. Colloquium of the IAU on binary and multiple stars as tracers of stellar evolution; Bamberg (Germany, F.R.); 31 Aug - 3 Sep 1981

Record Type
Book
Literature Type
Conference
Country of publication
Reference NumberReference Number
INIS VolumeINIS Volume
INIS IssueINIS Issue
AbstractAbstract
[en] Even though it is likely that the process of creation of an inverted electron distribution in the slowly converging magnetic field lines would not arise because of the fast destruction of anisotropy by collisions, it is possible that a rapid build-up of an inverted population, as might occur in a shock transition, could be preserved for a relatively long time by means of transfer of momentum, rather than energy, from an inverted population of protons
Primary Subject
Record Type
Journal Article
Journal
Proceedings - Astronomical Society of Australia; ISSN 0066-9997;
; v. 4(4); p. 370-371

Country of publication
Reference NumberReference Number
INIS VolumeINIS Volume
INIS IssueINIS Issue
Medin, Zach; Cumming, Andrew, E-mail: zmedin@physics.mcgill.ca, E-mail: cumming@physics.mcgill.ca2011
AbstractAbstract
[en] We discuss the effect of chemical separation as matter freezes at the base of the ocean of an accreting neutron star, and argue that the retention of light elements in the liquid acts as a source of buoyancy that drives a slow but continual mixing of the ocean, enriching it substantially in light elements, and leading to a relatively uniform composition with depth. We first consider the timescales associated with different processes that can redistribute elements in the ocean, including convection, sedimentation, crystallization, and diffusion. We then calculate the steady-state structure of the ocean of a neutron star for an illustrative model in which the accreted hydrogen and helium burn to produce a mixture of O and Se. Even though the H/He burning produces only 2% oxygen by mass, the steady-state ocean has an oxygen abundance more than 10 times larger, almost 40% by mass. Furthermore, we show that the convective motions transport heat inward, with a flux of ∼0.2 MeV nucleon-1 for an O-Se ocean, heating the ocean and steepening the outward temperature gradient. The enrichment of light elements and heating of the ocean due to compositionally driven convection likely have important implications for carbon ignition models of superbursts.
Primary Subject
Source
Available from http://dx.doi.org/10.1088/0004-637X/730/2/97; Country of input: International Atomic Energy Agency (IAEA)
Record Type
Journal Article
Journal
Country of publication
Reference NumberReference Number
INIS VolumeINIS Volume
INIS IssueINIS Issue
AbstractAbstract
[en] After discussing the basic facts about geometrically thin accretion discs, the authors discuss the motivations which have led to the theory of geometrically thick ones and present their main properties. They review the observational evidence for the existence of thick accretion discs, concentrating on recent results in the extragalactic context
Primary Subject
Secondary Subject
Source
Cerdonio, M.; Toller, M. (Univ. of Trento (Italy)); Cianci, R. (Univ. of Genova (Italy)); Francaviglia, M. (Univ. of Torino (Italy)); 630 p; ISBN 9971-50-844-3;
; 1988; p. 102-123; World Scientific Pub. Co; Teaneck, NJ (USA); 8. Italian conference on general relativity and gravitational physics; Cavalese (Italy); 30 Aug - 3 Sep 1988; CONF-8808304--; World Scientific Pub. Co., 687 Hartwell Street, Teaneck, NJ 07666 (USA)

Record Type
Book
Literature Type
Conference
Country of publication
Reference NumberReference Number
INIS VolumeINIS Volume
INIS IssueINIS Issue
AbstractAbstract
[en] Results of analytical study of early stages of a single star evolution are used investigation of the rotational fragmentation of the collapsing gas-dust cloud which leads to formation of two types of binaries. Wide α-systems (Psub(orb) > or approximately 100 yrs) with usually unequal masses of components are formed before the formation of gas-dust core in hydrostatical equilibrium. Close ß-systems (Psub(orb) < or approximation 100 yrs) with usually nearly equal masses of components are formed in the course of the collapse of gas-dust core
Original Title
Obrazovanie dvojnykh zvezd
Primary Subject
Source
For English translation see the journal Soviet Astronomy Letters (USA).
Record Type
Journal Article
Journal
Pis'ma v Astronomicheskij Zhurnal; ISSN 0320-0108;
; v. 9(3); p. 160-165

Country of publication
Reference NumberReference Number
INIS VolumeINIS Volume
INIS IssueINIS Issue
AbstractAbstract
[en] The purpose of this note is to present preliminary results of deceleration calculations for matter infalling onto strongly magnetized neutron star. We discuss the validity of both models of thermalization. It has been found that for accretion rates > or approx. 105 gr.cm-2 sec-1, stationary, collisionless shock solutions do not exist. (orig.)
Primary Subject
Source
Brinkmann, W.; Truemper, J. (eds.); Max-Planck-Institut fuer Physik und Astrophysik, Garching (Germany, F.R.). Inst. fuer Extraterrestrische Physik; 337 p; Oct 1982; p. 289-292; Workshop on accreting neutron stars; Garching (Germany, F.R.); 19 - 23 Jul 1982
Record Type
Report
Literature Type
Conference
Report Number
Country of publication
Reference NumberReference Number
INIS VolumeINIS Volume
INIS IssueINIS Issue
AbstractAbstract
[en] Some questions concerning formation and early evolution of protoplanetary disks around single solar type stars are discussed. A new class of models of circumstellar protoplanetary disks are proposed, the parameters of the model being the disk's mass and angular momentum and the central star's mass and luminosity. Since disks probably exist for a long time (up to 100 million years), it would be interesting to search for them about stars in disintegrating clusters
[ru]
Original Title
Modeli protoplanetnykh diskov okolo zvezd klassov F-G
Primary Subject
Source
For English translation see the journal Soviet Astronomy Letters (USA).
Record Type
Journal Article
Journal
Pis'ma v Astronomicheskij Zhurnal; ISSN 0320-0108;
; v. 8(6); p. 371-377

Country of publication
Reference NumberReference Number
INIS VolumeINIS Volume
INIS IssueINIS Issue
AbstractAbstract
[en] We study the 205.9 Hz pulsations of the accreting millisecond X-ray pulsar NGC 6440 X-2 across all outbursts observed with the Rossi X-ray Timing Explorer over a period of 800 days. We find the pulsations are highly sinusoidal with a fundamental amplitude of 5%–15% rms and a second harmonic that is only occasionally detected with amplitudes of ≲2% rms. By connecting the orbital phase across multiple outbursts, we obtain an accurate orbital ephemeris for this source and constrain its 57 minute orbital period to sub-millisecond precision. We do not detect an orbital period derivative to an upper limit of We investigate the possibility of coherently connecting the pulse phase across all observed outbursts, but find that due to the poorly constrained systematic uncertainties introduced by a flux-dependent bias in the pulse phase, multiple statistically acceptable phase-connected timing solutions exist.
Primary Subject
Source
Available from http://dx.doi.org/10.1088/0004-637X/814/2/138; Country of input: International Atomic Energy Agency (IAEA); Since 2009, the country of publication for this journal is the UK.
Record Type
Journal Article
Journal
Country of publication
Reference NumberReference Number
INIS VolumeINIS Volume
INIS IssueINIS Issue
AbstractAbstract
[en] Hypersonic accretion flow in two dimensions from an infinite medium which contains a small density and/or velocity gradient is considered. To first order in rsub(a)/h, where rsub(a) is the accretion radius and h the scale of the gradient, the accretion rate is unaffected and the accreted angular momentum is zero. Thus previous estimates of the amount of angular momentum accreted may severely overestimate the actual value. (author)
Primary Subject
Record Type
Journal Article
Journal
Monthly Notices of the Royal Astronomical Society; ISSN 0035-8711;
; v. 191(2); p. 599-604

Country of publication
Reference NumberReference Number
INIS VolumeINIS Volume
INIS IssueINIS Issue
1 | 2 | 3 | Next |