Explanipedia

The recurrent nova U Scorpii - an evolutionary considerations Open

M. J. Sarna, E. Ergma, Jelena Greskevits · 2005

We perform evolutionary calculations of binary stars to find progenitors of systems with parameters similar to the recurrent nova U Sco. We show that a U Sco-type system may be formed starting with an initial binary system which has a low-…

Eclipsing binary millisecond pulsar PSR J1740-5340 – evolutionary considerations andobservational test Open

E. Ergma, M. J. Sarna · 2003

Physics Mathematics

\n We perform evolutionary calculations for a binary\nsystem to produce observed binary parameters for the PSR J1740–5340. Our calculations support the model proposed by\nD'Amico et al. (2001) in which this binary may be the progenitor\nof…

Is KPD 1930+2752 a good candidate type Ia supernova progenitor? Open

E. Ergma, A. V. Fedorovа, L. R. Yungelson · 2001

Physics Mathematics Computer science

We investigate the evolution of a binary system which initially has an orbital period of 2^h 17^m and contains a 0.5 M_sun helium star with a white dwarf companion of 0.97 M_sun, similarly to suggested SN Ia candidate progenitor KPD 1930+2…

What can we learn from the surface chemical composition of the optical companions of Soft X-ray transients? Open

E. Ergma, S J Sarna · 2001

Physics Mathematics Art

Several evolutionary sequences with low--mass secondaries ($M_d $=1.25, 1.5 and 1.7$ M_\odot $) and black hole accretors ($M_{bh} $=5 and 10$ M_\odot$) are calculated. The angular momentum losses due to magnetic braking and gravitational w…

What can we learn from the surface chemical composition of the optical companions of Soft X-ray transients? Open

E. Ergma, M. J. Sarna · 2001

Physics Philosophy

\n \n Several evolutionary sequences with low-mass secondaries \n($M_{\\rm d}=1.25$, 1.5 and 1.7 $M_\\odot$) and black hole accretors \n($M_{\\rm bh}=5$ and 10 $M_\\odot$) are calculated. The angular momentum \nlosses due to magnetic braki…

The helium white dwarf in two pulsars: too cool in PSR J0751+1807 and too hot in PSR J1012+5307? Open

E. Ergma, M. J. Sarna, J. Gerskevits-Antipova · 2001

Physics

We discuss the cooling history of the low-mass, helium core white dwarfs in short orbital period millisecond pulsars PSR J0751+1807 and PSR J1012+5307. The revised cooling age estimated by Alberts et al. agrees with the age estimation for …

The eclipsing binary millisecond pulsar PSR B1744-24A - possible test for a magnetic braking mechanism Open

E. Ergma, M. J. Sarna · 2000

Physics Engineering

As presented by Nice et al. (2000), long-term timing of the eclipsing binary PSR B1744-24A shows that the orbital period of this system decreases with a time-scale of only ~ 200 Myr. To explain the much faster orbital period decay than tha…

An evolutionary scenario for the U Scorpii Open

E. Ergma, Jelena Gerškevitš, M. J. Sarna · 2000

Physics Mathematics

We perform evolutionary calculations of binary stars to find progenitors of systems with parameters similar to the recurrent novae U Sco. We show that a U Sco type-system may be formed starting with an initial binary system which has a low…

Cooling curves and initial models for low-mass white dwarfs (<0.25 M ) with helium cores Open

M. J. Sarna, E. Ergma, J. Gerskevits-Antipova · 2000

Physics Computer science

We present a detailed calculation of the evolution of low-mass ($< 0.25~M_\odot $) helium white dwarfs. These white dwarfs (the optical companions to binary millisecond pulsars) are formed via long-term, low-mass binary evolution. After de…

Helium white dwarf cooling in PSR J0751+1807 and PSR J1012+5307 Open

E. Ergma, J. Antipova, M. J. Sarna · 2000

Physics

It is accepted that formation of a binary millisecond (or recycled) pulsar with a low–mass companion may be explained as the end–point of close binary evolution in which an old pulsar is spun–up by accretion from the secondary (Alpar et al…

Low–Mass He WDs and Millisecond Pulsars Age Determination Open

J. Antipova, E. Ergma, M. J. Sarna · 2000

Physics

It is accepted that the formation of a millisecond binary pulsar (MBP) with a low–mass companion may be explained as the end–point of close binary evolution in which an old pulsar is spun–up by accretion from the red giant (Bhattacharaya &…

An evolutionary model for SAX J1808.4 -- 3658 Open

E. Ergma, J. Antipova · 1999

Physics

An evolutionary scenario to explain the transient nature and short total duration of the X-ray burst of SAX J1808.4 -- 3658 is proposed. An optical companion of the neutron star (a ``turn-off'' Main - Sequence star) fills its Roche lobe at…

The evolution of short-period binary pulsars: a systematic study Open

E. Ergma, M. J. Sarna, J. Antipova · 1998

Physics Mathematics

We present evolutionary sequences for low-mass close binary systems in which a low-mass (1.0–1.5 M⊙) secondary star transfers mass to a neutron star. Roche lobe filling occurs when the secondary is a turn-off main-sequence star (having a s…

Evolution of black hole low-mass binaries Open

E. Ergma, A. V. Fedorovа · 1998

Physics Computer science Mathematics

Several evolutionary sequences with low mass sec- ondaries as donors and black holes as accretors are calculated. Adopting a simple estimate for the efficiency of magnetic brak- ing we have determined the bifurcation period Pbif , separati…

Formation of Low-Mass Black Hole X-Ray Transients Open

Simon Portegies Zwart, F. Verbunt, E. Ergma · 1998

Physics Computer science

We study the formation of low-mass X-ray binaries with a black hole as accreting object. The performed semi-analytic analysis reveals that the formation rate of black holes in low-mass X-ray binaries is about two orders of magnitude smalle…

Cyg X-3: can the compact object be a black hole? Open

E. Ergma, Lev R. Yungelson · 1997

Physics Computer science

By means of population synthesis we find that the expected Galactic number of black holes with massive helium star companions is \sim 100 and depends on an assumed threshold for M_{pre-BH}. The overwhelming majority of these systems has or…

Formation of Low-mass Black Hole X-ray Transients Open

Simon Portegies Zwart, F. Verbunt, E. Ergma · 1997

Physics Mathematics Computer science

We study the formation of low-mass X-ray binaries with a black hole as accreting object. The performed semi-analytic analysis reveals that the formation rate of black holes in low-mass X-ray binaries is about two orders of magnitude smalle…

A Millisecond Pulsar Progenitor to an Ultracompact Low-mass X-Ray Binary Open

E. Ergma, S. C. Lundgren, J. M. Cordes · 1997

Physics Engineering

With a pulsar timing baseline of 10 years, the orbital period decay due to gravitational radiation will be measurable for the recently discovered short orbital period millisecond pulsar PSR J0751+1807. This is the first white dwarf-neutron…

The formation of black-holes in low-mass X-ray binaries Open

Simon Portegies Zwart, F. Verbunt, E. Ergma · 1997

Physics Computer science Mathematics

We calculate the formation rates of low-mass X-ray binaries with a black hole. Both a semi-analytic and a more detailed model predict formation rates two orders of magnitude lower than derived from the observations. Solution of this conund…

List of participants Open

I. V. Andronov, Philip J. Armitage, Odessa Ioa, Raymundo Baptistastsc, Bard , et al. · 1996

Computer science Psychology Mathematics

An abstract is not available for this content so a preview has been provided. As you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

Debate: The Origin and Evolution of Millisecond Pulsars Open

M. Bailes, E. Ergma, A. G. Lyne, Frederic A. Rasio, Ed van den Heuvel , et al. · 1996

Computer science Physics Mathematics

An abstract is not available for this content so a preview has been provided. As you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

An Evolutionary Scenario for Short Period (≤10 Days) Millisecond Binary Pulsars Open

E. Ergma, M. J. Sarna, J. Antipova · 1996

Physics Biology Mathematics

We present numerical calculations that simulate the evolution of a low mass (1M ⊙ ) star transfering mass to a compact object (Muslimov & Sarna 1993; Ergma & Sarna 1996). Mass transfer starts when the secondary turns off the main sequence …

The Evolutionary Status of PSR 1718–19 Open

E. Ergma, M. J. Sarna · 1996

Physics Biology Mathematics

Possible models for the matter source inside the eclipsing binary system PSR 1718–19, and for the evolution of this system are reviewed, including Zwitter's (1993) stripped main-sequence (MS) turnoff star model. Both the accretion induced …

A Millisecond Pulsar Progenitor to an Ultra-Compact Low-Mass X-ray Binary Open

S. C. Lundgren, E. Ergma, J. M. Cordes · 1996

Physics Mathematics

We discuss a twist in binary neutron star evolution scenarios in which a millisecond pulsar system is actually a progenitor for a low-mass X-ray binary system. After 7 billion years of orbital decay due to gravitational radiation, the mill…

Thermonuclear Explosion in Binaries: White Dwarf Helium Star Open

E. Ergma, A. V. Fedorovа, A. M. Khohlov · 1989

Physics

Evolutionary sequences of a binary system consisting of a helium star in the stage of core helium burning and a white dwarf are presented. Different ways of He burning in the envelope of a dwarf are discussed. Incomplete helium burning is …

Thermonuclear Burning in the Envelope of an Accreting Neutron Star Open

E. Ergma, T. Tutukov · 1980

Physics Computer science

A simple analytical method has been used to investigate thermonuclear flashes in a degenerate envelope of an accreting neutron star. The heating source is the compression of envelope and the cooling is due to the radiative cooling of the e…

Hydrogen and Helium Burning in the Degenerate Envelopes of C–O Dwarfs Open

E. Ergma, А. В. Тутуков · 1979

Physics Materials science Mathematics

In our previous papers (Tutukov, Ergma, 1979; Ergma and Tutukov, 1979) we have proposed a simple analytical method to investigate the thermal evolution of shells accreted onto the surface of a neutron star. We have used this method for inv…

Evolution of a Degenerate Component in a Close Binary System Open

E. Ergma · 1979

Physics Mathematics

Investigation of evolution of a degenerate component (helium or carbon-oxygen dwarf) in a close binary system is rather important. Such dwarfs may be candidates for nova or supernova stars. The first possibility has been studied by several…

E. Ergma YOU? Author Swipe