scholarly journals A tidally tilted sectoral dipole pulsation mode in the eclipsing binary TIC 63328020

2021 ◽  
Author(s):  
S A Rappaport ◽  
D W Kurtz ◽  
G Handler ◽  
D Jones ◽  
L A Nelson ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Orbital Period ◽  
Mode Frequency ◽  
Prior History ◽  
Dipole Mode ◽  
Eclipsing Binary ◽  
Pulsation Mode ◽  
The Third ◽  
History Of ◽  
Binary Evolution

Abstract We report the discovery of the third tidally tilted pulsator, TIC 63328020. Observations with the TESS satellite reveal binary eclipses with an orbital period of 1.1057 d, and δ Scuti-type pulsations with a mode frequency of 21.09533 d−1. This pulsation exhibits a septuplet of orbital sidelobes as well as a harmonic quintuplet. Using the oblique pulsator model, the primary oscillation is identified as a sectoral dipole mode with l = 1, |m| = 1. We find the pulsating star to have M1 ≃ 2.5 M⊙, R1 ≃ 3 R⊙, and Teff, 1 ≃ 8000 K, while the secondary has M2 ≃ 1.1 M⊙, R2 ≃ 2 R⊙, and Teff, 2 ≃ 5600 K. Both stars appear to be close to filling their respective Roche lobes. The properties of this binary as well as the tidally tilted pulsations differ from the previous two tidally tilted pulsators, HD74423 and CO Cam, in important ways. We also study the prior history of this system with binary evolution models and conclude that extensive mass transfer has occurred from the current secondary to the primary.

scholarly journals Prospects for the Discovery of Black Hole Binaries without Mass Accretion with Gaia

2016 ◽  
Vol 12 (S324) ◽  
pp. 41-42
Author(s):  
Norita Kawanaka ◽  
Masaki Yamaguchi ◽  
Tsvi Piran ◽  
Tomasz Bulik
Keyword(s):  
Mass Transfer ◽  
Black Holes ◽  
Black Hole ◽  
Orbital Period ◽  
Proper Motion ◽  
Binary Systems ◽  
Evolution Model ◽  
Black Hole Binaries ◽  
Black Hole Binary ◽  
Binary Evolution

AbstractWe study the prospect for Gaia to detect black hole binary systems without the mass transfer from their companion stars. Gaia will be able to discover Galactic black holes without mass accretion by detecting the proper motion of their companion stars. We evaluate the number of such black hole binaries which have the orbital period short enough to be detected by Gaia during its operation, taking into account the binary evolution model.

scholarly journals Influence of the initial orbital period and accretion efficiency on the low-mass binary evolution

2021 ◽  
pp. 25-30
Author(s):  
J. Petrovic
Keyword(s):  
Mass Transfer ◽  
Orbital Period ◽  
White Dwarf ◽  
Binary Systems ◽  
Evolutionary Models ◽  
Stable Case ◽  
Long Period ◽  
Low Mass ◽  
Orbital Periods ◽  
Binary Evolution

This paper presents detailed evolutionary models of low-mass binary systems (1.25 + 1 M?) with initial orbital periods of 10, 50 and 100 days and accretion efficiency of 10%, 20%, 50%, and a conservative assumption. All models are calculated with the MESA (Modules for Experiments in Stellar Astrophysics) evolutionary code. We show that such binary systems can evolve via a stable Case B mass transfer into long period helium white dwarf systems.

scholarly journals Observed binary populations reflect the Galactic history

2020 ◽  
Vol 641 ◽  
pp. A163 ◽  
Author(s):  
J. Vos ◽  
A. Bobrick ◽  
M. Vučković
Keyword(s):  
Mass Transfer ◽  
Main Sequence ◽  
Fine Tuning ◽  
Red Giants ◽  
Core Mass ◽  
The Galaxy ◽  
History Of ◽  
Low Mass ◽  
Orbital Periods ◽  
Binary Evolution

Context. Wide hot subdwarf B (sdB) binaries with main-sequence companions are outcomes of stable mass transfer from evolved red giants. The orbits of these binaries show a strong correlation between their orbital periods and mass ratios. The origins of this correlation have, so far, been lacking a conclusive explanation. Aims. We aim to find a binary evolution model which can explain the observed correlation. Methods. Radii of evolved red giants, and hence the resulting orbital periods, strongly depend on their metallicity. We performed a small but statistically significant binary population synthesis study with the binary stellar evolution code MESA. We used a standard model for binary mass loss and a standard metallicity history of the Galaxy. The resulting sdB systems were selected based on the same criteria as was used in observations and then compared with the observed population. Results. We have achieved an excellent match to the observed period-mass ratio correlation without explicitly fine-tuning any parameters. Furthermore, our models produce a very good match to the observed period-metallicity correlation. We predict several new correlations, which link the observed sdB binaries to their progenitors, and a correlation between the orbital period, metallicity, and core mass for subdwarfs and young low-mass helium white dwarfs. We also predict that sdB binaries have distinct orbital properties depending on whether they formed in the Galactic bulge, thin or thick disc, or the halo. Conclusions. We demonstrate, for the first time, how the metallicity history of the Milky Way is imprinted in the properties of the observed post-mass transfer binaries. We show that Galactic chemical evolution is an important factor in binary population studies of interacting systems containing at least one evolved low-mass (Minit <  1.6 M⊙) component. Finally, we provide an observationally supported model of mass transfer from low-mass red giants onto main-sequence stars.

scholarly journals Low–Mass He WDs and Millisecond Pulsars Age Determination

2000 ◽  
Vol 177 ◽  
pp. 631-632
Author(s):  
J. Antipova ◽  
Ene Ergma ◽  
M. J. Sarna
Keyword(s):  
Neutron Stars ◽  
Orbital Period ◽  
Time Scale ◽  
Age Determination ◽  
Close Binary ◽  
Orbital Parameters ◽  
History Of ◽  
Low Mass ◽  
Binary Evolution ◽  
Red Giant

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 &amp; van den Heuvel 1991). In this paper we shall discuss the cooling properties of the helium white dwarfs (WD) in short orbital period MBP systems PSR J0437–4715, PSR J0751+1807 and PSR J1012+5307, without referring to the rotational history of neutron stars (NS).Below we discuss observational data for several system for which the results of our calculations (Sarna, Antipova, &amp; Muslimov 1998; Sarna, Ergma, &amp; Antipova 1999) may be applied, by taking into account the orbital parameters of the system, the pulsar spin-down time, and the WD cooling time-scale.

scholarly journals VV Orionis: A Well-Behaved Early-Type Eclipsing Binary System

1984 ◽  
Vol 80 ◽  
pp. 163-170
Author(s):  
Carlson R. Chambliss
Keyword(s):  
Binary System ◽  
Orbital Period ◽  
Type Systems ◽  
Early Type ◽  
Orbital Elements ◽  
Eclipsing Binary ◽  
The Third ◽  
Spectral Class ◽  
Limb Darkening ◽  
Good Agreement

AbstractVV Orionis is a detached eclipsing binary system consisting of stars of spectral types BI V and B4 V with a period of l.d4854. There is also a third component whose orbital period about the eclipsing pair is about 120 days. In recent years there have been several new photoelectric and spectroscopic investigations of this system, and the results of these are compared. Both the geometric and photometric orbital elements appear to be well determined. VV Ori A appears to be of normal size and mass for its spectral class, but VV Ori B seems to be somewhat smaller than would be expected for a normal B4 V star. Linear limb-darkening coefficients are derived for VV Ori A, and these are in good agreement with theory. This system is of particular importance, because it is only one of very few early-type systems for which reliable limb-darkening coefficients can be expected to be obtained. The contribution of the light of the third component to the system has also been determined, and it appears most likely that VV Ori C is a star of spectral type A3 V.

Subacute sclerosing panencephalitis: a rare cause of acute cortical visual impairment in an adult

2020 ◽  
Vol 50 (4) ◽  
pp. 354-358
Author(s):  
HMMTB Herath ◽  
Shanika Nandasiri ◽  
Amila Chandrakumara ◽  
Jude Jayamaha ◽  
Sunethra Senanayake ◽  
...  
Keyword(s):  
Visual Impairment ◽  
Endemic Area ◽  
Metabolic Disorders ◽  
Subacute Sclerosing Panencephalitis ◽  
Prior History ◽  
Adult Onset ◽  
The Third ◽  
Acute Visual Loss ◽  
History Of ◽  
Cortical Visual Impairment

Adult onset subacute sclerosing panencephalitis (SSPE) after the third decade of life is rare and the manifestations can mimic disorders such as dysmyelinating and metabolic disorders. This case report presents a patient with acute binocular visual impairment in his fifth decade as the first manifestation of SSPE. This is preventable with immunisation against measles. A prior history of measles infection may not be forthcoming in adult onset SSPE. This should be kept in mind as a differential diagnosis when a patient from endemic area presents with acute visual loss even in the absence of classic features. Periodic generalised discharges on the EEG without myoclonus may be seen in this condition rarely as in this case.

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

2000 ◽  
Vol 177 ◽  
pp. 637-640
Author(s):  
Ene Ergma ◽  
J. Antipova ◽  
M. J. Sarna
Keyword(s):  
Orbital Period ◽  
White Dwarf ◽  
Close Binary ◽  
Cooling History ◽  
Dipole Radiation ◽  
Spin Period ◽  
Binary Pulsars ◽  
History Of ◽  
Low Mass ◽  
Binary Evolution

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., 1982). After detachment from the Roche lobe, the pulsar spin period starts to change due to magneto–dipole radiation and the white dwarf begins to cool down. In this paper we shall discuss the cooling history of helium core low–mass white dwarfs in the short orbital period millisecond binary pulsars PSR J0751+1807 and PSR J1012+5307 (Ergma, Sarna, &amp; Antipova 1999).

scholarly journals REACT-1 round 11 report: low prevalence of SARS-CoV-2 infection in the community prior to the third step of the English roadmap out of lockdown

2021 ◽  
Author(s):  
Steven Riley ◽  
David J Haw ◽  
Caroline E Walters ◽  
Howei Wang ◽  
Oliver Eales ◽  
...  
Keyword(s):  
Sequence Data ◽  
Vaccine Coverage ◽  
Prior History ◽  
Natural Immunity ◽  
Cross Sectional ◽  
Asian Ethnicity ◽  
Epidemic Dynamics ◽  
The Third ◽  
History Of ◽  
Community Transmission

Background National epidemic dynamics of SARS-CoV-2 infections are being driven by: the degree of recent indoor mixing (both social and workplace), vaccine coverage, intrinsic properties of the circulating lineages, and prior history of infection (via natural immunity). In England, infections, hospitalisations and deaths fell during the first two steps of the 'roadmap' for exiting the third national lockdown. The third step of the roadmap in England takes place on 17 May 2021. Methods We report the most recent findings on community infections from the REal-time Assessment of Community Transmission-1 (REACT-1) study in which a swab is obtained from a representative cross-sectional sample of the population in England and tested using PCR. Round 11 of REACT-1 commenced self-administered swab-collection on 15 April 2021 and completed collections on 3 May 2021. We compare the results of REACT-1 round 11 to round 10, in which swabs were collected from 11 to 30 March 2021. Results Between rounds 10 and 11, prevalence of swab-positivity dropped by 50% in England from 0.20% (0.17%, 0.23%) to 0.10% (0.08%, 0.13%), with a corresponding R estimate of 0.90 (0.87, 0.94). Rates of swab-positivity fell in the 55 to 64 year old group from 0.17% (0.12%, 0.25%) in round 10 to 0.06% (0.04%, 0.11%) in round 11. Prevalence in round 11 was higher in the 25 to 34 year old group at 0.21% (0.12%, 0.38%) than in the 55 to 64 year olds and also higher in participants of Asian ethnicity at 0.31% (0.16%, 0.60%) compared with white participants at 0.09% (0.07%, 0.11%). Based on sequence data for positive samples for which a lineage could be identified, we estimate that 92.3% (75.9%, 97.9%, n=24) of infections were from the B.1.1.7 lineage compared to 7.7% (2.1%, 24.1%, n=2) from the B.1.617.2 lineage. Both samples from the B.1.617.2 lineage were detected in London from participants not reporting travel in the previous two weeks. Also, allowing for suitable lag periods, the prior close alignment between prevalence of infections and hospitalisations and deaths nationally has diverged. Discussion We observed marked reductions in prevalence from March to April and early May 2021 in England reflecting the success of the vaccination programme and despite easing of restrictions during lockdown. However, there is potential upwards pressure on prevalence from the further easing of lockdown regulations and presence of the B.1.617.2 lineage. If prevalence rises in the coming weeks, policy-makers will need to assess the possible impact on hospitalisations and deaths. In addition, consideration should be given to other health and economic impacts if increased levels of community transmission occur.

scholarly journals Mass transfer and stellar wind effects in the eclipsing binary RT Andromedae

1981 ◽  
Vol 59 ◽  
pp. 491-494
Author(s):  
G.A. Bakos ◽  
J. Tremko
Keyword(s):  
Mass Transfer ◽  
Light Curve ◽  
Spectral Type ◽  
Orbital Period ◽  
Stellar Wind ◽  
Mass Ratio ◽  
Eclipsing Binary ◽  
Short Period ◽  
Photometric Elements ◽  
Number Of Authors

In recent years the short period eclipsing binary RT And has been studied extensively by a number of authors. From photo electric observations the light curve and the photometric elements were derived by Dean (1974) and Mancuso et al. (1979). The geometric dimensions of the binary confirm that the system is detached consisting of two stars of spectral type F8 V and KO V. The mass ratio is 0.66. In spite of this classification, effects appearing among semidetached systems have been observed, namely, variations of the amplitude and the shape of the light curve and changes of the length of the orbital period.

scholarly journals Orbital Period Modulation in SW Cygni

2007 ◽  
Vol 24 (2) ◽  
pp. 61-68 ◽  
Author(s):  
Davood Manzoori
Keyword(s):  
Mass Transfer ◽  
Fourier Analysis ◽  
Orbital Period ◽  
Transfer Rate ◽  
Mass Transfer Rate ◽  
Period Change ◽  
Rate Of Change ◽  
Relative Mass ◽  
Eclipsing Binary ◽  
Period Variations

AbstractThe O–C curve of the Algol-type eclipsing binary SW Cyg was analyzed using the Kalimeris method. The observed period variations with time, the P(E) function and its rate of change dP/dE, were calculated. The plots of O–C values as well as of P(E) and dP/dE against ephemeris (E) all show rather regular period variations in this system. To reveal any cyclic period variations, the P(E) function was subjected to Fourier analysis. A cyclic period change of average ≈27.8-yr duration was obtained. Also a relative mass transfer rate of Δm/m = −1.1 × 10−9 yr−1 was estimated. Finally the existence of a third companion is suggested, and possible causes of period variations in the system are discussed.

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