Observations and Light Curve Solutions of Ultrashort-Period Eclipsing Binaries

AbstractPhotometric observations in V and I bands and low-dispersion spectra of 10 ultrashort-period binaries (NSVS 2175434, NSVS 2607629, NSVS 5038135, NSVS 8040227, NSVS 9747584, NSVS 4876238, ASAS 071829-0336.7, SWASP 074658.62+224448.5, NSVS 2729229, NSVS 10632802) are presented. One of them, NSVS 2729229, is newly discovered target. The results from modelling and analysis of our observations revealed that (i) eight targets have overcontact configurations with considerable fill-out factor (up to 0.5), while NSVS 4876238 and ASAS 0718-03 have almost contact configurations; (ii) NSVS 4876238 is rare ultrashort-period binary of detached type; (iii) all stellar components are late dwarfs; (iv) the temperature difference of the components of each target does not exceed 400 K; (v) NSVS 2175434 and SWASP 074658.62 + 224448.5 exhibit total eclipses and their parameters could be assumed as well determined; (v) NSVS 2729229 shows emission in the Hα line. Masses, radii, and luminosities of the stellar components were estimated by the empirical relation ‘period, orbital axis’ for short- and ultrashort-period binaries. We found linear relations mass–luminosity and mass–radius for the stellar components of our targets.

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Global parameters of the newly-discovered W UMa stars WISEJ004327.7+722407 and WISEJ234557.8+510456

Serbian Astronomical Journal ◽

10.2298/saj2000019k ◽

2020 ◽

pp. 19-23

Author(s):

D. Kjurkchieva ◽

S. Ibryamov

Keyword(s):

Light Curve ◽

Spectral Type ◽

Eclipsing Binaries ◽

Light Levels ◽

Photometric Observations ◽

Global Parameters

Photometric observations in g' and i' bands of the newly-discovered W UMa stars WISEJ004327.7+722407 and WISEJ234557.8+510456 are presented. The two targets are with shallow-contact configurations and their components are of G{K spectral type. We found that WISEJ004327.7+722407 is of A subtype while WISEJ234557.8+510456 is of W subtype. The different light levels at the quadratures were reproduced by cool spots on the bigger components. The procedure for calculation of the global parameters of eclipsing binaries by light curve solutions and GAIA distances was refined for stars with deep eclipses. The obtained global parameters reveal that at least one of the components of WISEJ004327.7+722407 and WISEJ234557.8+510456 is oversized, overluminous and too hot compared with an MS star with the same mass.

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Observations and light curve solutions of the eclipsing binaries KR Lyn, CSS J110212+244412, NSVS 4917488 and NSVS 7336024

Serbian Astronomical Journal ◽

10.2298/saj170921001k ◽

2018 ◽

pp. 21-27 ◽

Cited By ~ 1

Author(s):

D. Kjurkchieva ◽

V.A. Popov ◽

J. Eneva ◽

N. Petrov

Keyword(s):

Light Curve ◽

Eclipsing Binaries ◽

Type Star ◽

Eclipsing Stars ◽

Photometric Observations ◽

Short Period

We present photometric observations in Sloan filters g?, i? of the short-period eclipsing stars KR Lyn, CSS J110212+244412, NSVS 4917488 and NSVS 7336024. The light curve solutions revealed that all targets are overcontact binaries whose components are G and K stars. Their temperature differences do not exceed 300 K but they differ considerably in size and mass. NSVS 4917488 and NSVS 7336024 reveal total eclipses and their parameters can be considered as well-determined. We found that KR Lyn, NSVS 4917488 and NSVS 7336024 are of W-subtype while CSS J110212+244412 is A-subtype W UMa-type star.

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FOUR NEW γ DORADUS VARIABLES IN ECLIPSING BINARIES: REVISED PULSATION PERIOD RELATIONS

Revista Mexicana de Astronomía y Astrofísica ◽

10.22201/ia.01851101p.2020.56.02.12 ◽

2020 ◽

Vol 56 (2) ◽

pp. 321-330

Author(s):

O. Özdarcan ◽

Ö. Çakirli

Keyword(s):

Light Curve ◽

Orbital Period ◽

Eclipsing Binaries ◽

The Other ◽

Physical Parameters ◽

Logarithmic Scale ◽

Pulsation Period ◽

Eclipsing Binary ◽

Linear Relations ◽

Best Fitting

We present photometric light curve modelling of four Kepler eclipsing binaries KIC 2720354, KIC 10063044, KIC 11724091 and KIC 8565912. The modelling results show that KIC 10063044 is a semi-detached eclipsing binary, while the other systems are detached eclipsing binaries. Estimated physical parameters of these systems and residuals from the best-fitting light curve models strongly indicate γ Dor type pulsations on the primary components of the target systems. Evaluating the relations between pulsation period (Ppuls) and orbital period (Porb), the force exerted to per gram on the surface of the pulsating star (F/Mpuls) and the fractional radius of the pulsating star (r), we find that linear relations on a logarithmic scale still exist, but with a smaller slope than reported in previous studies.

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Observations and light curve solutions of the eclipsing binaries USNO-B1.0 1395-0370184 and USNO-B1.0 1395-0370731

Serbian Astronomical Journal ◽

10.2298/saj160328005k ◽

2016 ◽

pp. 27-32 ◽

Cited By ~ 1

Author(s):

D. Kjurkchieva ◽

V.A. Popov ◽

D. Vasileva ◽

N. Petrov

Keyword(s):

Light Curve ◽

Eclipsing Binaries ◽

Eclipsing Stars ◽

System P ◽

Photometric Observations ◽

Short Period ◽

Orbital Periods ◽

Period System

We present follow-up photometric observations in Sloan filters g', i' of the newly discovered eclipsing stars USNO-B1.0 1395-0370184 and USNO-B1.0 1395-0370731. Our data revealed that their orbital periods are considerably bigger than the previous values. This result changed the classification of USNO-B1.0 1395-0370184 from ultrashort-period binary (P=0.197 d) to short-period system (P=0.251 d). The light curve solutions of our observations revealed that USNOB1.0 1395-0370184 and USNO-B1.0 1395-0370731 are overcontact binaries in which components are K dwarfs, close in masses and radii. The light curve distortions were reproduced by cool spots with angular radius of around 20?.

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Observations and light curve solutions of four ultrashort-period binaries

Serbian Astronomical Journal ◽

10.2298/saj150914001k ◽

2016 ◽

pp. 21-26 ◽

Cited By ~ 5

Author(s):

D. Kjurkchieva ◽

V. Popov ◽

D. Vasileva ◽

N. Petrov

Keyword(s):

Light Curve ◽

Eclipsing Binaries ◽

M Dwarfs ◽

Upper Limit ◽

Contact Binaries ◽

Orbital Periods

The paper presents light curve solutions of our observations of four new ultrashort-period eclipsing binaries with MS components. Two of them have periods almost at the upper limit (0.22 days) of the ultrashort-period binaries, while the periods of around 0.18 days of CSS J171508.5+350658 and CSS J214633.8+120016 are amongst the shortest known orbital periods. CSS J171410.0+ 445850, CSS J214633.8+120016 and CSS J224326.0+154532 are over contact binaries with fill out factors around 0.25 while CSS J171508.5+350658 is a semidetached system. The two targets with shortest periods consist of M dwarfs.

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Early Blue Excess from the Type Ia Supernova 2017cbv

Proceedings of the International Astronomical Union ◽

10.1017/s1743921318002193 ◽

2017 ◽

Vol 14 (S339) ◽

pp. 47-49

Author(s):

G. Hosseinzadeh

Keyword(s):

Light Curve ◽

Standard Type ◽

Circumstellar Material ◽

Type Ia Supernova ◽

Unusual Distribution ◽

Photometric Observations ◽

Type Ia ◽

Optical Light Curve ◽

Ia Supernovae

AbstractThis paper presented very early, high-cadence photometric observations of the nearby Type Ia SN 2017cbv. The light-curve is unique in that during the first five days of observations it has a blue bump in the U, B, and g bands which is clearly resolved by virtue of our photometric cadence of 5.7 hr during that time span. We modelled the light-curve as the combination of an early shock of the supernova ejecta against a non-degenerate companion star plus a standard Type Ia supernova component. Our best-fit model suggested the presence of a subgiant star 56 R⊙ from the exploding white dwarf, although that number is highly model-dependent. While the model matches the optical light-curve well, it over-predicts the flux expected in the ultraviolet bands. That may indicate that the shock is not a blackbody, perhaps because of line blanketing in the UV. Alternatively, it could point to another physical explanation for the optical blue bump, such as interaction with circumstellar material or an unusual distribution of the element Ni. Early optical spectra of SN 2017cbv show strong carbon absorption as far as day –13 with respect to maximum light, suggesting that the progenitor system contained a significant amount of unburnt material. These results for SN 2017cbv illustrate the power of early discovery and intense follow-up of nearby supernovæ for resolving standing questions about the progenitor systems and explosion mechanisms of Type Ia supernovæ.

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A Comparison Between Binary Star Light Curves and Those of Possible Binary Asteroids

International Astronomical Union Colloquium ◽

10.1017/s0252921100088722 ◽

1984 ◽

Vol 80 ◽

pp. 387-392

Author(s):

H. J. Schober

Keyword(s):

Light Curve ◽

Binary Star ◽

Variable Stars ◽

Eclipsing Binaries ◽

Light Curves ◽

Binary Asteroids ◽

Binary Nature ◽

Rotation Rates ◽

Photoelectric Observations

AbstractSince about ten years coordinated programs of photoelectric observations of asteroids are carried out to derive rotation rates and light curves. Quite a number of those asteroids exhibit features in their light curves, with similar characteristics as variable stars and especially eclipsing binaries. This would allow also an interpretation that there might be an evidence for the binary nature of some asteroids, based on observational hints. A few examples are given and a list of indications for the possible binary nature of asteroids, based on their light curve features, is presented.

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Activity of (6478) Gault during 2019 January 13–March 28

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa1630 ◽

2020 ◽

Vol 496 (3) ◽

pp. 2636-2647

Author(s):

Oleksandra Ivanova ◽

Yuri Skorov ◽

Igor Luk'yanyk ◽

Dušan Tomko ◽

Marek Husárik ◽

...

Keyword(s):

Light Curve ◽

Broad Band ◽

The Body ◽

Rotational Period ◽

Photometric Observations

ABSTRACT We present the results of photometric observations of active asteroid (6478) Gault performed at heliocentric distances from 2.46 to 2.30 au and geocentric distances from 1.79 to 1.42 au between 2019 January 15 and March 28. Observations were carried out at the 2.5-m telescope of SAI MSU (Caucasian Mountain Observatory) on 2019 January 15 and at the 1.3 and 0.61-m telescopes (SPb) on 2019 February 6 and March 28, respectively. The direct images of the asteroid were obtained with the broad-band B, V, and R filters. Comet-like structures were detected at all observation dates. Colour maps were built and colour variations along the tail for the observation made on 2019 January 15 were analysed. The Afρ was calculated for the R filter, and the evaluated value varies from 47 to 32 cm for the period from 2019 January to the end of March. The rotational period of the body is estimated from the light curve by different methods and is about 1.79 h. Possible mechanisms of triggering Gault's activity are discussed.

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