Discovery of an X-Ray-Emitting Contact Binary System 2mass J11201034−2201340

Hu, Chin-Ping; Yang, T. C.; Chou, Yi; Liu, Lei; Qian, S.‐B.; Hui, C. Y.; Kong, Albert; Lin, L.; Tam, P. H. T.; Li, K. L.; Ngeow, Chow-Choong; Chen, W. P.; Ip, Wing-Huen

doi:10.3847/0004-6256/151/6/170

Cited by 5 publications

(5 citation statements)

References 25 publications

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“…Systems of late spectral type generally belong to the W-subtype of W UMa contact binaries, but there are some exceptions that belong to the A-subtype as 2MASS J11201034-2201340 (Hu et al 2016), ES Cep (Zhu et al 2014), NSV 395 (Samec et al 2016), and AP UMi (Awadalla et al 2016).…”

Section: Photometric Solution With the W-d Methodsmentioning

confidence: 99%

Photometric Analysis of Two K Spectral Type Contact Binary Systems

Barani¹,

Martignoni²,

Acerbi³

et al. 2022

RMxAA

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The first analysis of the light curves of contact binaries ROTSE J135349.8+305205 (CB1) and 1SWASP J150957.5-115308 (CB2) using the Wilson-Devinney code is presented. Both binary systems are of the A-subtype with a shallow fill-out (20.8% and 15.8% respectively) and a difference in temperatures between the components of < 200 K. A mass-ratio of 0.302 is found for CB1, while for CB2 the interesting value of 0.904 is found. The short periods, 0.246 d for CB1 and 0.229 d for CB2, and their spectral type K suggests that these systems are near the shortest period limit. The absolute elements are estimated using GAIA parallaxes. CB2 is found to be at the beginning of its evolution, while CB1 will approach the final evolutionary stage. The sum of the component masses of CB1 is 0.813 M☉, below the mass limit of 1.0 − 1.2 M☉ assumed for the known contact binary stars.

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Section: Photometric Solution With the W-d Methodsmentioning

confidence: 99%

Photometric Analysis of Two K Spectral Type Contact Binary Systems

Barani¹,

Martignoni²,

Acerbi³

et al. 2022

RMxAA

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“…The fitting of asymmetry and O'Connell effect in the optical light curves suggests the presence of spot. The X-ray emission may be caused by the chromosphere and corona activity (Huenemoerder et al 2006;Kandulapati et al 2015;Hu et al 2016). The location, size, and temperature of the spot change with time.…”

Section: The X-ray Emissionmentioning

confidence: 99%

“…Their X-ray intensities are related to their orbital periods and spectral types (Stȩpień et al 2001;Chen et al 2006). The studies of 2MASS J11201034-2201340 (Hu et al 2016) and VW Cep (Huenemoerder et al 2006) indicate that the X-ray light curves do not show obvious occultation or modulation as optical light curves do. The investigation of VW Cep and YY Eri (Vilhu & Maceroni 2007) suggests that in a UMa binary system, the massive component dominates the magnetic activity.…”

Section: Introductionmentioning

confidence: 99%

“…Many W UMa-type binaries are X-ray emitters. Some of their fundamental features, including high chromospheric and coronal activity (Huenemoerder et al 2006;Kandulapati et al 2015;Hu et al 2016), and synchronous fast-rotation common envelopes (Gondoin 2004;Chen et al 2006), are believed to be the origin of the X-ray emission. Their X-ray intensities are related to their orbital periods and spectral types (Stȩpień et al 2001;Chen et al 2006).…”

Section: Introductionmentioning

confidence: 99%

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An Optical and X-Ray Study of the Contact Binary, BH Cassiopeiae

Liu

Esamdin

et al. 2019

PASP

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We present the revised and high-quality CCD time series observations in 2017 and 2018 of the W UMa-type contact binary BHCas. The combination of our new determinations of minimum times and those collected from the literatures reveal a long-term period increase with a rate of dP/dt=+3.27×10 −7 day yr −1 , which can be accounted for by angular momentum transfer as the less-massive component loses its mass to the more massive one. One cyclical oscillation (A′=0.00300 day and P′=20.09 yr) superimposed on the long-term period increase tendency is attributed to one additional object that orbits BH Cas. The low-resolution spectra of this source are observed at phase ∼0.0 and ∼0.5 in 2018 and 2019, and the spectral types are identified as K3V±1 and G8V±2. According to the luminosity contributions and spectra at these phases, the spectral type of the primary star is close to K3V±1. We infer a cool spot on the hotter and less-massive component to fit the asymmetry of light curves. In addition, changes in the location, temperature, and area of spots on the secondary star in different observations may indicate that the magnetic field activity of the secondary is more active than that of the primary. Such strong spot activities and optical flare are both detected at the same time from a W UMa-type star for the first time. With the XMM-Newton observations taken in 2003 and 2012, the X-ray light curve is obtained and the X-ray spectra can be well described with a blackbody or a bremsstrahlung model. The soft X-ray luminosity of BH Cas is estimated as (8.8-9.7)×10 30 erg s −1 .

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“…In contrast, the coronae in TX Cnc have uniformly distributed X-ray emitting regions with both components being equally active and having the same brightness per surface area. Two other contact binaries, BH Cas (Liu et al 2019) and 2MASS J11201034-2201340 (Hu et al 2016) were serendipitously detected in unrelated X-ray observations. For both objects no eclipses or significant variability were found, which may, however, be due to the low signal-to-noise ratio of the X-ray light curves.…”

Section: Introductionmentioning

confidence: 97%

X-Ray and UV Observations of the Contact Binary KIC 9832227

Pandel

Molnar

2023

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We investigate the X-ray and UV emission from the contact binary star KIC 9832227, which was observed with XMM-Newton for one orbital cycle. The binary is detected with an average X-ray luminosity of 3.4 × 1030 erg s−1. The X-ray emission is restricted to energies below 3 keV and originates from a multitemperature plasma with temperatures up to 1 keV. The X-ray spectrum has at least two distinct components, a cooler, mostly steady component, and a hotter component exhibiting significant variability. The variable X-ray emission appears to originate from a compact flare near the contact region between the two stars that is being eclipsed by the secondary. We analyze the eclipse profile to constrain the location, size, and density of the flaring region. The remaining X-ray emission is not eclipsed and could originate from the polar region on the primary star or an extended corona. The UV emission exhibits the same nearly sinusoidal modulation at half the orbital period that is observed at longer wavelengths. The primary and secondary eclipses have slightly different depths, which is generally attributed to starspot activity. Using simulations of the UV light curve with stellar atmosphere models, we deduce the presence of a starspot near the polar region of the primary, and we determine the time of primary eclipse.

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Discovery of an X-Ray-Emitting Contact Binary System 2mass J11201034−2201340

Cited by 5 publications

References 25 publications

Photometric Analysis of Two K Spectral Type Contact Binary Systems

Photometric Analysis of Two K Spectral Type Contact Binary Systems

An Optical and X-Ray Study of the Contact Binary, BH Cassiopeiae

X-Ray and UV Observations of the Contact Binary KIC 9832227

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