ASAS J083241+2332.4: A NEW EXTREME LOW MASS RATIO OVERCONTACT BINARY SYSTEM

ABSTRACT ZZ Piscis Austrinus (ZZ PsA) is a neglected bright southern contact binary system with maximum V magnitude of 9.26. We present the first multiband photometric analysis and find the system to be in deep contact (>95 per cent) with an extremely low mass ratio of 0.078. The primary has a mass of 1.213 M⊙ in keeping with its reported spectral class of F6. In order to determine if ZZ PsA is a merger candidate, we outline the current status regarding the instability mass ratio and develop new relationship linking the mass of the primary to the instability mass ratio of the system and the degree of contact. We find that ZZ PsA along with two other examples from the literature to be merger candidates while an additional three require further observations to be confirmed as potential merger candidates.

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Discovery of an M-type companion to the Herbig Ae Star V1787 Ori

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa3652 ◽

2020 ◽

Vol 501 (1) ◽

pp. 1243-1252

Author(s):

R Arun ◽

Blesson Mathew ◽

Sridharan Rengaswamy ◽

P Manoj ◽

Mayank Narang ◽

...

Keyword(s):

Binary System ◽

Adaptive Optics ◽

Spectral Type ◽

Template Matching ◽

Binary Systems ◽

Mass Ratio ◽

Wide Binary ◽

Star Forming ◽

Low Mass ◽

Low Mass Ratio

ABSTRACT The intermediate-mass Herbig Ae star V1787 Ori is a member of the L1641 star-forming region in the Orion A molecular cloud. We report the detection of an M-type companion to V1787 Ori at a projected separation of 6.66 arcsec (corresponding to 2577 au), from the analysis of VLT/NACO adaptive optics Ks-band image. Using astrometric data from Gaia DR2, we show that V1787 Ori A and B share similar distance (d ∼ 387 pc) and proper motion, indicating that they are physically associated. We estimate the spectral type of V1787 Ori B to be M5 ± 2 from colour–spectral type calibration tables and template matching using SpeX spectral library. By fitting PARSEC models in the Pan-STARRS colour–magnitude diagram, we find that V1787 Ori B has an age of 8.1$^{+1.7}_{-1.5}$ Myr and a mass of 0.39$^{+0.02}_{-0.05}$ M⊙. We show that V1787 Ori is a pre-main-sequence wide binary system with a mass ratio of 0.23. Such a low-mass ratio system is rarely identified in Herbig Ae/Be binary systems. We conclude this work with a discussion on possible mechanisms for the formation of V1787 Ori wide binary system.

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Photometric Analysis of Wide and Narrow Hα Band Observations of R Canis Majoris

Symposium - International Astronomical Union ◽

10.1017/s007418090012234x ◽

1992 ◽

Vol 151 ◽

pp. 303-306

Author(s):

M. Taghi Edalati ◽

Timothy Banks ◽

Edwin Budding

Keyword(s):

Hot Spot ◽

Optimal Estimate ◽

Mass Ratio ◽

Transfer Effects ◽

Photometric Analysis ◽

Index Variation ◽

Algol System ◽

Low Mass ◽

Low Mass Ratio ◽

Optimisation Technique

Wide and narrow Hα lightcurves of R CMa were analysed using Wilson-Devinney (WD) and Information Limit Optimisation Technique (ILOT) approaches. A range of mass ratios, tested by both methods, led to an optimal estimate of around 0.45, at variance with the spectroscopic value. The distortion on the light curve affects the modelling, and so, in a second fitting, this was represented by a ‘hot spot’, associated with mass transfer effects. A semi-detached configuration was then derived. This is supported by the form of the Hα index variation, which has also been modelled. Although thus appearing as a ‘classical Algol’ system, R CMa retains its inherent peculiarity of low mass ratio with low period, which cannot be reconciled with conservative evolution scenarios.

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A Common Origin for Low-mass Ratio Events Observed by LIGO and Virgo in the First Half of the Third Observing Run

The Astrophysical Journal ◽

10.3847/2041-8213/abd8c7 ◽

2021 ◽

Vol 907 (2) ◽

pp. L24

Author(s):

Mohammadtaher Safarzadeh ◽

Daniel Wysocki

Keyword(s):

Common Origin ◽

Mass Ratio ◽

The Third ◽

Low Mass ◽

Low Mass Ratio

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Two Contact Binaries with Mass Ratios Close to the Minimum Mass Ratio

The Astrophysical Journal ◽

10.3847/1538-4357/ac242f ◽

2021 ◽

Vol 922 (2) ◽

pp. 122

Author(s):

Kai Li ◽

Qi-Qi Xia ◽

Chun-Hwey Kim ◽

Shao-Ming Hu ◽

Di-Fu Guo ◽

...

Keyword(s):

Gyration Radius ◽

Mass Ratio ◽

Mass Ratios ◽

Contact Binaries ◽

Contact Binary ◽

Low Mass ◽

Ratio Limit ◽

Low Mass Ratio ◽

Diagram Analysis

Abstract The cutoff mass ratio is under debate for contact binaries. In this paper, we present the investigation of two contact binaries with mass ratios close to the low mass ratio limit. It is found that the mass ratios of VSX J082700.8+462850 (hereafter J082700) and 1SWASP J132829.37+555246.1 (hereafter J132829) are both less than 0.1 (q ∼ 0.055 for J082700 and q ∼ 0.089 for J132829). J082700 is a shallow contact binary with a contact degree of ∼19%, and J132829 is a deep contact system with a fill-out factor of ∼70%. The O − C diagram analysis indicated that the two systems manifested long-term period decreases. In addition, J082700 exhibits a cyclic modulation which is more likely resulting from the Applegate mechanism. In order to explore the properties of extremely low mass ratio contact binaries (ELMRCBs), we carried out a statistical analysis on contact binaries with mass ratios of q ≲ 0.1 and discovered that the values of J spin/J orb of three systems are greater than 1/3. Two possible explanations can interpret this phenomenon. One explanation is that some physical processes, unknown to date, are not considered when Hut presented the dynamic stability criterion. The other explanation is that the dimensionless gyration radius (k) should be smaller than the value we used (k 2 = 0.06). We also found that the formation of ELMRCBs possibly has two channels. The study of evolutionary states of ELMRCBs reveals that their evolutionary states are similar with those of normal W UMa contact binaries.

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