J/A+A/692/L4 The lowest mass ratio contact binary (Li+, 2024)
Detection of the lowest mass ratio contact binary in the universe:
TYC 3801-1529-1.
Li K., Gao X., Guo D.-F., Gao D.-Y., Chen X., Wang L.-H., Xin Y.-X.,
Han Y.-X., Kim C.-H., Jeong M.-J.
<Astron. Astrophys. 692, L4 (2024)>
=2024A&A...692L...4L 2024A&A...692L...4L (SIMBAD/NED BibCode)
ADC_Keywords: Binaries, eclipsing ; Ephemerides ; Optical
Keywords: binaries: close - binaries: eclipsing - stars: evolution -
stars: individual: TYC 3801-1529-1
Abstract:
This paper presents the first analysis of the contact binary
TYC 3801-1529-1. We observed four sets of multiple bands complete
light curves and one set of radial velocity curve of the primary
component. Based on a simultaneous investigation of our observed and
TESS light curves and the radial velocity curve, we found that TYC
3801-1529-1 is an extremely low-mass-ratio, medium contact binary with
q=0.0356, with the contribution of the third light at a level of about
10%. Its mass ratio is lower than V1187 Her, making TYC 3801-1529-1
the lowest mass-ratio contact binary ever found in the universe. The
light curves observed in 2022 are asymmetric, which is aptly explained
by a hot spot on the primary component. A 16-year eclipse timings
analysis indicates a secular increase orbital period with a rate of
dp/dt=7.96(±0.35)*10-7d/yr. We studied the stability of this
target and identified that not only the value of Jspin/Jorb, but
also the mass ratio surpass the unstable boundary. Hence, TYC
3801-1529-1 presents a challenge to theoretical research and ought to
be considered a progenitor of a contact binary merger.
Description:
We performed the first photometric and spectroscopic study of a
totally eclipsing contact binary TYC 3801-1529-1.
The photometric observations of TYC 3801-1529-1 were carried out by
using the Weihai Observatory 1.0m Cassegrain telescope of Shandong
University (WHOT), the Weihai Observatory 50cm telescope (WH50), and
the 85 cm telescope at the Xinglong Station installed at the National
Astronomical Observatories (XL85) from 2021 to 2024. The PIXIS 2048B
CCD was installed on WHOT, resulting a field of view of 12'x12'; the
Dhyana 4040BSI sCMOS camera was equipped on WH50, resulting a field of
view of 36'x36'; the Andor DZ936 CCD was equipped on XL85, resulting a
field of view of 32'x32'.
Objects:
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RA (2000) DE Designation(s)
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08 41 18.84 +56 50 40.6 TYC 3801-1529-1 = TIC 445065429
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea3.dat 58 400 Eclipse timings of TYC 3801-1529-1
fig4a.gif 512 52088 An animation of Fig. 4A
fig3a/* . 22 CCF curves of TYC 3801-1529-1 in jpeg
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Byte-by-byte Description of file: tablea3.dat
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Bytes Format Units Label Explanations
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1- 13 F13.5 d BJD Barycentric Julian date of eclipse (TDB)
17- 23 F7.5 d e_BJD Uncertainty in BJD
27- 34 F8.1 --- E Cycle number
38- 45 F8.5 d O-C Observed - Calculated
49- 58 A10 --- Source Source
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Acknowledgements:
Kai Li, kaili(at)sdu.edu.cn
(End) Patricia Vannier [CDS] 18-Nov-2024