J/A+A/645/L6 zet01 Ret and zet02 activity indexes (Flores+, 2021)
Detecting prolonged activity minima in binary stars.
The case of ζ2 Reticuli.
Flores M., Jaque Arancibia M., Ibanez Bustos R.V., Buccino A.P.,
Yana Galarza J., Nunez N.E., Miquelarena P., Alacoria J., Saffe C.,
Mauas P.J.D.
<Astron. Astrophys. 645, L6 (2021)>
=2021A&A...645L...6F 2021A&A...645L...6F (SIMBAD/NED BibCode)
ADC_Keywords: Stars, G-type ; Binaries, orbits ; Spectroscopy
Keywords: stars: activity - binaries: general - Sun: chromospheres -
stars: individual: zet01 Ret - stars: individual: zet02 Ret
Abstract:
We explore if the star zet02 Ret, which belongs to a binary system, is
in (or going to) a state similar to the MM. To do so, we have
collected more than 430 spectra acquired between 2000 and 2019 with
the HARPS, REOSC, UVES, and FEROS spectrographs. We performed a
detailed long-term activity study of both components using the Mount
Wilson index, which is obtained from the Ca II H&K lines. To search
for signs of an activity cycle, we analyzed the resulting time-series
with the Generalized Lomb-Scargle and CLEAN periodograms. Our
spectroscopic analysis shows a high activity level for zet01 Ret and a
significant decrease in the magnetic activity cycle amplitude of
zet02 Ret. By analogy with the scenario that proposes a weak solar
cycle during the MM, we suggest that activity signatures showed by
zet02 Ret, i.e., a very low activity level when compared to its
stellar companion, a notably decreasing amplitude (∼47%), and a cyclic
behaviour, are possible evidence that this star could be in a MM
state. It is, to our knowledge, the first MM candidate star detected
through a highly discrepant activity behaviour in a binary system.
Description:
Observational data and derived Mount Wilson indexes for zet Ret. For
each component, observing date, instrument, observing program, and
derived S-index for each star are given.
Objects:
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RA (2000) DE Designation(s)
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03 17 46.16 -62 34 31.2 HD 20766 = * zet01 Ret
03 18 12.82 -62 30 22.9 HD 20807 = * zet02 Ret
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 90 352 Observational data and derived Mount Wilson
indexes for zet01 Ret and zet02 Ret
list.dat 95 14 List of HD 20766 (zet01 Ret) spectra
fits/* . 14 Individual fits spectra
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See also:
J/A+A/588/A81 : Line list and abundances of the binary zet2 Ret (Saffe+, 2016)
J/A+A/591/A34 : Chemical abundances of zeta Reticuly (Adibekyan+, 2016)
J/A+A/614/A138 : HD 80606/80607 equivalent widths (Lui+, 2018)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 10 A10 "date" ObsDate1 ? Observing date (zet 01 Ret)
12- 18 F7.2 d JD1 ? Julian day (zet 01 Ret)
20- 24 A5 --- Inst1 Instrument (zet 01 Ret)
26- 38 A13 --- ObsProg1 ID programs (zet 01 Ret)
40- 44 F5.3 --- SMW1 ? Mount Wilson index (zet 01 Ret)
46- 55 A10 "date" ObsDate2 Observing date (zet 02 Ret)
57- 63 F7.2 d JD2 Julian day (zet 02 Ret)
65- 69 A5 --- Inst2 Instrument (zet 02 Ret)
71- 84 A14 --- ObsProg2 ID programs (zet 02 Ret)
86- 90 F5.3 --- SMW2 Mount Wilson index (zet 02 Ret)
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Byte-by-byte Description of file: list.dat
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Bytes Format Units Label Explanations
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1- 5 I5 --- Nx Number of pixels along X-axis
7- 16 A10 "date" Obs.date Observation date
18- 24 F7.2 0.1nm blambda Lower value of wavelength interval
26- 32 F7.2 0.1nm Blambda Upper value of wavelength interval
34- 41 F8.6 0.1nm dlambda Wavelength resolution
43- 44 I2 Kibyte size Size of FITS file
46- 63 A18 --- FileName Name of FITS file, in subdirectory fits
65- 95 A31 --- Title Title of the FITS file
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Acknowledgements:
Matias Flores, matiasflorestrivigno(at)conicet.gov.ar
(End) Matias Flores [ICATE], Patricia Vannier [CDS] 16-Dec-2020