J/AJ/155/192 Radial velocities & photometry of AD Leonis & GJ 674 (Tuomi+, 2018)
AD Leonis: radial velocity signal of stellar rotation or spin-orbit resonance?
Tuomi M., Jones H.R.A., Barnes J.R., Anglada-Escude G., Butler R.P.,
Kiraga M., Vogt S.S.
<Astron. J., 155, 192-192 (2018)>
=2018AJ....155..192T 2018AJ....155..192T (SIMBAD/NED BibCode)
ADC_Keywords: Stars, dwarfs ; Stars, M-type ; Radial velocities ;
Photometry, UBV
Keywords: methods: numerical - methods: statistical -
techniques: radial velocities
Abstract:
AD Leonis is a nearby magnetically active M dwarf. We find Doppler
variability with a period of 2.23 days, as well as photometric signals:
(1) a short-period signal, which is similar to the radial velocity signal,
albeit with considerable variability; and (2) a long-term activity cycle
of 4070±120 days. We examine the short-term photometric signal in
the available All-Sky Automated Survey and Microvariability and
Oscillations of STars (MOST) photometry and find that the signal is not
consistently present and varies considerably as a function of time.
This signal undergoes a phase change of roughly 0.8 rad when considering
the first and second halves of the MOST data set, which are separated
in median time by 3.38 days. In contrast, the Doppler signal is stable
in the combined High-Accuracy Radial velocity Planet Searcher and High
Resolution Echelle Spectrometer radial velocities for over 4700 days and
does not appear to vary in time in amplitude, phase, period, or as a
function of extracted wavelength. We consider a variety of starspot
scenarios and find it challenging to simultaneously explain the rapidly
varying photometric signal and the stable radial velocity signal as being
caused by starspots corotating on the stellar surface. This suggests
that the origin of the Doppler periodicity might be the gravitational tug
of a planet orbiting the star in spin-orbit resonance. For such a scenario
and no spin-orbit misalignment, the measured vsini indicates an inclination
angle of 15.5±2.5° and a planetary companion mass of
0.237±0.047 MJup.
Description:
Spectroscopic data of AD Leo were obtained from two sources. We
downloaded the publicly available data products of HARPS (Mayor et al.
2003Msngr.114...20M 2003Msngr.114...20M) from the European Southern Observatory archive
and processed them with the TERRA algorithms of Anglada-Escude & Butler
(2012, J/ApJS/200/15). As a result, we obtained a set of 47 radial
velocities with a baseline of 3811 days and root-mean-square (rms)
estimate of 22.59 m/s.
To study the photometric variability of AD Leo, we obtained ASAS
(Pojmanski 1997AcA....47..467P 1997AcA....47..467P; 2002, Cat. II/264) V-band photometry data
(http://www.astrouw.edu.pl/asas) from the ASAS-North (ASAS-N) and
ASAS-South (ASAS-S) telescopes. We only selected the "Grade A" data
from the set, removed all 5σ outliers, and obtained sets of 316 and
319 photometric measurements with baselines of 2344 and 2299 days,
respectively.
Objects:
-----------------------------------------------------
RA (ICRS) DE Designation(s)
-----------------------------------------------------
10 19 36.28 +19 52 12.0 AD Leonis = BD+20 2465
17 28 39.95 -46 53 42.7 GJ 674 = CD-46 11540
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 46 47 HARPS data of AD Leo
table4.dat 55 47 Example of HARPS radial velocity of AD Leo for
all 72 individual orders vi, i=1, ..., 72
table5.dat 46 64 Example of HARPS data of GJ 674
table6.dat 55 64 Example of HARPS radial velocity of GJ 674 for
all 72 individual orders vi, i=1, ..., 72
table7.dat 15 64 Example of ASAS-N photometry of AD Leo
table8.dat 15 64 Example of ASAS-S photometry of AD Leo
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See also:
II/264 : ASAS Variable Stars in Southern hemisphere
(Pojmanski+, 2002-2005)
J/A+A/474/293 : Radial velocities of GJ 674 (Bonfils+, 2007)
J/MNRAS/390/567 : Magnetic field and velocity of mid M dwarfs (Morin+, 2008)
J/ApJS/200/15 : HARPS-TERRA project. I. (Anglada-Escude+, 2012)
http://www.astrouw.edu.pl/asas : The All Sky Automated Survey (ASAS) website
Byte-by-byte Description of file: table3.dat table5.dat
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Bytes Format Units Label Explanations
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1- 12 F12.4 d JD Julian Date
14- 19 F6.2 m/s RV [-38.61/42.94] Radial velocity
21- 24 F4.2 m/s e_RV [0.32/2.07] Uncertainty in RV
26- 31 F6.2 m/s BIS [-18.92/0.29] Bisector span
33- 39 F7.2 m/s FWHM [3018.96/3547.48] Full width at half maximum
41- 46 F6.3 m/s Sindex [1.006/11.415] S-index measuring the emission
of Ca II H & K lines
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Byte-by-byte Description of file: table4.dat table6.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 F9.4 d JD [2986.8579/6797.5118] Julian Date (JD-2450000)
11- 17 F7.2 m/s RV1 [-588.71/1176.8] Radial velocity for the
first dataset
19- 24 F6.2 m/s e_RV1 [51.51/321.81] Uncertainty in RV1
26- 33 F8.2 m/s RV2 [-1694.13/1210.13] Radial velocity for the
second dataset
35- 40 F6.2 m/s e_RV2 [58.77/286.01] Uncertainty in RV2
42- 48 F7.2 m/s RV3 [-631.43/1749.74] Radial velocity for the
third dataset
50- 55 F6.2 m/s e_RV3 [44.38/296.29] Uncertainty in RV3
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Byte-by-byte Description of file: table7.dat table8.dat
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Bytes Format Units Label Explanations
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1- 10 F10.2 d JD Julian Date
12- 15 I4 mag Vmag [9245/9391] ASAS V band magnitude
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History:
From electronic version of the journal
(End) Tiphaine Pouvreau [CDS] 28-Nov-2018