J/A+A/666/A143 AD Leo RV and stellar activity indices (Kossakowski+, 2022)
The CARMENES search for exoplanets around M dwarfs.
Stable radial-velocity variations at the rotation period of AD Leonis.
A test case study of current limitations to treating stellar activity.
Kossakowski D., Kuerster M., Henning T., Trifonov T. Caballero J.A.,
Lafarga M., Bauer F.F., Stock S., Kemmer J., Jeffers S.V., Amado P.J. ,
Perez-Torres M., Bejar V.J.S., Cortes-Contreras M., Ribas I., Reiners A.,
Quirrenbach A., Aceituno J., Baroch D., Cifuentes C., Dreizler S.,
Hatzes A., Kaminski A., Montes D., Morales J. C., Pavlov A., Pena L.,
Perdelwitz V., Reffert S., Revilla D., Rodriguez Lopez C., Rosich A.,
Sadegi S., Sanz-Forcada J., Schoefer P., Schweitzer A., Zechmeister M.
<Astron. Astrophys. 666, A143 (2022)>
=2022A&A...666A.143K 2022A&A...666A.143K (SIMBAD/NED BibCode)
ADC_Keywords: Stars, double and multiple ; Stars, M-type ; Stars, dwarfs ;
Exoplanets ; Spectroscopy ; Radial velocities ; Optical
Keywords: techniques: radial velocities - stars: late-type -
stars: individual: AD Leo - stars: activity
Abstract:
A challenge with radial-velocity (RV) data is disentangling the origin
of signals either due to a planetary companion or to stellar activity.
Obtaining data over a large time span and wavelength range for this
reason is crucial, but can oftentimes be difficult to achieve. The
existence of a planetary companion has been proposed, as well as
contested, around the relatively bright, nearby M3.0V star AD Leo at
the same period as the stellar rotation of 2.23d.
We further investigate the nature of this signal for the flare star.
We introduce new CARMENES optical and near-IR RV data and an analysis
in combination with archival data taken by HIRES and HARPS, along with
more recent data taken by HARPS-N, GIANO-B, and HPF. Additionally, we
address the confusion concerning the binarity of AD Leo.
We consider possible correlations that the RVs may have with an
assortment of stellar activity indicators accessible with CARMENES. We
additionally performed a variety of modeling techniques considering
all RV data using the Bayesian log evidence to determine whether a
Keplerian planetary model, a red-noise quasi-periodic stellar activity
model using a Gaussian process, or a mixed model would explain the
observed data best. In addition, we take a closer look at spectral
lines potentially associated with stellar activity.
The CARMENES RV data agree with the previously reported periodicity of
2.23d, correlate with some activity indicators, and exhibit
chromaticity. However, when considering the entire, extensive RV data
set, we find that a mixed model composed of a stable and a variable
component performs best. Moreover, when recomputing the RVs using only
spectral lines insensitive to activity, there appears to be some
residual power at the period of interest. We therefore conclude that
it is not possible to determinedly prove that there is no planet
orbiting in synchronization with the stellar rotation given our data,
current tools, machinery, and knowledge of how stellar activity
affects RVs. We do rule out planets more massive than 27M⊕
(=0.084M{Jup}). In addition, we rule out any binary companion around
AD Leo with Msini greater than 3-6M{Jup} on orbital periods <14yr.
Description:
Radial-velocity and stellar activity indicator time series of AD Leo
for the following data sets:
CARMENES VIS, CARMENES NIR, HARPS-S, HIRES
These were all processed with serval (Zechmeister et al.,
2018A&A...609A..12Z 2018A&A...609A..12Z).
The other data sets used in this work were adopted from the original
papers:
GIARPS -> Carleo et al., 2020A&A...638A...5C 2020A&A...638A...5C, Cat. J/A+A/638/A5
(consists of HARPS-N and GIANO-B data
HPF -> Roberston et al., 2020ApJ...897..125R 2020ApJ...897..125R
Objects:
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RA (2000) DE Designation(s)
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10 19 36.28 +19 52 12.0 AD Leo = BD+20 2465 = GJ 388
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
carvs1.dat 55 26 CARMENES-VIS radial velocities of AD Leo (season 1)
(table A2)
carvs2.dat 55 20 CARMENES-VIS radial velocities of AD Leo (season 2)
(table A2)
carns1.dat 55 26 CARMENES-NIR radial velocities of AD Leo (season 1)
(table A3)
carns2.dat 55 20 CARMENES-NIR radial velocities of AD Leo (season 2)
(table A3)
harps.dat 42 47 HARPS-S radial velocities of AD Leo (table A4)
hires.dat 45 43 HIRES radial velocities of AD Leo (table A5)
carvs1-a.dat 364 26 CARMENES-VIS stellar activity indicators of AD Leo
(season 1) (Fig. C1)
carvs2-a.dat 364 20 CARMENES-VIS stellar activity indicators of AD Leo
(season 2) (Fig. C1)
carns1-a.dat 149 26 CARMENES-NIR stellar activity indicators of AD Leo
(season 1) (Fig. C2)
carns2-a.dat 149 20 CARMENES-NIR stellar activity indicators of AD Leo
(season 2) (Fig. C3)
harps-a.dat 77 47 HARPS-S stellar activity indicators of AD Leo
(Fig. C3)
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See also:
J/A+A/637/A13 : AD Leo high resolution spectra (Muheki+, 2020)
J/A+A/638/A5 : HD 285507 and AD Leo light and velocity curves (Carleo+, 2020)
Byte-by-byte Description of file: car[nv]s[12].dat harps.dat hires.dat
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Bytes Format Units Label Explanations
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1- 13 F13.5 d BJD Barycentric Julian date
15- 35 F21.17 m/s RV Radial velocity
37- 55 F19.16 m/s e_RV Radial velocity uncertainty
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Byte-by-byte Description of file: carvs1-a.dat carvs2-a.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 13 F13.5 d BJD Barycentric Julian date
15- 29 F15.10 --- CRX Chromatic index (in m/s/Np unit)
31- 43 F13.10 --- e_CRX Chromatic index uncertainty (in m/s/Np unit)
45- 59 F15.11 1000m2/s2 dLW Differential line width
61- 74 F14.11 1000m2/s2 e_dLW Differential line width uncertainty
76- 89 F14.12 --- CAIRT1 CaII-IRT1 index (8498.02) (-15,15)km/s
91-106 F16.14 --- e_CAIRT1 CaII-IRT1 index uncertainty
108-121 F14.12 --- CAIRT2 CaII-IRT2 index (8542.09) (-15,15)km/s
123-138 F16.14 --- e_CAIRT2 CaII-IRT2 index uncertainty
140-153 F14.12 --- CAIRT3 CaII-IRT3 index (8662.14) (-15,15)km/s
155-170 F16.14 --- e_CAIRT3 CaII-IRT3 index uncertainty
172-185 F14.12 --- Halpha Hα index
186-201 F16.14 --- e_Halpha Hα index uncertainty
203-212 F10.8 --- TiO7050 Photospheric TiO absorption band index
at 7050Å
214-234 F21.19 --- e_TiO7050 Photospheric TiO absorption band index
at 7050Å uncertainty
236-245 F10.8 --- TiO8430 Photospheric TiO absorption band index
at 8430Å index
247-267 F21.19 --- e_TiO8430 Photospheric TiO absorption band index
at 8430Å index uncertainty
269-278 F10.8 --- TiO8860 Photospheric TiO absorption band index
at 8860Å index
280-300 F21.19 --- e_TiO8860 Photospheric TiO absorption band index
at 8860Å index uncertainty
302-310 F9.5 m/s BIS CCF bisector velocity span
312-319 F8.5 m/s e_BIS CCF Bisector velocity span uncertainty
321-330 F10.8 % CTR CCF contrast
332-341 F10.8 % e_CTR CCF contrast uncertainty
343-353 F11.8 km/s FWHM CCF full width at half maximum
355-364 F10.8 km/s e_FWHM CCF full width at half maximum uncertainty
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Byte-by-byte Description of file: carns1-a.dat carns2-a.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 13 F13.5 d BJD Barycentric Julian date
15- 31 F17.12 --- CRX Chromatic index (in m/s/Np unit)
34- 47 F14.10 --- e_CRX Chromatic index uncertainty (in m/s/Np unit)
49- 65 F17.12 1000m2/s2 dLW Differential line width
67- 80 F14.11 1000m2/s2 e_dLW Differential line width uncertainty
82- 91 F10.5 m/s BIS CCF bisector velocity span
94-103 F10.5 m/s e_BIS CCF Bisector velocity span uncertainty
105-115 F11.8 % CTR CCF contrast
117-126 F10.8 % e_CTR CCF contrast uncertainty
128-138 F11.8 km/s FWHM CCF full width at half maximum
140-149 F10.8 km/s e_FWHM CCF full width at half maximum uncertainty
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Byte-by-byte Description of file: harps-a.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 13 F13.5 d BJD Barycentric Julian date
15- 21 F7.3 --- CRX Chromatic index (in m/s/Np unit)
23- 28 F6.3 --- e_CRX Chromatic index uncertainty (in m/s/Np unit)
30- 36 F7.3 1000m2/s2 dLW Differential line width
38- 42 F5.3 1000m2/s2 e_dLW Differential line width uncertainty
44- 49 F6.3 m/s BIS CCF bisector velocity span
51- 55 F5.3 m/s e_BIS CCF Bisector velocity span uncertainty
57- 61 F5.3 % CTR CCF contrast
63- 66 F4.2 % e_CTR CCF contrast uncertainty
68- 73 F6.3 km/s FWHM CCF full width at half maximum
75- 77 F3.1 km/s e_FWHM CCF full width at half maximum uncertainty
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Acknowledgements:
Diana Kossakowski, diana.kossakowski(at)gmail.com
References:
Zechmeister et al., 2018A&A...609A..12Z 2018A&A...609A..12Z, Spectrum radial velocity analyser
(SERVAL). High-precision radial velocities and two alternative spectral
indicators
Carleo et al., 2020A&A...638A...5C 2020A&A...638A...5C, The GAPS Programme at TNG. XXI. A
GIARPS case study of known young planetary candidates: confirmation of
HD 285507 b and refutation of AD Leonis b
Robertson et al., 2020ApJ...897..125R 2020ApJ...897..125R, Persistent Starspot Signals on M
Dwarfs: Multiwavelength Doppler Observations with the Habitable-zone Planet
Finder and Keck/HIRES
(End) Diana Kossakowski [MPIA, Germany], Patricia Vannier [CDS] 09-Sep-2022