J/A+A/622/A153 GJ 4276 radial velocity curve (Nagel+, 2019)
The CARMENES search for exoplanets around M dwarfs.
The enigmatic planetary system of GJ 4276: one eccentric planet or two planets
in a 2:1 resonance?
Nagel E., Czesla S., Schmitt J.H.M.M., Dreizler S., Anglada-Escude G.,
Rodriguez E., Ribas I., Reiners A., Quirrenbach A., Amado P.J.,
Caballero J.A., Aceituno J., Bejar V.J.S., Cortes-Contreras M.,
Gonzalez-Cuesta L., Guenther E.W., Henning T., Jeffers S.V.,
Kaminski A., Kuerster M., Lafarga M., Lopez-Gonzalez M.J., Montes D.,
Morales J.C. Passegger V.M., Rodriguez-Lopez C., Schweitzer A.,
Zechmeister M.
<Astron. Astrophys. 622, A153 (2019)>
=2019A&A...622A.153N 2019A&A...622A.153N (SIMBAD/NED BibCode)
ADC_Keywords: Stars, double and multiple ; Exoplanets ; Radial velocities
Keywords: planetary systems - stars: individual: GJ 4276 - stars: low-mass -
methods: data analysis, observational - techniques: radial velocities
Abstract:
We report the detection of a Neptune-mass exoplanet around the M4.0
dwarf GJ 4276 (G 232-070) based on radial velocity (RV) observations
obtained with the CARMENES spectrograph. The RV variations of GJ 4276
are best explained by the presence of a planetary companion with a
minimum mass of mbsini∼16M☉ on a Pb=13.35-day orbit. The
analysis of the activity indicators and spectral diagnostics exclude
stellar induced RV perturbations and prove the planetary
interpretation of the RV signal. We show that a circular single-planet
solution can be excluded by means of a likelihood ratio test. Instead,
we find that the RV variations can either be explained by an eccentric
orbit or interpreted as a pair of planets on circular orbits near a
period ratio of 2:1. Although the eccentric single-planet solution is
slightly preferred, our statistical analysis indicates that none of
these two scenarios can be rejected with high confidence using the RV
time series obtained so far. Based on the eccentric interpretation, we
find that GJ 4276 b is the most eccentric (eb=0.37) exoplanet
around an M dwarf with such a short orbital period known today.
Description:
We analyzed radial velocity data from the CARMENES VIS channel. The
RVs are corrected for barycentric motion and secular acceleration. The
CARMENES measurements were taken in the context of the CARMENES search
for exoplanets around M dwarfs. The CARMENES instrument consists of
two channels: the VIS channel obtains spectra at a resolution of
R=94600 in the wavelength range 520-960nm, while the NIR channel
yields spectra of R=80400 covering 960-1710nm. Both channels are
calibrated in wavelength with hollow-cathode lamps and use
temperature- and pressure-stabilized Fabry-Perot etalons to
interpolate the wavelength solution and simultaneously monitor the
spectrograph drift during nightly operations (Bauer et al.,
2015A&A...581A.117B 2015A&A...581A.117B).
To determine the stellar rotation period, we obtained V band
photometry with the T150 telescope located at the Sierra Nevada
Observatory (SNO) in Spain.
Objects:
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RA (2000) DE Designation(s)
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22 25 17.07 +59 24 49.8 GJ 4276 = G 232-70
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
rv.dat 24 100 CARMENES radial-velocity time series for GJ 4276
(table C1)
sno.dat 23 1390 Sierra Nevada Observatory V-band photometric
time series of GJ 4276
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Byte-by-byte Description of file: rv.dat
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Bytes Format Units Label Explanations
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1- 11 F11.3 d BJD Barycentric Julian Date
13- 18 F6.2 m/s RV Radial velocity
21- 24 F4.2 m/s e_RV Radial velocity uncertainty
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Byte-by-byte Description of file: sno.dat
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Bytes Format Units Label Explanations
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1- 8 F8.3 d HJD Heliocentric Julian Date (HJD-2450000)
10- 16 F7.4 mag dVmag V-band magnitude normalized to zero
18- 23 F6.4 mag e_dVmag Uncertainty in V-band magnitude
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Acknowledgements:
Evangelos Nagel, Evangelos.Nagel(at)hs.uni-hamburg.de
(End) Evangelos Nagel [Univ. Hamburg], Patricia Vannier [CDS] 18-Dec-2018