J/other/Nat/563.365 Barnard's star radial velocity curve (Ribas+, 2018)
A candidate super-Earth planet orbiting near the snow line of Barnard's star.
Ribas I., Tuomi M., Reiners A., Butler R.P., Morales J.C., Perger M.,
Dreizler S., Rodriguez-Lopez C., Gonzalez Hernandez J.I., Rosich A.,
Feng F., Trifonov T., Vogt S.S., Caballero J.A., Hatzes A., Herrero E.,
Jeffers S.V., Lafarga M., Murgas F., Nelson R.P., Rodriguez E.,
Strachan J.B.P., Tal-Or L., Teske J., Toledo-Padron B., Zechmeister M.,
Quirrenbach A., Amado P.J., Azzaro M., Bejar V.J.S., Barnes J.R.,
Berdinas Z.M., Burt J., Coleman G., Cortes-Contreras M., Crane J.,
Engle S.G., Guinan E.F., Haswell C.A., Henning T., Holden B., Jenkins J.,
Jones H.R.A., Kaminski A., Kiraga M., Kurster M., Lee M.H.,
Lopez-Gonzalez M.J., Montes D., Morin J., Ofir A., Palle E., Rebolo R.,
Reffert S., Schweitzer A., Seifert W., Shectman S.A., Staab D.,
Street R.A., Suarez Mascareno A., Tsapras Y., Wang S.X., Anglada-Escude G.
<Nature, 563, 365-368 (2018)>
=2018Natur.563..365R 2018Natur.563..365R (SIMBAD/NED BibCode)
ADC_Keywords: Stars, variable ; Radial velocities
Abstract:
Barnard's star is a red dwarf, and has the largest proper motion
(apparent motion across the sky) of all known stars. At a distance of
1.8 parsecs, it is the closest single star to the Sun; only the three
stars in the α Centauri system are closer. Barnard's star is also
among the least magnetically active red dwarfs known and has an
estimated age older than the Solar System. Its properties make it a
prime target for planetary searches; various techniques with different
sensitivity limits have been used previously, including
radial-velocity imaging, astrometry and direct imaging, but
all ultimately led to negative or null results. Here we combine
numerous measurements from high-precision radial-velocity instruments,
revealing the presence of a low-amplitude periodic signal with a
period of 233 days. Independent photometric and spectroscopic
monitoring, as well as an analysis of instrumental systematic effects,
suggest that this signal is best explained as arising from a planetary
companion. The candidate planet around Barnard's star is a cold
super-Earth, with a minimum mass of 3.2 times that of Earth, orbiting
near its snow line (the minimum distance from the star at which
volatile compounds could condense). The combination of all
radial-velocity datasets spanning 20 years of measurements
additionally reveals a long-term modulation that could arise from a
stellar magnetic-activity cycle or from a more distant planetary
object. Because of its proximity to the Sun, the candidate planet has
a maximum angular separation of 220 milliarcseconds from Barnard's
star, making it an excellent target for direct imaging and astrometric
observations in the future.
Description:
An early analysis of archival radial-velocity datasets of Barnard's
star up to 2015 indicated the presence of at least one significant
signal, which had a period of about 230 days, but with rather poor
sampling. To elucidate its presence and nature we undertook an
intensive monitoring campaign with the CARMENES spectrometer,
collecting precise radial-velocity measurements on every possible
night during 2016 and 2017. We also obtained overlapping observations
with the European Southern Observatory (ESO) HARPS and the HARPS-N
instruments. The combined Doppler monitoring of Barnard's star,
including archival and newly acquired observations, resulted in 771
radial-velocity epochs (nightly averages), with typical individual
precisions of 0.9-1.8m/s, obtained over a timespan of more than
20 years from seven different facilities, and yielded eight
independent datasets.
Objects:
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RA (2000) DE Designation(s)
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17 57 48.50 +04 41 36.1 Barnard's star = V* V2500 Oph
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
gl699rv.dat 45 771 Time-series measurements of radial velocity
gl699ha.dat 45 618 Time-series measurements of the Hα index
gl699s.dat 45 384 Time-series measurement of the S index of the
CaII H&K chromospheric lines
gl699ph.dat 52 1634 Time-series photometric measurements
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See also:
J/ApJ/764/131 : Long-term monitoring of Barnard's star velocity (Choi+, 2013)
Byte-by-byte Description of file: gl699rv.dat
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Bytes Format Units Label Explanations
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1- 9 A9 --- Inst Instrument (1)
11- 23 F13.5 d BJD Barycentric Julian Date of the mid-time
of the observation
29- 34 F6.3 m/s RV Radial velocity
41- 45 F5.3 m/s e_RV 1-sigma uncertainty in the radial velocity
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Note (1): Instruments used: APF, CARMENES, HARPSN, HARPSpost, HARPSpre, HIRES,
PFS and UVES.
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Byte-by-byte Description of file: gl699ha.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 A9 --- Inst Instrument (1)
11- 23 F13.5 d BJD Barycentric Julian Date of the mid-time
of the observation
28- 34 F7.5 --- Halpha Hα index
39- 45 F7.5 --- e_Halpha 1-sigma uncertainty in the Hα index
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Note (1): instruments used: APF, CARMENES, HARPSN, HARPSpost, HARPSpre, HIRES,
PFS and UVES.
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Byte-by-byte Description of file: gl699s.dat
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Bytes Format Units Label Explanations
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1- 9 A9 --- Inst Instrument (1)
11- 23 F13.5 d BJD Barycentric Julian Date of the mid-time
of the observation
28- 34 F7.5 --- Sindex S index
39- 45 F7.5 --- e_Sindex 1-sigma uncertainty in the S index
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Note (1): Instrument used: APF, HARPSN, HARPSpost, HARPSpre and HIRES.
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Byte-by-byte Description of file: gl699ph.dat
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Bytes Format Units Label Explanations
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1- 6 A6 --- Inst Instrument (1)
8- 16 A9 --- Filt Filter
18- 30 F13.5 d BJD Barycentric Julian Date of the mid-time
of the observation
35- 41 F7.4 mag dmag Differential magnitude
47- 52 F6.4 mag e_dmag 1-sigma uncertainty in the
differential magnitudes
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Note (1): Instruments used: AAVSO, APT, ASAS, MEarth, OAdM, RCT and SNO.
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 12-Feb-2019