The CARMENES search for exoplanets around M dwarfs. Two temperate Earth-mass planet candidates around Teegarden’s Star. (arXiv:1906.07196v1 [astro-ph.EP])
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Context. Teegarden’s Star is the brightest and one of the nearest ultra-cool
dwarfs in the solar neighbourhood. For its late spectral type (M7.0V), the star
shows relatively little activity and is a prime target for near-infrared radial
velocity surveys such as CARMENES.

Aims. As part of the CARMENES search for exoplanets around M dwarfs, we
obtained more than 200 radial-velocity measurements of Teegarden’s Star and
analysed them for planetary signals.

Methods. We find periodic variability in the radial velocities of Teegarden’s
Star. We also studied photometric measurements to rule out stellar brightness
variations mimicking planetary signals.

Results. We find evidence for two planet candidates, each with $1.1M_oplus$
minimum mass, orbiting at periods of 4.91 and 11.4 d, respectively. No evidence
for planetary transits could be found in archival and follow-up photometry.
Small photometric variability is suggestive of slow rotation and old age.

Conclusions. The two planets are among the lowest-mass planets discovered so
far, and they are the first Earth-mass planets around an ultra-cool dwarf for
which the masses have been determined using radial velocities.

Context. Teegarden’s Star is the brightest and one of the nearest ultra-cool
dwarfs in the solar neighbourhood. For its late spectral type (M7.0V), the star
shows relatively little activity and is a prime target for near-infrared radial
velocity surveys such as CARMENES.

Aims. As part of the CARMENES search for exoplanets around M dwarfs, we
obtained more than 200 radial-velocity measurements of Teegarden’s Star and
analysed them for planetary signals.

Methods. We find periodic variability in the radial velocities of Teegarden’s
Star. We also studied photometric measurements to rule out stellar brightness
variations mimicking planetary signals.

Results. We find evidence for two planet candidates, each with $1.1M_oplus$
minimum mass, orbiting at periods of 4.91 and 11.4 d, respectively. No evidence
for planetary transits could be found in archival and follow-up photometry.
Small photometric variability is suggestive of slow rotation and old age.

Conclusions. The two planets are among the lowest-mass planets discovered so
far, and they are the first Earth-mass planets around an ultra-cool dwarf for
which the masses have been determined using radial velocities.

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