57 research outputs found
HD 2685 b: A hot Jupiter orbiting an early F-type star detected by TESS
We report on the confirmation of a transiting giant planet around the relatively hot (Teff = 6801 ± 76 K) star HD 2685, whose transit signal was detected in Sector 1 data of NASA’s TESS mission. We confirmed the planetary nature of the transit signal using Doppler velocimetric measurements with CHIRON, CORALIE, and FEROS, as well as using photometric data obtained with the Chilean-Hungarian Automated Telescope and the Las Cumbres Observatory. From the joint analysis of photometry and radial velocities, we derived the following parameters for HD 2685 b: P = 4.12688−0.00004+0.00005 days, e = 0.091−0.047+0.039, MP = 1.17 ± 0.12 MJ, and RP =1.44 ± 0.05 RJ. This system is a typical example of an inflated transiting hot Jupiter in a low-eccentricity orbit. Based on the apparent visual magnitude (V = 9.6 mag) of the host star, this is one of the brightest known stars hosting a transiting hot Jupiter, and it is a good example of the upcoming systems that will be detected by TESS during the two-year primary mission. This is also an excellent target for future ground- and space-based atmospheric characterization as well as a good candidate for measuring the projected spin-orbit misalignment angle through the Rossiter–McLaughlin effect
Evidence of extra-mixing in field giants as traced by lithium and carbon isotope ratio
Although not predicted by standard stellar evolution, it is known that the
surface abundance of light elements changes during the red giant branch (RGB)
as a result of extra-mixing. This is associated usually with thermohaline
mixing acting after the RGB bump. Peculiar lithium-enriched RGB stars might
also be related to either enhanced extra-mixing or pollution from external
sources. We measure the lithium (Li) abundance and carbon isotopic ratio
C12/C13 in a sample of 166 field red giants with -0.3<[Fe/H]<0.2, targeted by
the EXPRESS radial velocity program to analyze the effects of extra-mixing. The
Li abundance pattern is complicated to interpret, but the comparison between
RGB and core-He burning giants shows the effects of extra-mixing consistent
with thermohaline. The most Li-enriched giant in the sample was classified as a
RGB star close to the luminosity function bump with low C12/C13. Given that the
C12/C13 should not be affected by external mechanisms, contamination by an
external source, such as a planet, does not seem to be the source of the high
Li. The C12C13 presents new clues to describe the extra-mixing. There is a
decreasing correlation between mass and C12/C13 in the RGB and an increasing
correlation in the horizontal branch, which, once again, is consistent with
thermohaline mixing. Our data also shows a correlation between C12/C13 and
[Fe/H]. There is no evident impact of binarity either on Li or C12/C13. Our
sample shows behavior that is consistent with additional mixing acting after
the RGB bump. Li, which is heavily affected by rotational mixing and other
processes, does not show a clear trend. Instead, the C12/C13 could be the best
tool to study mixing in red giants. Additional measurements of C12/C13 in field
stars would greatly improve our ability to compare with models and understand
the mixing mechanisms.Comment: 15 pages, 12 figures, submitted to A&A, comments welcom
HD 2685 b: a hot Jupiter orbiting an early F-type star detected by TESS
We report on the confirmation of a transiting giant planet around the relatively hot (T_(eff) = 6801 ± 76 K) star HD 2685, whose transit signal was detected in Sector 1 data of NASA’s TESS mission. We confirmed the planetary nature of the transit signal using Doppler velocimetric measurements with CHIRON, CORALIE, and FEROS, as well as using photometric data obtained with the Chilean-Hungarian Automated Telescope and the Las Cumbres Observatory. From the joint analysis of photometry and radial velocities, we derived the following parameters for HD 2685 b: P = 4.12688_(−0.00004)^(+0.00005) days, e= 0.091_(−0.047)^(+0.039), M_P = 1.17 ± 0.12 M_J, and RP =1.44 ± 0.05 RJ. This system is a typical example of an inflated transiting hot Jupiter in a low-eccentricity orbit. Based on the apparent visual magnitude (V = 9.6 mag) of the host star, this is one of the brightest known stars hosting a transiting hot Jupiter, and it is a good example of the upcoming systems that will be detected by TESS during the two-year primary mission. This is also an excellent target for future ground- and space-based atmospheric characterization as well as a good candidate for measuring the projected spin-orbit misalignment angle through the Rossiter–McLaughlin effect
EPIC247098361b: a transiting warm Saturn on an eccentric days orbit around a star
We report the discovery of EPIC247098361b using photometric data of the
Kepler K2 satellite coupled with ground-based spectroscopic observations.
EPIC247098361b has a mass of M M, a radius of
R R, and a moderately low equilibrium temperature of
K due to its relatively large star-planet separation of
AU. EPIC247098361b orbits its bright () late F-type host star
in an eccentric orbit () every 11.2 days, and is one of only
four well characterized warm Jupiters having hosts stars brighter than .
We estimate a heavy element content of 20 7 M for
EPIC247098361b, which is consistent with standard models of giant planet
formation. The bright host star of EPIC247098361b makes this system a well
suited target for detailed follow-up observations that will aid in the study of
the atmospheres and orbital evolution of giant planets at moderate separations
from their host stars.Comment: 11 pages, 10 figures, submitted to MNRA
A dense mini-Neptune orbiting the bright young star HD 18599
© 2022 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society. This is the accepted manuscript version of an article which has been published in final form at https://doi.org/10.1093/mnras/stac2845Very little is known about the young planet population because the detection of small planets orbiting young stars is obscured by the effects of stellar activity and fast rotation which mask planets within radial velocity and transit data sets. The few planets that have been discovered in young clusters generally orbit stars too faint for any detailed follow-up analysis. Here we present the characterization of a new mini-Neptune planet orbiting the bright (V=9) and nearby K2 dwarf star, HD 18599. The planet candidate was originally detected in TESS light curves from Sectors 2, 3, 29, and 30, with an orbital period of 4.138~days. We then used HARPS and FEROS radial velocities, to find the companion mass to be 25.54.6~M. When we combine this with the measured radius from TESS, of 2.700.05~R, we find a high planetary density of 7.11.4~g cm. The planet exists on the edge of the Neptune Desert and is the first young planet (300 Myr) of its type to inhabit this region. Structure models argue for a bulk composition to consist of 23% HO and 77% Rock and Iron. Future follow-up with large ground- and space-based telescopes can enable us to begin to understand in detail the characteristics of young Neptunes in the galaxy.Peer reviewe
Three long period transiting giant planets from TESS
We report the discovery and orbital characterization of three new transiting
warm giant planets. These systems were initially identified as presenting
single transit events in the light curves generated from the full frame images
of the Transiting Exoplanet Survey Satellite (TESS). Follow-up radial velocity
measurements and additional light curves were used to determine the orbital
periods and confirm the planetary nature of the candidates. The planets orbit
slightly metal-rich late F- and early G-type stars. We find that TOI 4406b has
a mass of = 0.30 0.04 , a radius of = 1.00 0.02
, and a low eccentricity orbit (e=0.15 0.05) with a period of P=
30.08364 0.00005 d . TOI 2338b has a mass of = 5.98 0.20
, a radius of = 1.00 0.01 , and a highly eccentric orbit (e=
0.676 0.002 ) with a period of P= 22.65398 0.00002 d . Finally, TOI
2589b has a mass of = 3.50 0.10 , a radius of = 1.08
0.03 , and an eccentric orbit (e = 0.522 0.006 ) with a
period of P= 61.6277 0.0002 d . TOI 4406b and TOI 2338b are enriched in
metals compared to their host stars, while the structure of TOI 2589b is
consistent with having similar metal enrichment to its host star.Comment: 24 pages, 16 figures, accepted in A
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