2 research outputs found
An unusually low density ultra-short period super-Earth and three mini-Neptunes around the old star TOI-561
Based on HARPS-N radial velocities (RVs) and TESS photometry, we present a
full characterisation of the planetary system orbiting the late G dwarf
TOI-561. After the identification of three transiting candidates by TESS, we
discovered two additional external planets from RV analysis. RVs cannot confirm
the outer TESS transiting candidate, which would also make the system
dynamically unstable. We demonstrate that the two transits initially associated
with this candidate are instead due to single transits of the two planets
discovered using RVs. The four planets orbiting TOI-561 include an ultra-short
period (USP) super-Earth (TOI-561 b) with period d, mass
M and radius
R, and three mini-Neptunes: TOI-561 c, with d,
M, R;
TOI-561 d, with d, M,
R; and TOI-561 e, with
d, M,
R. Having a density of g cm, TOI-561 b is the
lowest density USP planet known to date. Our N-body simulations confirm the
stability of the system and predict a strong, anti-correlated, long-term
transit time variation signal between planets d and e. The unusual density of
the inner super-Earth and the dynamical interactions between the outer planets
make TOI-561 an interesting follow-up target
TOI-4010: A System of Three Large Short-Period Planets With a Massive Long-Period Companion
We report the confirmation of three exoplanets transiting TOI-4010
(TIC-352682207), a metal-rich K dwarf observed by TESS in Sectors 24, 25, 52,
and 58. We confirm these planets with HARPS-N radial velocity observations and
measure their masses with 8 - 12% precision. TOI-4010 b is a sub-Neptune ( days, , ) in the hot Neptune desert, and is one of the
few such planets with known companions. Meanwhile, TOI-4010 c ( days,
, ) and TOI-4010 d ( days, , )
are similarly-sized sub-Saturns on short-period orbits. Radial velocity
observations also reveal a super-Jupiter-mass companion called TOI-4010 e in a
long-period, eccentric orbit ( days and based on
available observations). TOI-4010 is one of the few systems with multiple
short-period sub-Saturns to be discovered so far.Comment: 26 pages, 16 figures, published in A