&6^^^12 — JKURZWEIL
&6^^^12 — JKURZWEIL
In-Space Manufacturing and Assembly
Entry, Descent and Landing
Advanced Communications, Navigation and Avionics
The new worlds orbit a star named GJ 357, an M-type dwarf about one-third the Sun’s mass and size and about 40% cooler that our star. The system is located 31 light-years away in the constellation Hydra. In February, TESS cameras caught the star dimming slightly every 3.9 days, revealing the presence of a transiting exoplanet — a world beyond our solar system — that passes across the face of its star during every orbit and briefly dims the star’s light.
To date, GJ 357 b is the second nearest (d = 9.44 pc) transiting planet to the Sun after HD 219134 b (Motalebi et al. 2015, d = 6.53 pc), and the closest around an M dwarf. Besides, it is amenable to future detailed atmospheric characterization, opening the door to new studies for atmospheric characterization of Earth-like planet atmospheres (Pallé et al. 2009).
Radial velocities discovered two more planets in the system at 9.12 (GJ 357 c) and 55.6 days (GJ 357 d), with minimum masses of 3.59+/-0.50 and 6.1+/-1 Earth masses, and an irradiation of 4.4 and 0.38 Earths irradiation, respectively. GJ 357 d receives slightly less stellar irradiation than Mars does in our own Solar System, which puts it in the Habitable Zone for its host star. GJ 357 d could not have been detected with TESS and whether it transits remains an open question.
TOI 270, also known as TIC 259377017, 2MASS J04333970-5157222 and L 231-32, is approximately 73 light-years away from Earth.
“The TOI-270 system shows great potential for accurate characterization and formation studies of small planets near the habitable zone,” the astronomers said.
“It will be a prime target for future studies since: (i) its near-resonance allows the detection of transit timing variations for precise mass measurements and detailed dynamical studies; (ii) its brightness enables independent radial velocity mass measurements; (iii) the outer planets are ideal for atmospheric characterization via transmission spectroscopy with the future James Webb Space Telescope (JWST); and (iv) the quiet host star is well suited for future searches of terrestrial planets within the habitable zone.”