Descoberta uma "superterra" na zona habitável de uma estrela anã vermelha.

 

Uma pesquisa recente, publicada na revista Monthly Notices of the Royal Astronomical Society, relata a descoberta de uma superterra orbitando uma estrela anã vermelha há "apenas" 137 anos-luz de distância da Terra. Chamado de TOI-715b, o planeta tem cerca de 1,55 do raio do nosso e está dentro da zona habitável da estrela. 

Dentro do mesmo sistema, foi ainda observado um segundo planeta do mesmo tamanho que a Terra que, se confirmado, será a menor em zona habitável que o Satélite de Pesquisa de Exoplanetas em Trânsito da NASA (TESS) encontrou até agora. 

Artigo completo aqui.

A 1.55 R⊕ habitable-zone planet hosted by TOI-715, an M4 star near the ecliptic South Pole.

ABSTRACT 

A new generation of observatories is enabling detailed study of exoplanetary atmospheres and the diversity of alien climates, allowing us to seek evidence for extraterrestrial biological and geological processes. Now is therefore the time to identify the most unique planets to be characterized with these instruments. In this context, we report on the discovery and validation of TOI-715 b, a planet orbiting its nearby (42 pc) M4 host (TOI-715/TIC 271971130) with a period 19,288 d. TOI-715 b was first identified by TESS and validated using ground-based photometry, high-resolution imaging and statistical validation. The planet’s orbital period combined with the stellar effective temperature give this planet an installation⁠, placing it within the most conservative definitions of the habitable zone for rocky planets. TOI-715 b’s radius falls exactly between two measured locations of the M-dwarf radius valley; characterizing its mass and composition will help understand the true nature of the radius valley for low-mass stars. We demonstrate TOI-715 b is amenable for characterization using precise radial velocities and transmission spectroscopy. Additionally, we reveal a second candidate planet in the system, TIC 271971130.02, with a potential orbital period of 25,6 d and a radius of 1,066⁠, just inside the outer boundary of the habitable zone, and near a 4:3 orbital period commensurability. Should this second planet be confirmed, it would represent the smallest habitable zone planet discovered by TESS to date. 

 Keywords: planets and satellites: detection, planets and satellites: fundamental parameters, planets and satellites: terrestrial planets