Eureka moment as two teams of astronomers find new nearest potentially habitable Earth-size planet near our solar system

Good news! We are not alone!

"... analysed observation data from NASA’s TESS (Transiting Exoplanet Survey Satellite) and says it reveals “…the nearest transiting, temperate, Earth-sized planet found to date.”

The exoplanet is named Gliese 12 b. It orbits the small but bright and low magnetic activity star Gliese 12.

Their finding is documented in a paper ..., and a Japanese team has simultaneously released research ... into the same planet saying: “The discovery of a planet similar to Venus around a star in the neighborhood of the Solar System raises hopes that astronomers may someday unlock the secret to why life appeared on Earth.” ..."

From abstract1:

"We report on the discovery of Gliese 12 b, the nearest transiting temperate, Earth-sized planet found to date. Gliese 12 is a bright (V = 12.6 mag, K = 7.8 mag) metal-poor M4V star only 12.162 ± 0.005 pc away from the Solar system with one of the lowest stellar activity levels known for M-dwarfs. A planet candidate was detected by TESS based on only 3 transits in sectors 42, 43, and 57, with an ambiguity in the orbital period due to observational gaps. We performed follow-up transit observations with CHEOPS and ground-based photometry with MINERVA-Australis, SPECULOOS, and Purple Mountain Observatory, as well as further TESS observations in sector 70. We statistically validate Gliese 12 b as a planet with an orbital period of 12.76144 ± 0.00006 d and a radius of 1.0 ± 0.1 R⊕, resulting in an equilibrium temperature of ∼315 K. Gliese 12 b has excellent future prospects for precise mass measurement, which may inform how planetary internal structure is affected by the stellar compositional environment. Gliese 12 b also represents one of the best targets to study whether Earth-like planets orbiting cool stars can retain their atmospheres, a crucial step to advance our understanding of habitability on Earth and across the galaxy."

From abstract2:

"Recent discoveries of Earth-sized planets transiting nearby M dwarfs have made it possible to characterize the atmospheres of terrestrial planets via follow-up spectroscopic observations. However, the number of such planets receiving low insolation is still small, limiting our ability to understand the diversity of the atmospheric composition and climates of temperate terrestrial planets. We report the discovery of an Earth-sized planet transiting the nearby (12 pc) inactive M3.0 dwarf Gliese 12 (TOI-6251) with an orbital period (Porb) of 12.76 days. The planet, Gliese 12 b, was initially identified as a candidate with an ambiguous Porb from TESS data. We confirmed the transit signal and Porb using ground-based photometry with MuSCAT2 and MuSCAT3, and validated the planetary nature of the signal using high-resolution images from Gemini/NIRI and Keck/NIRC2 as well as radial velocity (RV) measurements from the InfraRed Doppler instrument on the Subaru 8.2 m telescope and from CARMENES on the CAHA 3.5 m telescope. X-ray observations with XMM-Newton showed the host star is inactive, with an X-ray-to-bolometric luminosity ratio of [picture]. Joint analysis of the light curves and RV measurements revealed that Gliese 12 b has a radius of 0.96 ± 0.05 R⊕, a 3σ mass upper limit of 3.9 M⊕, and an equilibrium temperature of 315 ± 6 K assuming zero albedo. The transmission spectroscopy metric (TSM) value of Gliese 12 b is close to the TSM values of the TRAPPIST-1 planets, adding Gliese 12 b to the small list of potentially terrestrial, temperate planets amenable to atmospheric characterization with JWST."

Eureka moment as astronomers find new "potentially habitable" Earth-size planet

Gliese 12 b, a temperate Earth-sized planet at 12 parsecs discovered with TESS and CHEOPS (open access)

Gliese 12 b: A Temperate Earth-sized Planet at 12 pc Ideal for Atmospheric Transmission Spectroscopy (open access)

Figure 4 (from first research article) Historical images of the field surrounding Gliese 12. Left: 2MASS J band image from 1998 (Skrutskie et al. 2006) Right: DSS image from 1949 (Lasker et al. 1990). The blue circle indicate the location of Gliese 12 when it was observed by TESS. The blue cross indicates the location of Gliese 12 when it was observed by 2MASS. Blue dots indicate all the other stars in the field-of-view within Δ T Mag 7.5 of Gliese 12. A background eclipsing binary that can mimic the 1.1 ppt transit signal needs to be within Δ T Mag 7.5 of Gliese 12. These images can be used to rule out the existence of such stars when TESS is observing Gliese 12.