TOI-1846 b: TESS Discovers a New Super-Earth Orbiting a Nearby M Dwarf Star

NASA’s Transiting Exoplanet Survey Satellite (TESS) has made another remarkable discovery: a new super-Earth exoplanet named TOI-1846 b. This alien world orbits a nearby M dwarf star and stands out due to its size and mass, being about twice as large and four times as massive as Earth

Key Facts About TOI-1846 b

Feature	Value
Planet Name	TOI-1846 b
Host Star	TOI-1846 (M dwarf)
Distance from Earth	~154 light-years (47 parsecs)
Planet Radius	1.79 ± 0.07 Earth radii
Planet Mass	4.4 (+1.6/−1.0) Earth masses
Orbital Period	3.93 days
Orbital Distance	0.036 AU (~5.4 million km)
Equilibrium Temperature	589 ± 20 K (approx. 295°C)
Density	4.2 g/cm³
Host Star Radius	0.41 solar radii
Host Star Mass	0.40 solar masses
Host Star Temperature	3568 ± 44 K
Host Star Age	~7.2 billion years

Discovery and Validation

• TESS detected periodic dips in brightness from the star TOI-1846, indicating a possible transiting planet.
• Follow-up ground-based photometric and spectroscopic observations confirmed the planetary nature of the signal1.
• High-resolution imaging ruled out background stars or stellar companions as the source of the transit signal.

What Makes TOI-1846 b Special?

• Super-Earth in the Radius Valley: TOI-1846 b’s size places it in the “radius valley,” a range where planets are rare due to atmospheric loss from stellar radiation. Its density suggests a rocky, potentially water-rich composition.
• Short Orbit: The planet completes an orbit around its star every 3.93 days, much closer than Mercury is to our Sun.
• M Dwarf Host: The host star is a cool, dim red dwarf, making it easier to detect planets in close orbits due to the star’s low luminosity.

Scientific Implications

• Water-Rich World: Based on its density and position in the radius valley, TOI-1846 b is likely a water-rich super-Earth, possibly with a secondary atmosphere.
• Exoplanet Demographics: Its discovery helps astronomers understand the distribution of rocky versus gaseous planets in close orbits, and the effects of stellar radiation on planetary atmospheres.

The Role of TESS

• TESS has revolutionized exoplanet discovery by monitoring the brightness of over 200,000 stars.
• With more than 7,600 exoplanet candidates and over 600 confirmed, TESS continues to expand our knowledge of planetary systems beyond our own.

The discovery of TOI-1846 b adds a fascinating new member to the growing family of super-Earths. Its proximity, size, and composition make it a valuable target for future studies on planetary formation, atmospheric evolution, and the potential for habitability in M dwarf systems.