An article to be published in “The Astronomical Journal” reports the discovery of a super-Earth that was cataloged as LTT 1445Ab thanks to NASA’s TESS space telescope in a research coordinated by the Harvard-Smithsonian Center for Astrophysics. This exoplanet orbits a red dwarf and from the estimates seem too close to it to have the potential to host life forms similar to the Earth’s but it’s interesting because that star has two companions, red dwarfs as well, and orbits them.
Approximately 22.5 light-years from Earth, the exoplanet LTT 1445Ab was discovered using the TESS space telescope, launched April 18, 2018. Its star has mass and size that are about a quarter of the Sun’s but it’s so close to it that its year lasts just 5.36 days. The consequence is that LTT 1445Ab receives an amount of energy about 5 times what the Earth receives from the Sun and the temperature on its surface is estimated in peaks of 155° Celsius (311 degrees Fahrenheit). As if the proximity was not enough, the star is cataloged as a flare star and that means that it’s a variable star subject to sudden brightness changes, even if of short duration, with very intense flares that hit its planet.
The exoplanet LTT 1445Ab is rocky, with a diameter that is about 1.35 times the Earth’s. However, due to the conditions present on its surface water can’t be in its liquid state, a condition needed to host life forms similar to the Earth’s. The conditions must be hellish and if it ever had an atmosphere it could have become a super-Venus with a runaway greenhouse effect. There are various astronomers interested in searching for Venus-like planets to try to understand under what circumstances a planet can become so hot.
Follow-up observations will be necessary to understand if the exoplanet LTT 1445Ab has an atmosphere. The first ones have already started and the HARPS (High Accuracy Radial Velocity Planet Searcher) spectrograph mounted on the 3.6-meter telescope at ESO’s La Silla Observatory in Chile helped to have a first estimate of its mass even though it’s rough since there’s a maximum value of 8.4 times the Earth’s. If a value close to that would be confirmed it would mean that that exoplanet is really dense given that a density close to the Earth’s would give a mass about 2.5 times the Earth’s.
Another reason of interest in the exoplanet LTT 1445Ab is that it’s part of a triple system, called LTT 1445 or LTT 1445ABC, composed of three red dwarfs. Astronomers want to understand in what conditions a planet can have a stable orbit in a multiple system so this will certainly be the subject of more studies from this point of view as well.
The alignment of the stars in the LTT 1445ABC system and of the exoplanet LTT 1445Ab suggest that the whole system is co-planar, which means that they all lie on the same plane. If this were confirmed, it could mean that originally there was only one protostellar nucleus that fragmented very soon. This would be another reason to study it, also thinking about planetary formation mechanisms.
Because the exoplanet LTT 1445Ab is in the neighborhood from an astronomical point of view, it will be relatively easy to conduct more follow-up observations. It’s certainly not another planet that can be sold of as an Earth twin in clickbait titles but its discovery shows how certain exoplanets can be very interesting for many reasons other than their habitability potential.
