New exoplanet discovered using ESPRESSO spectrometer

ESPRESSO radial velocities from L 363-38 after subtracting the linear displacement and adding the instrumental jitter to the error bars. Credit: Sartori et al., 2022

Using Echelle’s Rocky Exoplanet Spectrograph and Stable Spectroscopic Observations (ESPRESSO), astronomers from Switzerland and Austria have discovered an alien new world. The newly discovered exoplanet orbits a nearby M dwarf star, which is at least four times the mass of Earth. The result was reported in a paper published October 23 on arXiv.org.

ESPRESSO is the latest ultra-high-resolution spectrometer installed at the Very Large Telescope (VLT) in Chile, covering the spectral range from about 380 nm to 788 nm. The device is able to reach an accuracy that allows it to detect Earth-like planets around sun-like stars.

A team of astronomers led by Lia F. Sartori of the Swiss Federal Institute of Technology in Zurich, Switzerland, is performing a blind search of the radial velocity of espresso for planets around nearby stars. One of their targets was L 363-38 – an M dwarf located about 33.3 light-years away. They observed this star between December 12, 2020 and February 8, 2022, and obtained a total of 31 observations, which led to the discovery of a new planet.

“In the following, we report the discovery and characterization of a planet orbiting the nearby dwarf star ML 363-38. This is one of the few independent discoveries of planets using ESPRESSO to date,” the researchers wrote in the paper.

The newly discovered planet, named L 363-38 b, has a minimum mass of about 4.67 Earth masses and an estimated radius between 1.55 and 2.75 Earth radii. An exoplanet orbits its host every 8.78 days, at a distance of about 0.048 AU from it, and thus within the inner edge of the habitable zone. The equilibrium temperature L 363-38 b was calculated to be about 330 K.

The parent star L 363-38 (other designations: LHS 1134 and GJ 3049), an estimated age of 8 billion years, has a radius of about 0.274 solar radii and a mass of about 0.21 solar masses. The effective temperature of this star has been measured to be 3129 K.

Astronomers hypothesize that L 363-38 may be orbited by some other still undiscovered planet. They explain that, based on statistics from NASA’s Kepler and TESS missions, planets around M dwarfs are expected to occur in multiplanet systems. Hence, further observations of this planetary system using telescopes such as the James Webb Space Telescope (JWST), are required to detect the presence of other extrasolar worlds around L 363-38.

In closing notes, the study authors demonstrate the potential of ESPRESSO in discovering and investigating exoplanets around nearby M dwarf stars.

“In fact, the weak M stars make them challenging targets for the RV [radial velocity] Studies using tools like HARPS [High Accuracy Radial velocity Planet Searcher] behind a telescope with a diameter of 3.6 meters, but a spectrometer behind a telescope with a diameter of 8 meters such as ESPRESSO can collect enough light to accurately measure the RV in an efficient manner.”

more information:
Lia F. Sartori et al, L 363-38 b: a newly discovered planet with ESPRESSO orbiting a nearby dwarf star, arXiv (2022). doi: 10.48550/arxiv.2210.12710

Journal information:
arXiv

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