The project CARMEN IS has just published data corresponding to about 20,000 observations made between 2016 and 2020 of a sample of 362 nearby cool stars. The research participated Calar Alto Observatory (Almeria), where Earth-like exoplanets (rocky and temperate) were sought. These stars can harbor water on their surface if they are located in their star’s so-called habitable zone. The team discovered 59 of these celestial bodies, including a dozen potentially habitable ones. The study was published in the journal Astronomy & Astrophysics.
The high-resolution spectra obtained are used to determine the star’s velocity with an accuracy of one meter per second, which makes it possible to find small planets around low-mass stars.
CARMENES is the name of the scientific project, but also of the instrument with which the observations are made and of the consortium that was in charge of its design and construction. More than 200 scientists and engineers from 11 Spanish and German institutions bring the project to life, in which researchers from Institute of Space Studies of Catalonia (IEEC) in Institute of Space Sciences (ICE-CSIC) have a prominent role.
terrestrial exoplanets
This instrument is an optical and near-infrared spectrograph, that is, a device that measures both visible and infrared light from the objects at which it points. It was installed in 2015 at the Calar Alto Observatory with the aim of finding terrestrial-type exoplanets in nearby cool stars (the so-called red dwarfs). The light collected from a given star (the stellar spectrum) can reveal the presence of exoplanets, since it allows measuring the small movements of the star produced by the gravitational attraction of the planets that orbit it.
The high-resolution spectra obtained with this instrument are used to determine the star’s velocity with an accuracy of one meter per second, which represents a first-rate technological challenge. This makes it possible to find small planets around low-mass stars, say the authors.
Planets discovered with the same CARMENES method, but with other instruments
“Since it entered into operation, CARMENES has reanalyzed 17 known planets and has discovered and confirmed 59 new planets in the vicinity of our solar system, notably contributing to expanding the census of nearby exoplanets”, explains Ignasi Ribas, director of the IEEC and first author from work.
The CARMENES spectrograph has multiplied the number of exoplanets we know around nearby cool stars
First batch of data
This instrument has multiplied the number of exoplanets we know around nearby cool stars, doubling those detected with the previously exposed method. About half of all nearby small stars were observed with the spectrograph (a portion of them can only be seen from the southern hemisphere). In addition, the spectra obtained also provide very valuable information about the atmospheres of stars and their planets, among other characteristics.
The investigation released the data corresponding to the information obtained with visible light. Experts are still getting better at processing the infrared data, so when it’s published, astronomers will have a second large set of observations to work with.
The project continues on CARMENES Legacy-Plus, which started in 2021 and continues to make more observations of the same stars. “To determine the existence of planets around a star, we observe it at least 50 times”, explains Juan Carlos Morales, researcher at the IEEC. “Although the first round of data has now been published for the scientific community to access, these series of observations are not yet complete,” he adds. Observations made in this extension of the project will continue at least until the end of 2023.
Reference:
I. Ribas, A. Reiners et al. “CARMENES searches for exoplanets around M dwarfs. Time Guaranteed Observation Data Release 1 (2016-2020)”. Astronomy & Astrophysics (February 22, 2023).