by The hunt for habitable extrasolar planets continues! Thanks to dedicated missions like Kepler, TESS and Hubble, the number of confirmed extrasolar planets has exploded in the last fifteen years (with 5,272 confirmed and counting!).
At the same time, next-generation telescopes, spectrometers and advanced imaging techniques are now enabling astronomers to study exoplanet atmospheres more closely. In short, the field is shifting from the discovery process to characterization, allowing astronomers to more tightly constrain habitability.
Finding potentially habitable “Earth-like” planets around these fainter stars is the purpose of the high-resolution Calar Alto search for M dwarfs using Exoearths with Near-Infrared and Optical Echelle Spectrographs (CARMENES), located at the Calar Alto Observatory located in Spain.
Challenging planet hunt
In a study published in Astronomy & Astrophysics today the CARMENES consortium published data (Data Release 1) from about 20,000 observations made between 2016 and 2020. Among measurements obtained from 362 nearby cool stars, DR1 contained data from 59 new planets.
The CARMENES instrument is an optical and near-infrared spectrograph mounted on the 3.5 meter telescope and is one of the most sophisticated planetary hunts in the world using the radial velocity method.
Also known as Doppler spectroscopy, this method involves measuring light from distant stars with spectrometers to look for signs of redshift and blueshift — which show if the planet is moving back and forth. This motion indicates the presence of gravitational forces acting on the star (i.e., a system of orbiting planets) and can provide accurate mass estimates.
The CARMENES consortium that designed and built this instrument includes more than 200 scientists and engineers from 11 Spanish and German institutions.
Since 2015, the goal of the consortium has been to search for terrestrial exoplanets near nearby red dwarf stars. Since then, the CARMENES instrument has doubled the number of known exoplanets around nearby M-type stars using the radial velocity method.
The 59 exoplanets they identified between 2016 and 2019 are either new discoveries or confirmations of previously discovered candidates, including 6 Jupiter-like gas giants, 10 Neptune-like gas giants, and 43 Earths and super-Earths. A dozen of these latter planets have been found to orbit within the stars’ circumsolar habitable zones.
“Since its commissioning, CARMENES has reanalyzed 17 known planets and detected and confirmed 59 new planets around stars near our solar system, making a significant contribution to expanding the count of nearby exoplanets,” said Ignasi Ribas. a researcher at ICE-CSIC and Director of the Institute of Space Studies of Catalonia (IEEC), who led the study, in a recent MPIA press release.
“To determine the existence of planets around a star, we observe it at least 50 times,” added Juan Carlos Morales, an IEEC researcher at ICE-CSIC. “Although the first round of data has already been released to provide access to the scientific community, the observations are still ongoing.”
Artist’s rendering of a rocky Earth-mass exoplanet like Wolf 1069 b orbiting a red dwarf star.
Credit: NASA/Ames Research Center/Daniel Rutter
Stimulating dates
The paper published in Astronomy & Astrophysics is the 100th study by the CARMENES consortium demonstrating the project’s success in detecting exoplanets around fainter, low-mass stars. Between 2016 and 2019, CARMENES observed almost half of all nearby M-type stars in two near-infrared wavelength ranges – 0.52 to 0.96 µm and 0.96 to 1.71 µm – some of them only from the southern hemisphere can be observed.
In addition, the spectra obtained provided information about the atmospheres of the stars and their planets, which is essential for characterization.
The consortium team hopes that the release of this first large dataset will stimulate further research and discovery. Experts are also using the visible light data from the studied stars to improve CARMENE’s infrared data processing.
Once this information is released, astronomers will have another large data set of observations to work with. In the meantime, the consortium is conducting further observations of the same stars through CARMENES Legacy-Plus, which began in 2021 and is expected to last until the end of 2023.
The CARMENES consortium plans to survey about 300 late-type M5V main sequence stars – red dwarf suns about 0.162 times the mass of the Sun. The ultimate goal is to discover up to 2 million Earth-like planets orbiting within the habitable zones of M-type stars. This will go a long way toward settling the debate on whether or not life can survive under “red skies,” which remains the subject of considerable debate.
This article was originally published on universe today by Matt Williams. Read the original article here.
