New planet detected around Proxima Centauri, closest star our solar
system

Date:
February 10, 2022
Source:
ESO
Summary:
Astronomers have found evidence of another planet orbiting Proxima
Centauri, the closest star to our Solar System. This candidate
planet is the third detected in the system and the lightest yet
discovered orbiting this star. At just a quarter of Earth's mass,
the planet is also one of the lightest exoplanets ever found.



FULL STORY ========================================================================== [Illustration of | Credit: (c) dottedyeti / stock.adobe.com] Illustration
of exoplanet orbiting star (stock image).

Credit: (c) dottedyeti / stock.adobe.com [Illustration of | Credit: (c) dottedyeti / stock.adobe.com] Illustration of exoplanet orbiting star
(stock image).

Credit: (c) dottedyeti / stock.adobe.com Close A team of astronomers using
the European Southern Observatory's Very Large Telescope (ESO's VLT) in
Chile have found evidence of another planet orbiting Proxima Centauri,
the closest star to our Solar System. This candidate planet is the third detected in the system and the lightest yet discovered orbiting this
star. At just a quarter of Earth's mass, the planet is also one of the
lightest exoplanets ever found.


==========================================================================
"The discovery shows that our closest stellar neighbour seems to be
packed with interesting new worlds, within reach of further study and
future exploration," explains Joa~o Faria, a researcher at the Instituto
de Astrofi'sica e Cie^ncias do Espac,o, Portugal and lead author of the
study published today in Astronomy & Astrophysics. Proxima Centauri is
the closest star to the Sun, lying just over four light-years away.

The newly discovered planet, named Proxima d, orbits Proxima Centauri
at a distance of about four million kilometres, less than a tenth of
Mercury's distance from the Sun. It orbits between the star and the
habitable zone -- the area around a star where liquid water can exist
at the surface of a planet - - and takes just five days to complete one
orbit around Proxima Centauri.

The star is already known to host two other planets: Proxima b, a planet
with a mass comparable to that of Earth that orbits the star every 11
days and is within the habitable zone, and candidate Proxima c, which
is on a longer five- year orbit around the star.

Proxima b was discovered a few years ago using the HARPS instrument
on ESO's 3.6-metre telescope. The discovery was confirmed in 2020 when scientists observed the Proxima system with a new instrument on ESO's VLT
that had greater precision, the Echelle SPectrograph for Rocky Exoplanets
and Stable Spectroscopic Observations (ESPRESSO). It was during these
more recent VLT observations that astronomers spotted the first hints
of a signal corresponding to an object with a five-day orbit. As the
signal was so weak, the team had to conduct follow-up observations with ESPRESSO to confirm that it was due to a planet, and not simply a result
of changes in the star itself.

"After obtaining new observations, we were able to confirm this signal
as a new planet candidate," Faria says. "I was excited by the challenge
of detecting such a small signal and, by doing so, discovering an
exoplanet so close to Earth." At just a quarter of the mass of Earth,
Proxima d is the lightest exoplanet ever measured using the radial
velocity technique, surpassing a planet recently discovered in the L
98-59 planetary system. The technique works by picking up tiny wobbles
in the motion of a star created by an orbiting planet's gravitational
pull. The effect of Proxima d's gravity is so small that it only causes
Proxima Centauri to move back and forth at around 40 centimetres per
second (1.44 kilometres per hour).

"This achievement is extremely important," says Pedro Figueira, ESPRESSO instrument scientist at ESO in Chile. "It shows that the radial velocity technique has the potential to unveil a population of light planets,
like our own, that are expected to be the most abundant in our galaxy
and that can potentially host life as we know it." "This result clearly
shows what ESPRESSO is capable of and makes me wonder about what it will
be able to find in the future," Faria adds.

ESPRESSO's search for other worlds will be complemented by ESO's
Extremely Large Telescope (ELT), currently under construction in the
Atacama Desert, which will be crucial to discovering and studying many
more planets around nearby stars.

========================================================================== Story Source: Materials provided by ESO. Note: Content may be edited
for style and length.


========================================================================== Related Multimedia:
* YouTube_video:_Ultralight_Planet_Found_Next_Door_(ESOcast_250_Light) ========================================================================== Journal Reference:
1. J. P. Faria, A. Sua'rez Mascaren~o, P. Figueira, A. M. Silva,
M. Damasso,
O. Demangeon, F. Pepe, N. C. Santos, R. Rebolo, S. Cristiani, V.

Adibekyan, Y. Alibert, R. Allart, S. C. C. Barros, A. Cabral, V.

D'Odorico, P. Di Marcantonio, X. Dumusque, D. Ehrenreich,
J. I. Gonza'lez Herna'ndez, N. Hara, J. Lillo-Box, G. Lo Curto,
C. Lovis, C. J. A. P.

Martins, D. Me'gevand, A. Mehner, G. Micela, P. Molaro, N. J. Nunes,
E.

Palle', E. Poretti, S. G. Sousa, A. Sozzetti, H. Tabernero,
S. Udry, M.

R. Zapatero Osorio. A candidate short-period sub-Earth orbiting
Proxima Centauri. Astronomy & Astrophysics, 2022; 658: A115 DOI:
10.1051/0004- 6361/202142337 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/02/220210085019.htm

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