PR Image eso2516cLocation in the sky of the rogue planet Cha 1107-7626 (visible light)
Astronomers have identified an enormous
‘growth spurt’ in a so-called rogue planet. Unlike the planets in our
Solar System, these objects do not orbit stars, free-floating on their
own instead. The new observations, made with the European Southern
Observatory’s Very Large Telescope (ESO’s VLT), reveal that this
free-floating planet is eating up gas and dust from its surroundings at a
rate of six billion tonnes a second. This is the strongest growth rate
ever recorded for a rogue planet, or a planet of any kind, providing
valuable insights into how they form and grow.
“
People may think of planets as quiet and stable worlds, but with
this discovery we see that planetary-mass objects freely floating in
space can be exciting places,” says Víctor Almendros-Abad, an
astronomer at the Astronomical Observatory of Palermo, National
Institute for Astrophysics (INAF), Italy and lead author of the new
study.
The newly studied object, which has a mass five to 10 times the mass
of Jupiter, is located about 620 light-years away in the constellation
Chamaeleon. Officially named Cha 1107-7626, this rogue planet is still
forming and is fed by a surrounding disc of gas and dust. This material
constantly falls onto the free-floating planet, a process known as
accretion. However, the team led by Almendros-Abad has now found that
the rate at which the young planet is accreting is not steady.
By August 2025, the planet was accreting about eight times faster
than just a few months before, at a rate of six billion tonnes per
second! “
This is the strongest accretion episode ever recorded for a planetary-mass object,” says Almendros-Abad. The discovery, published today in
The Astrophysical Journal Letters, was made with the
X-shooter spectrograph on ESO’s
VLT, located in Chile’s Atacama Desert. The team also used data from the
James Webb Space Telescope, operated by the US, European and Canadian
space agencies, and archival data from the
SINFONI spectrograph on ESO's VLT.
"
The origin of rogue planets remains an open question: are they
the lowest-mass objects formed like stars, or giant planets ejected from
their birth systems?” asks co-author Aleks Scholz, an astronomer
at the University of St Andrews, United Kingdom. The findings indicate
that at least some rogue planets may share a similar formation path to
stars since similar bursts of accretion have been spotted in young stars
before. As co-author Belinda Damian, also an astronomer at the
University of St Andrews, explains: “
This discovery blurs the line
between stars and planets and gives us a sneak peek into the earliest
formation periods of rogue planets.”
By comparing the light emitted before and during the burst,
astronomers gathered clues about the nature of the accretion process.
Remarkably, magnetic activity appears to have played a role in driving
the dramatic infall of mass, something that has only been observed in
stars before. This suggests that even low-mass objects can possess
strong magnetic fields capable of powering such accretion events. The
team also found that the chemistry of the disc around the planet changed
during the accretion episode, with water vapour being detected during
it but not before. This phenomenon had been spotted in stars but never
in a planet of any kind.
Free-floating planets are difficult to detect, as they are very
faint, but ESO’s upcoming Extremely Large Telescope (ELT), operating
under the world's darkest skies for astronomy, could change that. Its
powerful instruments and giant main mirror will enable astronomers to
uncover and study more of these lonely planets, helping them to better
understand how star-like they are. As co-author and ESO astronomer
Amelia Bayo puts it: “
The idea that a planetary object can behave
like a star is awe-inspiring and invites us to wonder what worlds beyond
our own could be like during their nascent stages.”
More information
This research was presented in a paper titled “Discovery of an Accretion Burst in a Free-Floating
Planetary-Mass Object” to appear in The Astrophysical Journal Letters (doi:10.3847/2041-8213/ae09a8).
The team is composed of V. Almendros-Abad (Istituto Nazionale di
Astrofisica - Osservatorio Astronomico di Palermo, Italy), Aleks Scholz
(School of Physics & Astronomy, University of St Andrews, United
Kingdom [St Andrews]), Belinda Damian (St Andrews), Ray Jayawardhana
(Department of Physics & Astronomy, Johns Hopkins University, USA
[JHU]), Amelia Bayo (European Southern Observatory, Germany), Laura
Flagg (JHU), Koraljka Mužić (Instituto de Astrofísica e Ciências do
Espaço, Faculdade de Ciências, Universidade de Lisboa, Portugal),
Antonella Natta (School of Cosmic Physics, Dublin Institute for Advanced
Studies and University College Dublin, Ireland) Paola Pinilla (Mullard
Space Science Laboratory, University College London, UK) and Leonardo
Testi (Dipartimento di Fisica e Astronomia, Università di Bologna,
Italy).
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Links
Contacts
Víctor Almendros-Abad
INAF Astronomical Observatory of Palermo
Palermo, Italy
Tel: +39 3762144093
Email: victor.almendrosabad@inaf.it
Aleks Scholz
University of St. Andrews
St. Andrews, United Kingdom
Tel: +44 (0)1334 46 1668
Email: as110@st-andrews.ac.uk
Belinda Damian
University of St. Andrews
St. Andrews, United Kingdom
Tel: +44 (0)1334 46 3098
Email: bd64@st-andrews.ac.uk
Amelia Bayo
European Southern Observatory
Garching, Germany
Tel: +49 89 3200 6499
Email: AmeliaMaria.BayoAran@eso.org
Bárbara Ferreira
ESO Media Manager
Garching, Germany
Tel: +49 89 3200 6670
Cell: +49 151 241 664 00
Email: press@eso.org
