ALMA image of the disc around the young star TW Hydrae
ALMA image of the planet-forming disc around the young, Sun-like star TW Hydrae
Inner region of the TW Hydrae protoplanetary disc as imaged by ALMA
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ALMA image of the disc around the young star TW Hydrae
Evidence for planet formation in Earth-like orbit around young star
This new image from the Atacama Large
Millimeter/submillimeter Array (ALMA) shows the finest detail ever seen
in the planet-forming disc around the nearby Sun-like star TW Hydrae. It
reveals a tantalising gap at the same distance from the star as the
Earth is from the Sun, which may mean that an infant version of our home
planet, or possibly a more massive super-Earth, is beginning to form
there.
The star TW Hydrae
is a popular target of study for astronomers because of its proximity
to Earth (only about 175 light-years away) and its status as an infant
star (about 10 million years old). It also has a face-on orientation as
seen from Earth. This gives astronomers a rare, undistorted view of the
complete protoplanetary disc around the star.
"Previous studies with optical and radio telescopes
confirm that TW Hydrae hosts a prominent disc with features that
strongly suggest planets are beginning to coalesce," said Sean Andrews with the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts, USA and lead author on a paper published today in the Astrophysical Journal Letters. "The
new ALMA images show the disc in unprecedented detail, revealing a
series of concentric dusty bright rings and dark gaps, including
intriguing features that may indicate that a planet with an Earth-like
orbit is forming there."
Other pronounced gaps that show up in the new images are
located three billion and six billion kilometres from the central star,
similar to the average distances from the Sun to Uranus and Pluto in the
Solar System.
They too are likely to be the results of particles that
came together to form planets, which then swept their orbits clear of
dust and gas and shepherded the remaining material into well-defined
bands.
For the new TW Hydrae observations, astronomers imaged the
faint radio emission from millimetre-sized dust grains in the disc,
revealing details on the order of the distance between the Earth and the
Sun (about 150 million kilometres). These detailed observations were
made possible with ALMA’s
high-resolution, long-baseline configuration. When ALMA's dishes are at
their maximum separation, up to 15 kilometres apart, the telescope is
able to resolve finer details. "This is the highest spatial
resolution image ever of a protoplanetary disc from ALMA, and that won't
be easily beaten in the future!" said Andrews [1].
"TW Hydrae is quite special. It is the nearest known
protoplanetary disc to Earth and it may closely resemble the Solar
System when it was only 10 million years old," adds co-author David Wilner, also with the Harvard-Smithsonian Center for Astrophysics.
Earlier ALMA observations of another system, HL Tauri,
show that even younger protoplanetary discs — a mere 1 million years
old — can display similar signatures of planet formation. By studying
the older TW Hydrae disc, astronomers hope to better understand the
evolution of our own planet and the prospects for similar systems
throughout the Milky Way.
The astronomers now want to find out how common these kinds of
features are in discs around other young stars and how they might change
with time or environment.
Notes
[1] The angular resolution of the images of HL Tauri was similar to these new observations, but as TW Hydrae is much closer to Earth, finer details can be seen.
More Information
This research was presented in a paper "Ringed Substructure
and a Gap at 1 AU in the Nearest Protoplanetary Disk", by S.M. Andrews
et al., appearing in the Astrophysical Journal Letters.
The team is composed of Sean M. Andrews
(Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts,
USA), David J. Wilner (Harvard-Smithsonian Center for Astrophysics,
Cambridge, Massachusetts, USA) , Zhaohuan Zhu (Princeton University,
Princeton, New Jersey, USA), Tilman Birnstiel (Max-Planck-Institut für
Astronomie, Heidelberg, Germany), John M. Carpenter (Joint ALMA
Observatory, Santiago, Chile), Laura M. Peréz (Max-Planck-Institut für
Radioastronomie, Bonn, Germany), Xue-Ning Bai (Harvard-Smithsonian
Center for Astrophysics, Cambridge, Massachusetts, USA), Karin I. Öberg
(Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts,
USA), A. Meredith Hughes (Wesleyan University, Van Vleck Observatory,
Middletown, USA), Andrea Isella (Rice University, Houston, Texas, USA)
and Luca Ricci (Harvard-Smithsonian Center for Astrophysics, Cambridge,
Massachusetts, USA).
The Atacama Large Millimeter/submillimeter Array (ALMA), an international astronomy facility, is a partnership of ESO, the U.S. National Science Foundation (NSF) and the National Institutes of Natural Sciences (NINS) of Japan in cooperation with the Republic of Chile. ALMA is funded by ESO on behalf of its Member States, by NSF in cooperation with the National Research Council of Canada (NRC) and the National Science Council of Taiwan (NSC) and by NINS in cooperation with the Academia Sinica (AS) in Taiwan and the Korea Astronomy and Space Science Institute (KASI).
ALMA construction and operations are led by ESO on behalf
of its Member States; by the National Radio Astronomy Observatory
(NRAO), managed by Associated Universities, Inc. (AUI), on behalf of
North America; and by the National Astronomical Observatory of Japan
(NAOJ) on behalf of East Asia. The Joint ALMA Observatory (JAO) provides
the unified leadership and management of the construction,
commissioning and operation of ALMA.
ESO is the foremost intergovernmental astronomy
organisation in Europe and the world’s most productive ground-based
astronomical observatory by far. It is supported by 16 countries:
Austria, Belgium, Brazil, the Czech Republic, Denmark, France, Finland,
Germany, Italy, the Netherlands, Poland, Portugal, Spain, Sweden,
Switzerland and the United Kingdom, along with the host state of Chile.
ESO carries out an ambitious programme focused on the design,
construction and operation of powerful ground-based observing facilities
enabling astronomers to make important scientific discoveries. ESO also
plays a leading role in promoting and organising cooperation in
astronomical research. ESO operates three unique world-class observing
sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO
operates the Very Large Telescope, the world’s most advanced
visible-light astronomical observatory and two survey telescopes. VISTA
works in the infrared and is the world’s largest survey telescope and
the VLT Survey Telescope is the largest telescope designed to
exclusively survey the skies in visible light. ESO is a major partner in
ALMA, the largest astronomical project in existence. And on Cerro
Armazones, close to Paranal, ESO is building the 39-metre European
Extremely Large Telescope, the E-ELT, which will become “the world’s
biggest eye on the sky”.
Links
Contacts
Sean M. Andrews
Harvard-Smithsonian Center for Astrophysics
Cambridge, Massachusetts, USA
Email: sandrews@cfa.harvard.edu
Charles Blue
NRAO Public Information Officer
Tel: +1 434 296-0314
Email: cblue@nrao.edu
Richard Hook
ESO Public Information Officer
Garching bei München, Germany
Tel: +49 89 3200 6655
Cell: +49 151 1537 3591
Email: rhook@eso.org
