Protoplanetary discs observed with SPHERE
Disc around the young star RX J1615
Disc around the star HD 97048
Disc around the star HD 135344B
ESO’s SPHERE instrument reveals protoplanetary discs being shaped by newborn planets
ESO’s SPHERE instrument reveals protoplanetary discs being shaped by newborn planets
Sharp new observations have revealed
striking features in planet-forming discs around young stars. The SPHERE
instrument, mounted on ESO’s Very Large Telescope, has made it possible
to observe the complex dynamics of young solar systems — including one
seen developing in real-time. The recently published results from three
teams of astronomers showcase SPHERE’s impressive capability to capture
the way planets sculpt the discs that form them — exposing the
complexities of the environment in which new worlds are formed.
Three teams of astronomers have made use of SPHERE, an advanced exoplanet-hunting instrument on the Very Large Telescope (VLT) at ESO’s Paranal Observatory, in order to shed light on the enigmatic evolution of fledgling planetary systems. The explosion in the number of known exoplanets in recent years has made the study of them one of the most dynamic fields in modern astronomy.
Today it is known that planets form from vast discs of gas and dust encircling newborn stars, known as protoplanetary discs.
These can extend for thousands of millions of kilometres. Over time,
the particles in these protoplanetary discs collide, combine and
eventually build up into planet-sized bodies. However, the finer details
of the evolution of these planet-forming discs remain mysterious.
SPHERE is a recent addition to the VLT’s array of instruments
and with its combination of novel technologies, it provides a powerful
method to directly image the fine details of protoplanetary discs [1]. The interaction
between protoplanetary discs and growing planets can shape the discs
into various forms: vast rings, spiral arms or shadowed voids. These are
of special interest as an unambiguous link between these structures and
the sculpting planets is yet to be found; a mystery astronomers are
keen to solve. Fortunately, SPHERE’s specialised capabilities make it
possible for research teams to observe these striking features of
protoplanetary discs directly.
For example, RX J1615 is a young star, which lies in the constellation of Scorpius,
600 light-years from Earth. A team led by the Jos de Boer, of Leiden
Observatory in the Netherlands, found a complex system of concentric
rings surrounding the young star, forming a shape resembling a titanic
version of the rings that encircle Saturn. Such an intricate sculpting
of rings in a protoplanetary disc has only been imaged a handful of
times before, and even more excitingly, the entire system seems to be
only 1.8 million years old. The disc shows hints of being shaped by
planets still in the process of formation.
The age of the newly detected protoplanetary disc makes RX
J1615 an outstanding system, as most other examples of protoplanetary
discs detected so far are relatively old or evolved. De Boer’s
unexpected result was quickly echoed by the findings of a team led by
Christian Ginski, also of Leiden Observatory. They observed the young
star HD 97048, located in the constellation of Chamaeleon, about 500
light-years from Earth. Through painstaking analysis, they found that
the juvenile disc around this star has also formed into concentric
rings. The symmetry of these two systems is a surprising result, as most
protoplanetary systems contain a multitude of asymmetrical spiral arms,
voids and vortexes. These discoveries significantly raise the number of
known systems with multiple highly symmetrical rings.
A particularly spectacular example of the more common
asymmetric disc was captured by a group of astronomers led by Tomas
Stolker of the Anton Pannekoek Institute for Astronomy, the Netherlands.
This disc surrounds the star HD 135344B, about 450 light-years away.
Although this star has been well-studied in the past, SPHERE allowed the
team to see the star’s protoplanetary disc in more detail than ever
before. The large central cavity and two prominent spiral arm-like
structures are thought to have been created by one or multiple massive protoplanets, destined to become Jupiter-like worlds.
In addition, four dark streaks, apparently shadows thrown
by the movement of material within HD 135344B's disc, were observed.
Remarkably, one of the streaks noticeably changed in the months between
observing periods: a rare example of observing planetary evolution occur
in real time, hinting at changes occurring in the inner disc regions
that can not be directly detected by SPHERE. As well as producing
beautiful images, these flickering shadows provide a unique way of
probing the dynamics of innermost disc regions.
As with the concentric rings found by de Boer and Ginski, these
observations by Stolker’s team prove that the complex and changing
environment of the discs surrounding young stars are still capable of
producing surprising new discoveries. By building an impressive body of
knowledge about these protoplanetary discs, these teams are stepping
closer to understanding how planets shape the discs that form them — and
therefore understanding planet formation itself.
Notes
[1] SPHERE had first light in June 2014. The instrument uses advanced adaptive optics to remove atmospheric distortion, a coronagraph to block most of the light from the central star and a combination of differential imaging and polarimetry to isolate the light from features in the disc.
More Information
The research of de Boer, Ginski and Stolker and their colleagues in the SPHERE consortium is now accepted for publication in the journal Astronomy and Astrophysics. Their papers are entitled: "Direct detection of scattered light gaps in the transitional disk around HD 97048 with VLT/SPHERE"; "Shadows cast on the transition disk of HD 135344B: Multi-wavelength VLT/SPHERE polarimetric differential imaging", and "Multiple rings in the transition disk and companion candidates around RX J1615.3-3255: High contrast imaging with VLT/SPHERE". All three of papers have been created in the framework of the SPHERE GTO program, led by Carsten Dominik, University of Amsterdam.
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
Tomas Stolker
Anton Pannekoek Institute for Astronomy
Amsterdam, the Netherlands
Tel: +3120525 8152
Email: T.Stolker@uva.nl
Jos de Boer
Leiden University
Leiden, the Netherlands
Tel: +31715278139
Email: deboer@strw.leidenuniv.nl
Christian Ginski
Leiden University
Leiden, the Netherlands
Tel: +31715278139
Email: ginski@strw.leidenuniv.nl
Richard Hook
ESO Public Information Officer
Garching bei München, Germany
Tel: +49 89 3200 6655
Cell: +49 151 1537 3591
Email: rhook@eso.org
Notes
[1] SPHERE had first light in June 2014. The instrument uses advanced adaptive optics to remove atmospheric distortion, a coronagraph to block most of the light from the central star and a combination of differential imaging and polarimetry to isolate the light from features in the disc.
More Information
The research of de Boer, Ginski and Stolker and their colleagues in the SPHERE consortium is now accepted for publication in the journal Astronomy and Astrophysics. Their papers are entitled: "Direct detection of scattered light gaps in the transitional disk around HD 97048 with VLT/SPHERE"; "Shadows cast on the transition disk of HD 135344B: Multi-wavelength VLT/SPHERE polarimetric differential imaging", and "Multiple rings in the transition disk and companion candidates around RX J1615.3-3255: High contrast imaging with VLT/SPHERE". All three of papers have been created in the framework of the SPHERE GTO program, led by Carsten Dominik, University of Amsterdam.
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
- Research paper by Jos de Boer et al.
- Research paper by Christian Ginski et al.
- Research paper by Tomas Stolker et al.
Contacts
Tomas Stolker
Anton Pannekoek Institute for Astronomy
Amsterdam, the Netherlands
Tel: +3120525 8152
Email: T.Stolker@uva.nl
Jos de Boer
Leiden University
Leiden, the Netherlands
Tel: +31715278139
Email: deboer@strw.leidenuniv.nl
Christian Ginski
Leiden University
Leiden, the Netherlands
Tel: +31715278139
Email: ginski@strw.leidenuniv.nl
Richard Hook
ESO Public Information Officer
Garching bei München, Germany
Tel: +49 89 3200 6655
Cell: +49 151 1537 3591
Email: rhook@eso.org
Source: ESO
