The jewel in Orion’s sword
Videos
Panning across a deep infrared image of the Orion Nebula
Zooming into a deep infrared image of the Orion Nebula
Cross-fade between visible and infrared light images of the Orion Nebula
VLT infrared images reveal unexpected horde of low-mass objects
ESO’s HAWK-I infrared instrument on the
Very Large Telescope (VLT) in Chile has been used to peer deeper into
the heart of Orion Nebula than ever before. The spectacular picture
reveals about ten times as many brown dwarfs and isolated planetary-mass
objects than were previously known. This discovery poses challenges for
the widely accepted scenario for Orion’s star formation history.
An international team has made use of the power of the HAWK-I infrared instrument on ESO’s Very Large Telescope (VLT) to produce the deepest and most comprehensive view of the Orion Nebula [1] to date. Not only has this led to an image of spectacular beauty, but it has revealed a great abundance of faint brown dwarfs
and isolated planetary-mass objects. The very presence of these
low-mass bodies provides an exciting insight into the history of star
formation within the nebula itself.
The famous Orion Nebula spans about 24 light-years within the constellation of Orion,
and is visible from Earth with the naked eye, as a fuzzy patch in
Orion’s sword. Some nebulae, like Orion, are strongly illuminated by
ultraviolet radiation from the many hot stars born within them, such
that the gas is ionised and glows brightly.
The relative proximity of the Orion Nebula [2]
makes it an ideal testbed to better understand the process and history
of star formation, and to determine how many stars of different masses
form.
Amelia Bayo (Universidad de Valparaíso, Valparaíso, Chile;
Max-Planck Institut für Astronomie, Königstuhl, Germany), a co-author of
the new paper and member of the research team, explains why this is
important: "Understanding how many low-mass objects are found in the
Orion Nebula is very important to constrain current theories of star
formation. We now realise that the way these very low-mass objects form
depends on their environment."
This new image has caused excitement because it reveals a
unexpected wealth of very-low-mass objects, which in turn suggests that
the Orion Nebula may be forming proportionally far more low-mass objects
than closer and less active star formation regions.
Astronomers count up how many objects of different masses
form in regions like the Orion Nebula to try to understand the
star-formation process [3].
Before this research the greatest number of objects were found with
masses of about one quarter that of our Sun. The discovery of a plethora
of new objects with masses far lower than this in the Orion Nebula has
now created a second maximum at a much lower mass in the distribution of
star counts.
These observations also hint tantalisingly that the number
of planet-sized objects might be far greater than previously thought.
Whilst the technology to readily observe these objects does not exist
yet, ESO’s future European Extremely Large Telescope (E-ELT), scheduled to begin operations in 2024, is designed to pursue this as one of its goals.
Lead scientist Holger Drass (Astronomisches Institut,
Ruhr-Universität Bochum, Bochum, Germany; Pontificia Universidad
Católica de Chile, Santiago, Chile) enthuses: “Our result feels to
me like a glimpse into a new era of planet and star formation science.
The huge number of free-floating planets at our current observational
limit is giving me hope that we will discover a wealth of smaller
Earth-sized planets with the E-ELT.”
Notes
[1] Nebulae such as the famous one in Orion are also known
as H II regions to indicate that they contain ionised hydrogen. These
immense clouds of interstellar gas are sites of star formation
throughout the Universe.
[3] This information is used to create something called the Initial Mass Function
(IMF) — a way of describing how many stars of different masses make up a
stellar population at its birth. This provides an insight into the
stellar population’s origins. In other words, determining an accurate
IMF, and having a solid theory to explain the origin of the IMF is of
fundamental importance in the study of star formation.
More Information
This research was presented in a paper entitled “The
bimodal initial mass function in the Orion Nebula Cloud”, by H. Drass et
al., published in Monthly Notices of the Royal Astronomical Society.
The team is composed of H. Drass (Astronomisches Institut,
Ruhr-Universität Bochum, Bochum, Germany; Pontificia Universidad
Católica de Chile, Santiago, Chile), M. Haas (Astronomisches Institut,
Ruhr-Universität Bochum, Bochum, Germany), R. Chini (Astronomisches
Institut, Ruhr-Universität Bochum, Bochum, Germany; Universidad Católica
del Norte, Antofagasta, Chile), A. Bayo (Universidad de Valparaíso,
Valparaíso, Chile; Max-Planck Institut für Astronomie, Königstuhl,
Germany) , M. Hackstein (Astronomisches Institut, Ruhr-Universität
Bochum, Bochum, Germany), V. Hoffmeister (Astronomisches Institut,
Ruhr-Universität Bochum, Bochum, Germany), N. Godoy (Universidad de
Valparaíso, Valparaíso, Chile) and N. Vogt (Universidad de Valparaíso,
Valparaíso, Chile).
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
Holger Drass
Pontificia Universidad Católica de Chile / Astronomisches Institut, Ruhr-Universität Bochum
Santiago / Bochum, Chile / Germany
Cell: +491714890578
Email: hdrass@aiuc.puc.cl
Amelia Bayo
Universidad de Valparaíso / Max-Planck Institut für Astronomie
Valparaíso / Königstuhl, Chile / Germany
Cell: +56 981381715
Email: amelia.bayo@uv.cl
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
