Artist’s impression of stars born in winds from supermassive black holes
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ESOcast 101 Light: Stars found in black hole blasts
Artist’s impression of stars born in winds from supermassive black holes
ESO’s VLT spots brand-new type of star formation
Observations using ESO’s Very Large
Telescope have revealed stars forming within powerful outflows of
material blasted out from supermassive black holes at the cores of
galaxies. These are the first confirmed observations of stars forming in
this kind of extreme environment. The discovery has many consequences
for understanding galaxy properties and evolution. The results are
published in the journal Nature.
A UK-led group of European astronomers used the MUSE and X-shooter instruments on the Very Large Telescope (VLT) at ESO’s Paranal Observatory in Chile to study an ongoing collision between two galaxies, known collectively as IRAS F23128-5919,
that lie around 600 million light-years from Earth. The group observed
the colossal winds of material — or outflows — that originate near the
supermassive black hole at the heart of the pair’s southern galaxy, and
have found the first clear evidence that stars are being born within
them [1].
Such galactic outflows are driven by the huge energy output from the active and turbulent centres of galaxies. Supermassive black holes
lurk in the cores of most galaxies, and when they gobble up matter they
also heat the surrounding gas and expel it from the host galaxy in
powerful, dense winds [2].
“Astronomers have thought for a while that conditions within
these outflows could be right for star formation, but no one has seen it
actually happening as it’s a very difficult observation,” comments team leader Roberto Maiolino from the University of Cambridge. “Our results are exciting because they show unambiguously that stars are being created inside these outflows.”
The group set out to study stars in the outflow directly, as well as
the gas that surrounds them. By using two of the world-leading VLT spectroscopic
instruments, MUSE and X-shooter, they could carry out a very detailed
study of the properties of the emitted light to determine its source.
Radiation from young stars is known to cause nearby gas clouds to
glow in a particular way. The extreme sensitivity of X-shooter allowed
the team to rule out other possible causes of this illumination,
including gas shocks or the active nucleus of the galaxy.
The group then made an unmistakable direct detection of an infant stellar population in the outflow [3].
These stars are thought to be less than a few tens of millions of years
old, and preliminary analysis suggests that they are hotter and
brighter than stars formed in less extreme environments such as the
galactic disc.
As further evidence, the astronomers also determined the motion and
velocity of these stars. The light from most of the region’s stars
indicates that they are travelling at very large velocities away from
the galaxy centre — as would make sense for objects caught in a stream
of fast-moving material.
Co-author Helen Russell (Institute of Astronomy, Cambridge, UK) expands: “The
stars that form in the wind close to the galaxy centre might slow down
and even start heading back inwards, but the stars that form further out
in the flow experience less deceleration and can even fly off out of
the galaxy altogether.”
The discovery provides new and exciting information that could better
our understanding of some astrophysics, including how certain galaxies
obtain their shapes [4]; how intergalactic space becomes enriched with heavy elements [5]; and even from where unexplained cosmic infrared background radiation may arise [6].
Maiolino is excited for the future: “If star formation is really
occurring in most galactic outflows, as some theories predict, then this
would provide a completely new scenario for our understanding of galaxy
evolution.”
More Information
This research was presented in a paper entitled “Star formation in a galactic outflow” by Maiolino et al., to appear in the journal Nature on 27 March 2017.
The team is composed of R. Maiolino (Cavendish Laboratory; Kavli Institute for Cosmology, University of Cambridge, UK), H.R. Russell (Institute of Astronomy, Cambridge, UK), A.C. Fabian (Institute of Astronomy, Cambridge, UK), S. Carniani (Cavendish Laboratory; Kavli Institute for Cosmology, University of Cambridge, UK), R. Gallagher (Cavendish Laboratory; Kavli Institute for Cosmology, University of Cambridge, UK), S. Cazzoli (Departamento de Astrofisica-Centro de Astrobiología, Madrid, Spain), S. Arribas (Departamento de Astrofisica-Centro de Astrobiología, Madrid, Spain), F. Belfiore ((Cavendish Laboratory; Kavli Institute for Cosmology, University of Cambridge, UK), E. Bellocchi (Departamento de Astrofisica-Centro de Astrobiología, Madrid, Spain), L. Colina (Departamento de Astrofisica-Centro de Astrobiología, Madrid, Spain), G. Cresci (Osservatorio Astrofisico di Arcetri, Firenze, Italy), W. Ishibashi (Universität Zürich, Zürich, Switzerland), A. Marconi (Università di Firenze, Italy; Osservatorio Astrofisico di Arcetri, Firenze, Italy), F. Mannucci (Osservatorio Astrofisico di Arcetri, Firenze, Italy), E. Oliva (Osservatorio Astrofisico di Arcetri, Firenze, Italy), and E. Sturm (Max-Planck-Institut für Extraterrestrische Physik, Garching, Germany).
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”.
This research was presented in a paper entitled “Star formation in a galactic outflow” by Maiolino et al., to appear in the journal Nature on 27 March 2017.
The team is composed of R. Maiolino (Cavendish Laboratory; Kavli Institute for Cosmology, University of Cambridge, UK), H.R. Russell (Institute of Astronomy, Cambridge, UK), A.C. Fabian (Institute of Astronomy, Cambridge, UK), S. Carniani (Cavendish Laboratory; Kavli Institute for Cosmology, University of Cambridge, UK), R. Gallagher (Cavendish Laboratory; Kavli Institute for Cosmology, University of Cambridge, UK), S. Cazzoli (Departamento de Astrofisica-Centro de Astrobiología, Madrid, Spain), S. Arribas (Departamento de Astrofisica-Centro de Astrobiología, Madrid, Spain), F. Belfiore ((Cavendish Laboratory; Kavli Institute for Cosmology, University of Cambridge, UK), E. Bellocchi (Departamento de Astrofisica-Centro de Astrobiología, Madrid, Spain), L. Colina (Departamento de Astrofisica-Centro de Astrobiología, Madrid, Spain), G. Cresci (Osservatorio Astrofisico di Arcetri, Firenze, Italy), W. Ishibashi (Universität Zürich, Zürich, Switzerland), A. Marconi (Università di Firenze, Italy; Osservatorio Astrofisico di Arcetri, Firenze, Italy), F. Mannucci (Osservatorio Astrofisico di Arcetri, Firenze, Italy), E. Oliva (Osservatorio Astrofisico di Arcetri, Firenze, Italy), and E. Sturm (Max-Planck-Institut für Extraterrestrische Physik, Garching, Germany).
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
Cavendish Laboratory, Kavli Institute for Cosmology
University of Cambridge, UK
Email: r.maiolino@mrao.cam.ac.uk
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
