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Planet Found in the Habitable Zone of our Neighboring Star System

 A version of this article is also available for young scientists! Read it at Spacescoop

The planet, a world just a little bigger than Earth, orbits the red dwarf star Proxima Centauri in just 11.2 days, close enough that liquid water may exist on the surface of the planet. Proxima Centauri is the faintest member of a triple star system Alpha Centauri, which is the closest star to the Earth after the Sun, lying just 4.37 light years away. Earlier this year, Las Cumbres Observatory (LCO) scientists joined an international team of astronomers for the Pale Red Dot Campaign to closely observe Proxima Centauri, which led to this landmark discovery. Their findings will be published in the journal Nature on 25 August 2016.

Artist's impression of the surface of Proxima Centauri b

An artist’s impression shows a view of the surface of the planet Proxima b orbiting the red dwarf star Proxima Centauri, the closest star to the Solar System. The double star Alpha Centauri AB also appears in the image to the upper-right of Proxima itself. Proxima b is a little more massive than the Earth and orbits in the habitable zone around Proxima Centauri, where the temperature is suitable for liquid water to exist on its surface.

Credit: ESO/M. Kornmesser

The Pale Red Dot team, led by Guillem Anglada-Escudé, from Queen Mary University of London, simultaneously monitored Proxima Centauri over the course of about 3 months with an array of cutting edge telescopes and instruments.  The presence of the planet was given away by tiny back and forth movements of the star caused by the gravitational pull of the orbiting planet.  This caused a small, but periodic, Doppler shift in the color of the light from the star that was detected by the HARPS spectrograph on the ESO 3.6-metre telescope at La Silla in Chile, and used to measure the star’s radial velocity.  Careful analysis showed that they indicated the presence of a planet with a mass at least 1.3 times that of the Earth, orbiting about 7 million kilometres from Proxima Centauri — only 5% of the Earth-Sun distance.

But this signal by itself was not enough to convince the astronomers.  Red dwarfs like Proxima Centauri are active stars and can vary in ways that would mimic the presence of a planet.   To rule this out, the team simultaneously monitored the changing brightness of the star using the Las Cumbres Observatory (LCO) telescope network, headquartered in Goleta, CA, as well as other facilities such as the ASH2 telescope at the San Pedro de Atacama Celestial Explorations Observatory in Chile. These data made it possible to reliably exclude radial velocity measurements taken when the star was flaring from the final analysis, proving that the signal was indeed due to an orbiting planet.  

The LCO observations were conducted by LCO-alumnus, Dr. Yiannis Tsapras, who now works at the University of Heidelberg, Germany.  Yiannis writes: “I used the LCOGT network of telescopes to  monitor Proxima's stellar activity throughout the campaign and analysed the observations. Since the radial velocity signal is so close to our sensitivity limits, we had to ensure that it was not due to stellar activity. A combined analysis of the two data sets showed without question that the planetary signal was not due to the activity of the star.”

Although the planet lies much closer to the star than Earth does to the Sun, the cooler temperature of the star means that the planet actually falls with the Habitable Zone, meaning that liquid water may exist on its surface.  It does not necessarily follow that life exists there however, as the planet may also receive intense ultraviolet and X-ray flares from its host star.  

This discovery will be the beginning of extensive further observations, both with current instruments and with the next generation of giant telescopes such as the Giant Magellan Telescope (GMT), the Thirty Meter Telescope (TMT) and the European Extremely Large Telescope (E-ELT). Proxima b will be a prime target for the hunt for evidence of life elsewhere in the Universe. Indeed, the Alpha Centauri system is also the target of humankind’s first attempt to travel to another star system, the StarShot project.

Guillem Anglada-Escudé concludes: "Many exoplanets have been found and many more will be found, but searching for the closest potential Earth-analog and succeeding has been the experience of a lifetime for all of us. Many people’s stories and efforts have converged on this discovery. The result is also a tribute to all of them. The search for life on Proxima b comes next..."

Based on ESO press release (Includes additional images and videos).

Read the Space Scoop of this story, Could Aliens Be Closer Than We Thought?, written in partnership with Universe Awareness.

Links

Contacts

In Santa Barbara, CA area:
Dr. Rachel Street, Las Cumbres Observatory Project Scientist

Dr. Todd Boroson, Las Cumbres Observatory President & Observatory Director

6740 Cortona Drive, Suite 102, Goleta, CA 93117
Tel: 805 880 1631 (Rachel) 805 880 1618 (Todd)
Email: rstreet@lcogt.net, tboroson@lcogt.net

Guillem Anglada-Escudé (Lead Scientist)
Queen Mary University of London
London, United Kingdom
Tel: +44 (0)20 7882 3002
Email: g.anglada@qmul.ac.uk

Yiannis Tsapras (Scientist)
Astronomisches Rechen-Institut, Zentrum für Astronomie der Universität Heidelberg
Heidelberg, Germany
Tel: +49 6221 54-181
Email: ytsapras@ari.uni-heidelberg.de

Pedro J. Amado (Scientist)
Instituto de Astrofísica de Andalucía - Consejo Superior de Investigaciones Cientificas (IAA/CSIC)
Granada, Spain
Tel: +34 958 23 06 39
Email: pja@iaa.csic.es

Ansgar Reiners (Scientist)
Institut für Astrophysik, Universität Göttingen
Göttingen, Germany
Tel: +49 551 3913825
Email: ansgar.reiners@phys.uni-goettingen.de

James S. Jenkins (Scientist)
Departamento de Astronomia, Universidad de Chile
Santiago, Chile
Tel: +56 (2) 2 977 1125
Email: jjenkins@das.uchile.cl

Michael Endl (Scientist)
McDonald Observatory, The University of Texas at Austin
Austin, Texas, USA
Tel: +1 512 471 8312
Email: mike@astro.as.utexas.edu

Richard Hook (Coordinating Public Information Officer)
ESO Public Information Officer
Garching bei München, Germany
Tel: +49 89 3200 6655
Cell: +49 151 1537 3591
Email: proxima@eso.org

Martin Archer (Public Information Officer)
Queen Mary University of London
London, United Kingdom
Tel: +44 (0) 20 7882 6963
Email: m.archer@qmul.ac.uk

Silbia López de Lacalle (Public Information Officer)
Instituto de Astrofísica de Andalucía
Granada, Spain
Tel: +34 958 23 05 32
Email: silbialo@iaa.es

Romas Bielke (Public Information Officer)
Georg August Universität Göttingen
Göttingen, Germany
Tel: +49 551 39-12172
Email: Romas.Bielke@zvw.uni-goettingen.de

Natasha Metzler (Public Information Officer)
Carnegie Institution for Science
Washington DC, USA
Tel: +1 (202) 939 1142
Email: nmetzler@carnegiescience.edu

David Azocar (Public Information Officer)
Departamento de Astronomia, Universidad de Chile
Santiago, Chile
Email: dazocar@das.uchile.cl

Rebecca Johnson (Public Information Officer)
McDonald Observatory, The University of Texas at Austin
Austin, Texas, USA
Tel: +1 512 475 6763
Email: rjohnson@astro.as.utexas.edu

Hugh Jones (Scientist)
University of Hertfordshire
Hatfield, United Kingdom
Tel: +44 (0)1707 284426
Email: h.r.a.jones@herts.ac.uk

Jordan Kenny (Public Information Officer)
University of Hertfordshire
Hatfield, United Kingdom
Tel: +44 1707 286476
Cell: +44 7730318371
Email: j.kenny@herts.ac.uk




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