Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Double sun sunset no longer science fiction

24.01.2007
During the last decade, the discovery of planets around stars other than the Sun has revealed a variety of kinds of planets, orbits, and systems, often very different to our Solar System.

One of the most interesting examples are those of stars accompanied not only by planets, but also by other stars, making double "Sun" sunsets, and sunrises, no longer science fiction. A research team from the University of Jena (Germany) has recently made interesting discoveries at Calar Alto by performing a systematic search for such systems.

Since the discovery in 1995 of the first extrasolar planet around a normal star (51 Pegasi), it has become evident that there exists an unexpected diversity of planetary systems, most of them very different to our Solar System. First, it was found that there are many massive planets placed extremely close to their parent stars: the so-called "hot Jupiters". This is very different from what we observe in the Solar System, where massive planets are located far away from the Sun, and this finding required a revision of the theories of planetary formation. Second, it was shown that the process of planetary formation is not restricted to single stars as our Sun: indeed, under certain circumstances, it is possible to form planets around binary stars, which are a much more dynamically complex environment than our own Solar System.

A binary star is a physical system formed by two stars circling around their common center of mass. There is a wide diversity of such couples, often formed by stars of similar mass, but there are also may examples of binary systems with components of very different masses. The Star and Planet Formation subgroup of the Astrophysical Institute of the University of Jena (AIU) has recently been looking hard into candidate systems that might allow the existence of planets surrounding binary stars. Their search, carried out by Ralph Neuhäuser and Markus Mugrauer, makes use of the sharpest possible images of these stars and their immediate surroundings in order to identify faint neighbors (that could be potentially associated with the system). To get images of extreme sharpness it is necessary to compensate the blurring effect of the atmosphere (which make stars twinkle) and this can be achieved thanks to adaptive optics, or other techniques such as speckle imaging, both available at Calar Alto. The potential companions detected this way are later studied in detail to confirm their true physical association to the planet-hosting star, by discarding the possibility that they are simple chance alignments of unrelated objects at different distances.

Infrared images of the gamma Cephei system obtained from Calar alto on September the 11th (left) and 12th (right) 2006. The bright, A component would be located at the center of both images, but it has been digitally subtracted to reveal the position of the faint, B component, marked with an arrow.

One of their recent findings refers to a quite bright star, gamma Cephei (gamma Cephei), a star with a planet (gamma Cephei Ab) with a minimum mass 1.7 times that of planet Jupiter and with a period of around 3 years. From previous spectroscopic studies this star is known to also have a low-mass stellar companion (gamma Cephei B) orbiting the brighter component. This team has now been able to get the first direct images of the secondary star which allow to significantly improve the determination of physical parameters of the gamma Cephei system. The observations were obtained both with the Japanese telescope Subaru (placed at Mauna Kea, Hawaii), and with the instrument Omega-Cass attached to the 3.5 m telescope of Calar Alto (Spain). The observations at Mauna Kea were obtained by Misato Fukagawa (Nagoya University) in June 2006, and at Calar Alto by Markus Mugrauer and Tobias Schmidt (both AIU Jena) in September 2006.

The two stars in the gamma Cephei system are separated by an average distance only 20 times the distance from the Earth to the Sun making this system one of the closest planet hosting binary systems presently known. It is composed of the central bright subgiant star gamma Cephei A, which is more massive than our Sun (1.4 solar masses), the secondary star gamma Cephei B which is smaller than half the mass of the Sun (0.4 solar masses) and a planetary companion, circling the primary star.

Imagine a "Sun" and a failed "Sun" sunset

Another outstanding discovery by the same team using Calar Alto telescopes, is that of the companion to the star HD 3651. HD 3651 is a nearby faint, red star, known to have a sub-Saturn-mass planet. This team discovered that the very faint companion is in fact a cool brown dwarf, the first brown dwarf directly imaged as companion to an exoplanet host star. Observations performed with the instrument Omega-Cass at the 3.5 m telescope of Calar Alto in September 2006, helped to demonstrate the link between HD 3651 and this small substellar object (now called HD 3651 B), and to determine its physical characteristics. The faint companion of the planet host star HD 3651 is one of the coolest brown dwarfs presently known (effective temperature ranging between 500o and 600o C).

The same research team has used several instruments and telescopes to find faint companions to planet host stars. In the course of their campaigns, they have found secondary objects with masses from 0.5 to 0.075 the mass of the Sun, in the substellar-stellar mass border. Two companions turned out to be white dwarf stars, an evolved kind of object whose existence in planet-harboring systems implies new restrictions to the theories that explain the formation of planets.

Science fiction needs to catch up!

Joao Alves | alfa
Further information:
http://www.caha.es

More articles from Physics and Astronomy:

nachricht A 100-year-old physics problem has been solved at EPFL
23.06.2017 | Ecole Polytechnique Fédérale de Lausanne

nachricht Quantum thermometer or optical refrigerator?
23.06.2017 | National Institute of Standards and Technology (NIST)

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Can we see monkeys from space? Emerging technologies to map biodiversity

An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.

Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

Im Focus: Scientists develop molecular thermometer for contactless measurement using infrared light

Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine

Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

Quantum thermometer or optical refrigerator?

23.06.2017 | Physics and Astronomy

A 100-year-old physics problem has been solved at EPFL

23.06.2017 | Physics and Astronomy

Equipping form with function

23.06.2017 | Information Technology

VideoLinks
B2B-VideoLinks
More VideoLinks >>>