By Dr Nandkumar Kamat
Drake’s equation, Car Sagan’s dreams may come true - going by the rate of discovery of planets which lie far, far beyond our own solar system. It shows that there is nothing special about our solar system. As on August 24 there were 488 extrasolar planets.
If NASA’s planet hunter Kepler mission’s work confirms more planets then by end of this year this number may reach 1000. Elsewhere in our own Milky Way galaxy there would be thousands of solar systems and millions of planets. But it is the first time a discovery of a large solar system has been made around a star named HD 1018. This is our stepping stone for exosolar system research. It is the most exciting news this month.
An exciting age in astronomy is awaiting the would-be-engineers and technologists. Ten years from now the world would be discussing many new and amazing solar systems, a few like ours and many which would confound us. The race to be the first discoverer of an earth like planet with signs of organic life is heating up. The young engineers would turn planet hunters. They would design, fabricate and use highly precise instruments to detect exoplanets. Those who switch over to astronomy may even detect Earth like planets.
A planet is defined as an object orbiting a star that is massive enough both to have achieved an almost spherical shape and to have cleared the rotating disc of dense gas, known as the protoplanetary disc, that surrounds a newly formed star. The first detection of an exoplanet occurred in 1992 when the astrophysicists Aleksander Wolszczan and Dale Frail discovered three exoplanets. They were found in an unexpected environment, orbiting the pulsar PSR1257+12. Since 1995, this area of astronomy has become a very dynamic research field using a host of techniques. Nowadays six investigative tools are used to spot hidden exoplanets - Direct detection, Imaging, Indirect detection, Radial velocity tracking, Astrometry, Pulsar timing, Transits and Gravitational microlensing.
In what can be said as triumph of high precision optical technology - HARPS, the High Accuracy Radial velocity Planet Searcher, at the European Southern Observatory (ESO) La Silla 3.6m telescope dedicated to the discovery of extrasolar planets discovered a planetary system containing at least five planets, orbiting the Sun-like star HD 1018. HARPS is a fibre-fed high resolution echelle spectrograph. The astronomers working on (ESO)’s La silla 3.6 metre telescope in Chile were excited to find evidence that two other planets may be present, one of which would have the lowest mass ever found. This would make the system similar to our Solar System in terms of the number of planets (seven as compared to the Solar System’s eight planets). Furthermore, the team also found evidence that the distances of the planets from their star follow a regular pattern, as also seen in our Solar System.
Astronomer Christophe Lovis - who wrote a paper (serious students and readers can download it free from http://www.eso.org/public/archives/releases/sciencepapers/eso1035/eso103...) to declare the historic discovery told the press - "We have found what is most likely the system with the most planets yet discovered. This remarkable discovery also highlights the fact that we are now entering a new era in exoplanet research: the study of complex planetary systems and not just of individual planets. Studies of planetary motions in the new system reveal complex gravitational interactions between the planets and give us insights into the long-term evolution of the system."
He writes in the paper - "The increasing number of multi-planet systems containing at least three known planets greatly extends the possibilities to study the orbital architectures of extrasolar planetary systems and compare them to our Solar System. Although there are already 15 systems with at least three planets as of May 2010, one should recognise that our knowledge of many of them is still highly incomplete due to observational biases."
The paper concludes - "With the advent of the space observatories CoRoT and Kepler, low-mass planets have also become accessible to transit searches. According to early announcements, the Kepler mission will soon confirm what radial velocity surveys are already starting to find: rocky/icy planets are very common in the Universe. The combination of both techniques is likely to bring rapid progress in our understanding of the formation and composition of this population. The HD 10180 system represents an interesting example of the various outcomes of planet formation. No massive gas giant was formed, but instead a large number of still relatively massive objects survived, and migrated to the inner regions. Building a significant sample of such low-mass systems will show what are the relative influences of the different physical processes at play during planet formation and evolution."
International Astronomical Union (IAU) is still evolving nomenclature for this new class of planets beyond our solar system. With the recent discovery of new solar system and confirmation of 15 solar systems beyond our own, many new questions would be asked. Our solar system was formed about five billion years ago and life on earth evolved some four billion years ago. Earth has organic life because it is within ‘habitable zone’, not too close, nor too far from Sun. What would the new solar system look like? Would there be a ‘habitable zone’ to support Earth like planets? How many such Earth-like planets would be detected?
As history of life on earth shows a period of one billion years is required for life to arise. So even if Earth like planets get discovered with Earth like atmosphere, what would be their age? Or organic evolution would follow a different trajectory, slower or faster on these extrasolar Earths in other solar systems? How the central star would influence the life processes on these new Earths? Our astronomy books are getting slowly outdated. The new solar system is a challenge for astronomers. More such puzzling solar systems are likely to be discovered by NASA’s Kepler mission. NASA had scheduled a special press conference on August 26 on new discoveries from Kepler and readers can find those details from Kepler mission website- http://kepler.nasa.gov/. It is not easy to get a clear photograph of Earth like planets from a huge distance, so we would have to wait for a few more years for precision technology to improve substantially.
