“Currently the number of exoplanets stands at close to 600…”

[Image credit: ESO/M. Kornmesser].  As the BBC reported, astronomers using the HARPS spectrograph on the 3.6-metre telescope at the European Southern Observatory [ESO]’s La Silla Observatory in Chile recently announced the discovery of more than 50 new exoplanets orbiting nearby stars, including sixteen super-Earths.  It’s the subject of ESOcast 35: 50 New Exoplanets.

From the ESO science release

In the eight years since it started surveying stars like the Sun using the radial velocity technique HARPS has been used to discover more than 150 new planets. About two thirds of all the known exoplanets with masses less than that of Neptune [4] were discovered by HARPS. These exceptional results are the fruit of several hundred nights of HARPS observations [5].

Working with HARPS observations of 376 Sun-like stars, astronomers have now also much improved the estimate of how likely it is that a star like the Sun is host to low-mass planets (as opposed to gaseous giants). They find that about 40% of such stars have at least one planet less massive than Saturn. The majority of exoplanets of Neptune mass or less appear to be in systems with multiple planets.

With upgrades to both hardware and software systems in progress, HARPS is being pushed to the next level of stability and sensitivity to search for rocky planets that could support life. Ten nearby stars similar to the Sun were selected for a new survey. These stars had already been observed by HARPS and are known to be suitable for extremely precise radial velocity measurements. After two years of work, the team of astronomers has discovered five new planets with masses less than five times that of Earth.

These planets will be among the best targets for future space telescopes to look for signs of life in the planet’s atmosphere by looking for chemical signatures such as evidence of oxygen,” explains Francesco Pepe (Geneva Observatory, Switzerland), the lead author of one of the recent papers.

One of the recently announced newly discovered planets, HD 85512 b, is estimated to be only 3.6 times the mass of the Earth [6] and is located at the edge of the habitable zone — a narrow zone around a star in which water may be present in liquid form if conditions are right [7].

Here’s a close-up of the star in question,  HD 85512. [Image credit: ESO and Digitized Sky Survey 2. Acknowledgment: Davide De Martin]

And they’re not the only ones looking for exo-planets, Nasa’s orbiting Kepler observatory has identifed 1,235 planetary candidates – and 54 candidates within the habitable zone since its launch in March 2009.

From the notes to the ESO science release

Currently the number of exoplanets stands at close to 600. In addition to exoplanets found using radial velocity techniques, more than 1200 exoplanet candidates have been found by NASA’s Kepler mission using an alternative method — searching for the slight drop in the brightness of a star as a planet passes in front of it (transits) and blocks some of the light. The majority of planets discovered by this transit method are very distant from us. But, in contrast, the planets found by HARPS are around stars close to the Sun. This makes them better targets for many kinds of additional follow-up observations.

And a reminder of a quote from one of Those [Royal Society] Guys, Isaac Newton contemporary, and long-term rival, Robert Hooke.  From the preface to his 1665 publication Micrographia

‘Tis not unlikely, but that there may be yet invented several other helps for the eye, as much exceeding those already found, as those do the bare eye, such as we may perhaps be able to discover living Creatures in the Moon, or other Planets, the figures of the compounding Particles of matter, and the particular Schematisms and Textures of Bodies.

And, because I can, here’s the wondrous night sky above the ESO Very Large Telescope array [VLT], also in Chile.  [Video credit: ESO/S. Guisard (www.eso.org/~sguisard) ESO/José Francisco Salgado (josefrancisco.org)]

Finally, here’s another stunning image, taken by ESO Photo Ambassador Yuri Beletsky, of the sky above ESO’s VLT during the total lunar eclipse of 21 December 2010.  [Image credit: ESO/Y. Beletsky]

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