- Transit Search Finds Super-Neptune
- Smallest known exoplanet may actually be Earth-mass Long,
- Stretchy Carbon Nanotubes Could Make Space Elevators Possible
Transit Search Finds Super-NeptuneJanuary 20th, 2009
(PhysOrg.com) -- Astronomers at the Harvard-Smithsonian Center for Astrophysics have discovered a planet somewhat larger and more massive than Neptune orbiting a star 120 light-years from Earth. While Neptune has a diameter 3.8 times that of Earth and a mass 17 times Earth's, the new world (named HAT-P-11b) is 4.7 times the size of Earth and has 25 Earth masses.
HAT-P-11b was discovered because it passes directly in front of (transits) its parent star, thereby blocking about 0.4 percent of the star's light. This periodic dimming was detected by a network of small, automated telescopes known as "HATNet," which is operated by the Center in Arizona and Hawaii. HAT-P-11b is the 11th extrasolar planet found by HATNet, and the smallest yet discovered by any of the several transit search projects underway around the world.
Transit detections are particularly useful because the amount of dimming tells the astronomers how big the planet must be.
A number of Neptune-like planets have been found recently by radial velocity searches, but HAT-P-11b is only the second Neptune-like planet found to transit its star, thus permitting the precise determination of its mass and radius.
The newfound world orbits very close to its star, revolving once every 4.88 days. As a result, it is baked to a temperature of around 1100 degrees F. The star itself is about three-fourths the size of our Sun and somewhat cooler.
There are signs of a second planet in the HAT-P-11 system, but more radial velocity data are needed to confirm that and determine its properties.
Another team has located one other transiting super-Neptune, known as GJ436b, around a different star. It was discovered by a radial velocity search and later found to have transits.
HAT-P-11 is in the constellation Cygnus, which puts in it the field of view of NASA's upcoming Kepler spacecraft which would be able to find with the same transit technique the first Earth-like world orbiting a distant star..source
My comment: Awesome, right? So far most planets we see are Jupiter-like and Jupiter isn't exactly a place where you can find humanoids. But Neptune and smaller are other thing! I'm so happy!
Smallest known exoplanet may actually be Earth-mass
- 19 January 2009 by Stephen Battersby
The smallest planet around a normal star other than the Sun may be even smaller than first thought. A new analysis suggests the rocky body weighs just 1.4 Earths - less than half the original estimate.
In 2008, astronomers discovered a planet estimated to weigh just three Earth masses. Called MOA-2007-BLG-192-L b, it claimed the title of the lightest known exoplanet.
The planet was detected using a technique called microlensing, in which one star passes in front of another as seen from Earth.
Initially, the team believed that this host star was a brown dwarf. That suggested MOA-2007-BLG-192-L b weighed 3.3 Earths.
But more recent observations suggest the parent star is actually heavier than first thought - a type of star called a red dwarf, team member Jean-Philippe Beaulieu of the Paris Astrophysical Institute reported last week.
That suggests the planet weighs just 1.4 Earths. In size terms, that makes it a near twin of our own planet, closer in mass than any known planet except Venus.
The team plans to get more data on the parent star in April or May using the VLT in Chile.
If their analysis is confirmed, it is an unclear whether the tiny planet could host any life. Because its host is a very dim red dwarf, the planet is likely to be frozen.
However, if the planet boasts a thick, insulating hydrogen atmosphere, it could sustain a habitable surface temperature that might be able to support some life of some kind . source
My comment: As I promised, very exciting news. For me, what the coolest is not so much that this is one of the first planets with size comparable to that of our own planet. I just love the last sentence! People are finally realising that life is much more than we know. That we may find life even in places where we couldn't live without too much trouble. This is amaizng evolution. I'm so sure we're going to find them (or they-us) very very soon. Eh.
Long, Stretchy Carbon Nanotubes Could Make Space Elevators PossibleJanuary 23rd, 2009
(PhysOrg.com) -- Scientists from Cambridge University have developed a light, flexible, and strong type of carbon nanotube material that may bring space elevators closer to reality. Motivated by a $4 million prize from NASA, the scientists found a way to combine multiple separate nanotubes together to form long strands. Until now, carbon nanotubes have been too brittle to be formed into such long pieces.
NASA needs about 144,000 miles of nanotube to build one. In theory, a cable would extend 22,000 miles above the Earth to a station, which is the distance at which satellites remain in geostationary orbit. Due to the competing forces of the Earth's gravity and outward centrifugal pull, the elevator station would remain at that distance like a satellite. Then the cable would extend another 40,000 miles into space to a weighted structure for stability. An elevator car would be attached to the nanotube cable and powered into space along the track.
Space elevators could lift material at just one-fifth the cost of a rocket, since most of a rocket's energy is used simply to escape Earth's gravity.
Currently, the Cambridge team can make about 1 gram of the new carbon material per day, which can stretch to 18 miles in length. Alan Windle, professor of materials science at Cambridge, says that industrial-level production would be required to manufacture NASA's request for 144,000 miles of nanotube. Nevertheless, the web-like nanotube material is promising.
"The key thing is that the process essentially makes carbon into smoke, but because the smoke particles are long thin nanotubes, they entangle and hold hands," Windle said. "We are actually making elastic smoke, which we can then wind up into a fiber."
Windle and his colleagues presented their results last month at a conference in Luxembourg, which attracted hundreds of attendees from groups such as NASA and the European Space Agency. John Winter of EuroSpaceward, which organized the conference, thought the new material was a significant step.source
My comment: Nice, eh? Space elevators have always been one of our best hopes. Because the business with rockets and their engines and exhausts and everything is so tough. While if you can be lifted without them, that would be simply lovely. Because even if the elevator needs to be fuelled by a similar rocket, imagine how much of extra-cost will save from all the other parts the shuttle/rocket. And the trip might be even pleasant! That's quite something if you ask me.