[meteorite-list] So many parent bodies, so few samples
http://www.space.com/scienceastronomy/070611_mm_planet_floodgates.html Trickle of Planet Discoveries Becomes a Flood By Jeanna Bryner Staff Writer posted: 11 June 2007 07:10 am ET Alien worlds, once hidden from knowledge, are now being discovered in droves, stunning astronomers with their unique features and sheer numbers. The discoveries are so common that more and more don't even get reported outside scientific circles. Take the announcement at the end of May of a massive planet, dubbed TrES-3, that zips around its star in an amazingly rapid 31 hours, giving the planet a 1.3-day year. Astronomers issued a press release, but you might not have heard about it because the discovery was so overshadowed by other planet announcements and barely received news coverage. It's pretty routine now, said Alan Boss, a planet formation theorist at the Carnegie Institution of Washington. Most planets that are found are not deemed worthy of a press release because they are sort of becoming 'one more planet.' The total is now more than 200 extrasolar planets confirmed. And this is the tip of the iceberg in planet finds. Astronomers have more tools than ever, and technology is so advanced that planet discovery has become almost mundane. The regularity of planet finds, luckily, is buffered by the wild variety in the discoveries themselves, including the following contrasts: nascent worlds of just a million years versus those that are billions of years old; hot gas giants and icy Neptune-like orbs; planets that whip around their parent stars with cosmic speed and others that seem to creep at a slug's pace; and planets orbiting double-stars, red-dwarf stars and even so-called failed stars. Transit technique Astronomers spotted TrES-3 as part of the Trans-atlantic Exoplanet Survey while looking for transiting planets, or those that pass directly in front of their home star with respect to Earth. It was detected with a network of telescopes in Arizona, California, and the Canary Islands. When TrES-3 coasted in front of its home star, the telescopes picked up a slight dimming of the star's light, by about 2.5 percent. The scientists used the dimming to estimate the planet's mass, size and other properties. It is located 800 light-years away in the constellation Hercules about 10 degrees west of Vega, one of the brightest stars in the summer skies of the northern hemisphere. It is also a very massive planet-about twice the mass of the solar system's biggest planet, Jupiter-and is one of the planets with the shortest known periods, said a co-discoverer of TrES-3 Georgi Mandushev of the Lowell Observatory in Arizona. The giant orb orbits so close to its parent star, about 50 times closer than Earth is to the Sun, the astronomers estimate its temperature soars to about 1,500 degrees Kelvin. Stellar wobbles While the transit method provides astronomers with the best indirect information about an exoplanet, so far only about 20 transiting planets have been spotted. That's why the most successful (based on the number of planet finds) teams have relied on the so-called wobble method, or radio-velocity technique. The radial-velocity teams are the most successful, Boss told SPACE.com. They are a victim of their own success. They are able to get more and more telescope time, because they can prove to the assignment committees that give out the time that 'if you give us so many more nights we can probably find you so many more planets,' Boss said. He added, The key bottleneck for finding more planets is simply more time on a telescope. The firsts and superlatives In addition to finding new worlds, the burgeoning field has achieved many firsts. In 2001, a team led by David Charbonneau of the Harvard-Smithsonian Center for Astrophysics used the Hubble Space Telescope and NASA's infrared-detecting Spitzer Space Telescope to detect for the first time the atmosphere of an extrasolar hot Jupiter called HD 189733b. Another hot Jupiter, Upsilon Andromeda b, revealed for the first time an exoplanet with a temperature variation across its surface: One side has temperatures rivaling those found deep in a volcano while the other face could plunge below freezing. Superlatives abound as well, with discoveries gaining fame as the windiest, tiniest, most massive and fastest orbiter. Shortest orbital period in catalog: HD 41004 B b completes a full orbit in 1.328 days. Longest orbit: HD 154345 b takes 13,100 days to orbit its parent star. Lightest planet: Gliese 581 C weighs just five Earth masses. Planet organizer In an effort to keep track of the rapidly increasing list of exoplanets, a group of astronomers published a catalog of nearby exoplanets within 652 light-years of Earth in a 2006 issue of the Astrophysical Journal, though they realize updates will be a must on a routine basis. Without question, the catalog presented here will become out of date before it is printed, the
Re: [meteorite-list] So many parent bodies, so few samples
Hi, Darren, List, exact solar system analogs and we wouldn't know it because we haven't been able to take data for long enough to actually find their planetary systems... I'd like to be wrong, but I think it's going to be a long wait. Let's say you're dozens of light years away from us and luckily, you're in the plane of the planets. You set up your automatic giant telescope system and wait for the Earth to cross in front of The Sun. The Earth is only 1/100th of the diameter of the Sun and so only blocks 1/1th of the Sun's light. So you're waiting for up to 365 days for the Sun to dim by 0.01%. Of course, there are sunspot clumps that dim the Sun that much but they take days to cross the Sun. So, you can distinguish between a big sunspot and a terrestrial planet no matter how far out it is. The Earth will only take less than thirteen hours to cross the Sun's disc when viewed from far away. But the problem of spotting the Earth is nothing when compared to catching Mercury! Mercury will only dim the Sun by about a 1/10th of the amount the Earth will, or 0.001% for less than eight hours. Good luck, alien planet hunters! Fortunately for you, there's bigger game to hunt. Yes, it's the Solar System's Big Boy -- Jupiter -- that catches all the attention. It will dim the Sun by almost 1% and the dimming transit will last 30 hours. Jupiter will be the Catch of the Day for an alien planet hunter. But it may not be the first to be discovered because our poor alien will have to wait for up to almost 12 years for Jupiter to show up in his 'scope... the first time. Just like our planet hunters, They will go through a few full cycles of the whole system, to be sure. That will kill most of a century. I hope we're worth it. Since the technique requires only big telescopes (in orbit would be nice), simple automated machinery, and LOTS of patience... Well, OK, you need to be near the plane defined by the planetary plane of the solar system -- that's about 3% of the stars within a given volume. How many is that? Well, there's about 14,000 stars with 100 light years (3% = 420). Hipparchos says 22,010 stars within 326 light years (3% = 660). There are 3919 Sun-like stars (spectral type F8 through K3) within 100 light years. These are stars very much like the Sun; if you were standing on Earth-like planet (and were not distracted by being on an alien planet), it would be indistinguishable from the Sun at first glance. Of those 3919 stars, about 120 of them are in a place where they can spot Our Solar System EASY -- it's like shooting planets in a barrel... or something like that. Out to 200 light years, that is A THOUSAND Sun-like stars (and their planets and their aliens) that can easily find us with such simple means as these. With a big orbital telescope farm and the steadfastness we all need, detection within 1,000 light years is no problem. There are 120,000 Sun-like stars in that volume well-placed to find and catalog our Solar System in detail. No doubt the systems that have suitable planets in what They think is the habitable zone are referred to Their Big Eye scope for some spectroscopy and visualization. Perhaps suitable candidates go on the list for a light-sail fly-by probe. Let's all be on our best behavior. Who knows? THEY may be watching. Or is it THEM? Sterling K. Webb -- - Original Message - From: Darren Garrison [EMAIL PROTECTED] To: meteorite-list@meteoritecentral.com Sent: Monday, June 11, 2007 2:52 PM Subject: [meteorite-list] So many parent bodies, so few samples http://www.space.com/scienceastronomy/070611_mm_planet_floodgates.html Trickle of Planet Discoveries Becomes a Flood By Jeanna Bryner Staff Writer posted: 11 June 2007 07:10 am ET Alien worlds, once hidden from knowledge, are now being discovered in droves, stunning astronomers with their unique features and sheer numbers. The discoveries are so common that more and more don't even get reported outside scientific circles. Take the announcement at the end of May of a massive planet, dubbed TrES-3, that zips around its star in an amazingly rapid 31 hours, giving the planet a 1.3-day year. Astronomers issued a press release, but you might not have heard about it because the discovery was so overshadowed by other planet announcements and barely received news coverage. It's pretty routine now, said Alan Boss, a planet formation theorist at the Carnegie Institution of Washington. Most planets that are found are not deemed worthy of a press release because they are sort of becoming 'one more planet.' The total is now more than 200 extrasolar planets confirmed. And this is the tip of the iceberg in planet finds. Astronomers have more tools than ever, and technology is so advanced that planet discovery has become almost mundane. The regularity of planet finds, luckily, is buffered by the wild variety
