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Exciting news from the heavens! Today NASA has reported that the Kepler mission has discovered 3 new planets in the habitable zones of two distant stars. Of the thousands of worlds so far discovered, these three are most likely to be habitable. Best of all the planets are crazy!
Kepler is a NASA space telescope which was launched on March, 2009. It makes use of an incredibly sensitive photometer to simultaneously & incessantly monitor the brightness of over 150,000 nearby stars. The brightness of a star dims slightly whenever an exoplanet transits between it and Kepler. Thanks to Kepler’s inhuman vigilance and robotic ability to perceive nearly imperceptible light changes, we are now discovering thousands of new planets, although most of them are Jovian sized gas worlds.
The three worlds reported today lie in the habitable zone—the region around a star where water exists in a liquid form (as it does here on beautiful Earth). Two of the newly discovered habitable zone planets are in a five planet system orbiting a dwarf star just two-thirds the size of the sun which lies 1,200 light years from Earth. Here is a diagram of the Kepler 62 system.
Of these five worlds, two lie in the habitable zone, Kepler 62f and Kepler 62e. Kepler 62 F is most likely a rocky planet and is only 40 percent larger than Earth. It has an orbit which last 267 (Earth) days. So far it is the smallest exoplanet found in the habitable zone. The star it orbits is 7 billion years old (as opposed to the sun which is four and a half billion years old) so life would have had plenty of time to develop. The other habitable zone planet in the Kepler 62 system, Kepler 62e is probably about 60% larger than our planet. It is somewhat closer to the star and astrophysicists speculate it may be a water world of deep oceans.
The other new exoplanet Kepler-69c appears to orbit a star very similar to Earth’s sun. It orbits at the inward edge of the habitable zone (nearing where Venus is in our solar system) so it may be hot. The planet is estimated to be about 70% larger than Earth, and is also thought to be a water world with oceans thousands of kilometers deep. I am finding it impossible not to imagine those vast oceans filled with asbestos shelled sea-turtles the size of dump trucks, huge shoals of thermophile micro-squid, and burning-hot chartreuse uber-penguins, but if any life is actually on Kepler-69c, it is probably extremely different from Earth life.
Of course Kepler can only find these planets; it is unable to observe very much about them. In order to do that, humankind will need some sort of huge amazing super telescope. Speaking of which, tune in next week when I write about humankind’s plans for building a huge amazing super telescope in the Chilean Andes!
My apologies for the blogging break last week. Usually I try to write a new post every weekday, but last week was a blogging holiday. To reinvigorate things after the lost week, let’s turn to a big subject—in fact a super-massive subject! Long ago, Ferrebeekeeper featured a post about Eta Carinae, a blue hypergiant with a hundred times the mass of the sun (which is itself a million times more massive than Earth). Stars like Eta Carinae are rarely formed and short lived—there are probably less than a dozen in our galaxy. However compared to the most massive object in the galaxy, Eta Carinae is puny and common. Twenty six thousand light years away from the solar system there exists a truly monstrous space object!
In 1974, Astronomers discovered an astronomical feature which was emitting exotic radio waves in the Sagittarius constellation. The scientists named the feature “Sagittarius A” and set out to determine what it was. Part of the feature seems to be the remnants of a star which had gone supernova. A second part of the feature is a cloud of ionized gas surrounded by an even larger torus of molecular gas. In the middle of Sagittarius A is something which is emitting most of the high energy electromagnetic radiation visible to radio telescopes. The cloud of ionized gas seems to be emptying into it and nearby stars orbit it with greater velocity than stars move anywhere else in the galaxy (in fact the object affects the proper motion of thousands of nearby stars). And yet the space object at the center of Sagittarius A has a diameter of only 44 million kilometers–a bit less than the distance between the middle of the sun and Mercury at its perihelion (when the rocky planet is closest to the sun). By calculating the proper motion of thousands of nearby stars, scientists determined that the mysterious object at the center of Sagittarius A (which they took to calling Sagitarrius A*) has mass of 4.31 million suns (i.e. solar masses). Whatever lies at the center of Sagittarius A–which I probably should have mentioned, is also the center of the Milky Way Galaxy–is smaller in volume than a large star, but has a mass which exceeds by many orders of magnitude even exotic hypergiants like Eta Carina.
Of course the only kinds of discrete objects which we know (or even hypothesize) to be capable of attaining such mass are black holes. It is believed that most (indeed probably all) galaxies have super-massive black hole at their centers. Smaller galaxies have small super massive black holes (forgive the oxymoron) but large galaxies have immense central black holes which can equal billions of solar masses. Radio astronomers have observed plumes of exotic electromagnetic radiation coming from the center of other galaxies, and they wondered where the Milky Way’s galactic center was located. It seems that a supernova near the galactic center blew away a great deal of the dust and gas on which the black hole would otherwise “feed” thereby making the galactic center of the Milky Way less energetic than the active center of farther (e.g. older) galaxies.
The super massive black holes which lie at the center of galaxies may be a result of the accretion of matter around stellar-sized black holes (which could grow quickly in matter-rich galactic cores) but most astrophysicists believe they are instead a primordial feature of the Big Bang around which galaxies themselves coalesced. The ultimate nature of super massive black holes remains unknown and seems to be tied to the nature and shape of our universe.