* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download March 2017 - Shasta Astronomy Club
Dialogue Concerning the Two Chief World Systems wikipedia , lookup
Fermi paradox wikipedia , lookup
Advanced Composition Explorer wikipedia , lookup
Perseus (constellation) wikipedia , lookup
Outer space wikipedia , lookup
Circumstellar habitable zone wikipedia , lookup
Theoretical astronomy wikipedia , lookup
James Webb Space Telescope wikipedia , lookup
Cygnus (constellation) wikipedia , lookup
Astrophotography wikipedia , lookup
Nebular hypothesis wikipedia , lookup
IAU definition of planet wikipedia , lookup
Corvus (constellation) wikipedia , lookup
Future of an expanding universe wikipedia , lookup
High-velocity cloud wikipedia , lookup
Space Interferometry Mission wikipedia , lookup
Aquarius (constellation) wikipedia , lookup
Definition of planet wikipedia , lookup
Directed panspermia wikipedia , lookup
Rare Earth hypothesis wikipedia , lookup
Hubble Deep Field wikipedia , lookup
Astrobiology wikipedia , lookup
History of astronomy wikipedia , lookup
Solar System wikipedia , lookup
Stellar kinematics wikipedia , lookup
History of Solar System formation and evolution hypotheses wikipedia , lookup
Planetary system wikipedia , lookup
International Ultraviolet Explorer wikipedia , lookup
Formation and evolution of the Solar System wikipedia , lookup
Planetary habitability wikipedia , lookup
Star formation wikipedia , lookup
Extraterrestrial life wikipedia , lookup
Observational astronomy wikipedia , lookup
Shasta Astronomy Club Newsletter discovered five additional ones, increasing the number of known planets in the system to seven. The new results were published Wednesday in the journal Nature, and announced at a news briefing at NASA Headquarters in Washington. Using Spitzer data, the team precisely measured the sizes of the seven planets and developed first estimates of the masses of six of them, allowing their density to be estimated. NASA Telescope Reveals Largest Batch of EarthSize, Habitable-Zone Planets Around Single Star NASA’s Spitzer Space Telescope has revealed the first known system of seven Earth-size planets around a single star. Three of these planets are firmly located in the habitable zone, the area around the parent star where a rocky planet is most likely to have liquid water. The discovery sets a new record for greatest number of habitable-zone planets found around a single star outside our solar system. All of these seven planets could have liquid water – key to life as we know it – under the right atmospheric conditions, but the chances are highest with the three in the habitable zone. “This discovery could be a significant piece in the puzzle of finding habitable environments, places that are conducive to life,” said Thomas Zurbuchen, associate administrator of the agency’s Science Mission Directorate in Washington. “Answering the question ‘are we alone’ is a top science priority and finding so many planets like these for the first time in the habitable zone is a remarkable step forward toward that goal.” At about 40 light-years (235 trillion miles) from Earth, the system of planets is relatively close to us, in the constellation Aquarius. Because they are located outside of our solar system, these planets are scientifically known as exoplanets. This exoplanet system is called TRAPPIST-1, named for The Transiting Planets and Planetesimals Small Telescope (TRAPPIST) in Chile. In May 2016, researchers using TRAPPIST announced they had discovered three planets in the system. Assisted by several ground-based telescopes, including the European Southern Observatory’s Very Large Telescope, Spitzer confirmed the existence of two of these planets and Based on their densities, all of the TRAPPIST-1 planets are likely to be rocky. Further observations will not only help determine whether they are rich in water, but also possibly reveal whether any could have liquid water on their surfaces. The mass of the seventh and farthest exoplanet has not yet been estimated – scientists believe it could be an icy, “snowball-like” world, but further observations are needed. “The seven wonders of TRAPPIST-1 are the first Earth-size planets that have been found orbiting this kind of star,” said Michael Gillon, lead author of the paper and the principal investigator of the TRAPPIST exoplanet survey at the University of Liege, Belgium. “It is also the best target yet for studying the atmospheres of potentially habitable, Earth-size worlds.” In contrast to our sun, the TRAPPIST-1 star – classified as an ultra-cool dwarf – is so cool that liquid water could survive on planets orbiting very close to it, closer than is possible on planets in our solar system. All seven of the TRAPPIST-1 planetary orbits are closer to their host star than Mercury is to our sun. The planets also are very close to each other. If a person was standing on one of the planet’s surface, they could gaze up and potentially see geological features or clouds of neighboring worlds, which would sometimes appear larger than the moon in Earth’s sky. The planets may also be tidally locked to their star, which means the same side of the planet is always facing the star, Star Star Party Party Location: Location: OakOak Bottom Bottom Marina Marina Parking Parking Lot.Lot March March 2017 2017 Shasta Astronomy Club Newsletter therefore each side is either perpetual day or night. This could mean they have weather patterns totally unlike those on Earth, such as strong winds blowing from the day side to the night side, and extreme temperature changes. Spitzer, an infrared telescope that trails Earth as it orbits the sun, was well-suited for studying TRAPPIST-1 because the star glows brightest in infrared light, whose wavelengths are longer than the eye can see. In the fall of 2016, Spitzer observed TRAPPIST-1 nearly continuously for 500 hours. Spitzer is uniquely positioned in its orbit to observe enough crossing – transits – of the planets in front of the host star to reveal the complex architecture of the system. Engineers optimized Spitzer’s ability to observe transiting planets during Spitzer’s “warm mission,” which began after the spacecraft’s coolant ran out as planned after the first five years of operations. “This is the most exciting result I have seen in the 14 years of Spitzer operations,” said Sean Carey, manager of NASA’s Spitzer Science Center at Caltech/IPAC in Pasadena, California. “Spitzer will follow up in the fall to further refine our understanding of these planets so that the James Webb Space Telescope can follow up. More observations of the system are sure to reveal more secrets.” Following up on the Spitzer discovery, NASA’s Hubble Space Telescope has initiated the screening of four of the planets, including the three inside the habitable zone. These observations aim at assessing the presence of puffy, hydrogen-dominated atmospheres, typical for gaseous worlds like Neptune, around these planets. Mapping the family tree of stars Astronomers are borrowing principles applied in biology and archaeology to build a family tree of the stars in the galaxy. By studying chemical signatures found in the stars, they are piecing together these evolutionary trees looking at how the stars formed and how they are connected to each other. The signatures act as a proxy for DNA sequences. It’s akin to chemical tagging of stars and forms the basis of a discipline astronomers refer to as galactic archaeology. It was Charles Darwin, who, in 1859 published his revolutionary theory that all life forms are descended from one common ancestor. This theory has informed evolutionary biology ever since but it was a chance encounter between an astronomer and a biologist over dinner at King’s College in Cambridge that got the astronomer thinking about how it could be applied to stars in the Milky Way. Writing in Monthly Notices of the Royal Astronomical Society, Dr. Paula Jofré, of the University of Cambridge’s Institute of Astronomy, describes how she set about creating a phylogenetic “tree of life” that connects a number of stars in the galaxy. Star Party Location: Oak Bottom Marina Parking Lot March 2017 Shasta Astronomy Club Newsletter “The use of algorithms to identify families of stars is a science that is constantly under development. Phylogenetic trees add an extra dimension to our endeavours which is why this approach is so special. The branches of the tree serve to inform us about the stars’ shared history,” she says. The team picked 22 stars, including the Sun, to study. The chemical elements have been carefully measured from data coming from ground-based high-resolution spectra taken with large telescopes located in the north of Chile. Once the families were identified using the chemical DNA, their evolution was studied with the help of their ages and kinematical properties obtained from the space mission Hipparcos, the precursor of Gaia, the spacecraft orbiting Earth that was launched by the European Space Agency and is almost halfway through a 5-year project to map the sky. Stars are born from violent explosions in the gas clouds of the galaxy. Two stars with the same chemical compositions are likely to have been born in the same molecular cloud. Some will live longer than the current age of the universe and serve as fossil records of the composition of the gas at the time they were formed. The oldest star in the sample analysed by the team is estimated to be almost ten billion years old, which is twice as old as the Sun. The youngest is 700 million years old. In evolution, organisms are linked together by a pattern of descent with modification as they evolve. Stars are very different from living organisms, but they still have a history of shared descent as they are formed from gas clouds, and carry that history in their chemical structure. By applying the same phylogenetic methods that biologists use to trace descent in plants and animals it is possible to explore the ‘evolution’ of stars in the galaxy. “The differences between stars and animals is immense, but they share the property of changing over time, and so both can be analysed by building trees of their history,” says Professor Robert Foley, of the Leverhulme Centre for Human Evolutionary Studies at Cambridge. With an increasing number of datasets being made available from both Gaia and more advanced telescopes on the ground, and on-going and future large spectroscopic surveys, astronomers are moving closer to being able to assemble one tree that would connect all the stars in the Milky Way. Astronomers discover a new satellite for the Milky Way Phil Plait Galaxies are immense structures. Composed of gas, dust, dark matter, and billions of stars, big ones can be a hundred thousand light-years across — a million trillion kilometers — and have masses equaling trillions of Suns. Our own Milky Way fits those numbers pretty well. It formed not long after the Universe, itself, did, probably a billion or so years after the Big Bang, collapsing from a vast cloud of hydrogen and helium gas. It wasn’t alone, though: Two other big galaxies were born along with it (the Andromeda Galaxy and Triangulum), and a handful of smaller ones that are all bound by their mutual gravity, forming what we call the Local Group. Some of these galaxies are actually satellites of the Milky Way, in a similar way that the Moon is a satellite of Earth. The two biggest are the Large and Small Magellanic Clouds, with about 10 billion and a few hundred million stars in them respectively, but we know of a few dozen very small dwarf galaxies also in orbit around us. Most of them are extremely faint and hard to detect, and we’re not really sure how many there are in total. That’s actually important to know. Different theories and models of how galaxies form predict different numbers and distributions of dwarf satellite galaxies. To differentiate them, astronomers scan the skies looking for more Milky Way companions. These surveys are paying off: Nine dwarf candidate (meaning as yet unconfirmed) satellites were found in 2015. Late last year, in 2016, another was discovered, and it’s pretty cool. It was found using the Hyper Suprime-Cam instrument on the gigantic Subaru 8.2 meter telescope. The HSC is itself a bit of a monster; it’s over two meters long, weighs three tons, and takes enormous 870 megapixel images that cover 1.5° of the sky on a side. The Moon is about 0.5°, so this covers an area nearly ten times the area of the Moon. Astronomers aimed it at five separate regions of the sky, covering a total of 100 square degrees (that’s a lot). They mapped Star Party Location: Oak Bottom Marina Parking Lot. March 2017 Shasta Astronomy Club Newsletter where all the objects were in the fields, separated stars from distant background galaxies (stars are point sources, whereas most galaxies are slightly extended), and then looked for places where there were more stars than expected — hoping some might be faint Milky Way satellites. In the constellation of Virgo, they found such a clump. It’s unlikely to be a random fluctuation in the distribution of Milky Way stars masquerading as a physical clump; it’s better than 99% certain to be an actual object. To make sure, the astronomers did something clever. In an old dwarf satellite galaxy, it’s reasonable to assume all the stars in it were born at the same time; these galaxies tend to form stars right as the galaxy, itself, forms, then run out of gas to make any more. If the stars instead belong to our Milky Way they would have all different ages, since we’re still actively churning them out. Using models of how stars change color as they age, the astronomers were able to show that the stars in the clump do look to be about the same age —about 13 billion years. Not only that, if they throw away the stars that don’t match that age, the statistical significance of the clump being real jumps up to near certainty. So, this appears to be a real galaxy, which they’ve dubbed Virgo I. The distance (measured by looking at the brightness of the stars in it) is about 280,000 light years away; three times the width of the Milky Way, itself. The size is a bit difficult to determine; galaxies aren’t solid objects and fade with distance from their centers. But it appears this object is roughly 300 light years across. That, in itself, is interesting. First, that’s tiny. Second, there are objects called globular clusters, which are magnificent collections of hundreds of thousands of stars in a ball, all orbiting their common center of mass like bees buzzing around a hive. About 150 of them are known to orbit the Milky Way. While the numbers of stars in a typical globular cluster is similar to Virgo I, the latter is much bigger than what you’d expect for a globular at that distance, making it even more likely this is, indeed, a galaxy. So, this looks to be a legit dwarf galaxy, likely a satellite of the Milky Way, so small and faint it’s escaped detection until now. Now, here’s a fun fact: The astronomers looked at 100 square degrees of sky and found one such object. But there are over 40,000 square degrees of sky, so extrapolating from that means there may be hundreds of these dinky galaxies yet to find! Happily, the survey that found Virgo I is ongoing, so hopefully they’ll start finding more. It’s rather amazing to me that we can see galaxies billions of light years way, nearly to the edge of the observable Universe, but there can be galaxies literally orbiting our own that have gone unnoticed. Of course, the ones we see at fantastic distances are huge and bright, and the nearby ones small and faint. But still, it shows you that, sometimes, treasures can be found on your doorstep if you just look more carefully. A map of the number of stars seen in the region of Virgo I (left) shows a clump at its location, whereas extended galaxies (right) does not. Credit: Homma et al. virgoi_map.jpg Star Party Location: Oak Bottom Marina Parking Lot March 2017 Shasta Astronomy Club Newsletter teaming up with private spaceflight companies, a model that is expected to be utilized in the administration in general. Along with the Webb telescope, NASA has two telescopes based on modified versions of the Hubble design donated by the National Reconnaissance Office. One such mission, the Wide Field Infrared Survey Telescope, will be utilized as an exoplanet and dark matter hunter to be launched in the mid-2020s. Plans for the other telescope have not yet been announced. Meteorites Date Demise of Solar Nebula Another Hubble repair mission could be on the way By: David Dickinson Preliminary reports suggest the Trump administration may team up with Sierra Nevada to bring new life to an old telescope. A study of ancient meteorites has refined the date for the dissolution of the solar nebula, the cloud of dust and gas that shrouded our Sun in its earliest days. By John Wenz The Hubble Space Telescope, launched in 1990, has provided a wellspring of information about our universe over the last 27 years. Some of those discoveries required five upgrades to the system. And now, according to a Wall Street Journal report, there could be a sixth. According to the report, the servicing would provide an “insurance policy” in case the James Webb Space Telescope, which will perch itself far from low-Earth orbit (and even beyond the Moon) at a stable point called L2. With the space shuttle program ending in 2011, there isn’t a vehicle to complete the mission. Yet. But Sierra Nevada, a private spaceflight company, has worked for years on a miniature space shuttle called the Dream Chaser, based on older designs generated in the early days of NASA. Right now, the craft is only cleared for automated flights and may resupply the ISS as soon as 2019. The project would require a human-piloted variant relying on infrastructure that already exists in the ship’s design. According to the WSJ report, the possibility is currently in the (very) preliminary stages. It would represent a public-private venture that would drive down federal government costs by What would we see in our solar system if we could go back billions of years? Much of what transpired during the solar system’s formation is lost to time. But as we explore worlds outside our own system, it would be valuable to know just how common — or rare — the our solar system is in the grand drama of the Universe. Now, a recent study by a Massachusetts Institute of Technology (MIT) team has pinpointed a key period during our solar system’s formation when the Sun had blown away the cloud of dust and gas enshrouding it. Our solar system formed about 4.6 billion years ago, when a giant, magnetized cloud of dust and molecular hydrogen gas collapsed to form the Sun and, not long thereafter, its attendant planets. However, once the Sun ignited fusion within its core, it began to shine and the pressure from its radiation and solar wind started slowly lifting the curtain of dust and gas pervading the inner solar system. The solar nebula that had fed the infant star soon dispersed. We have witnessed other “proto-solar systems,” such as the proplyds dotting the Orion Nebula, in the act of formation today. Going off of such snapshots of infant systems, astronomers gauged the lifetime of the early solar nebula at 1 to 10 million years. The recent MIT study, published in the February 9th Star Party Location: Oak Bottom Marina Parking Lot. March 2017 Shasta Astronomy Club Newsletter The Wild Times of the Solar System’s Youth The early years of the solar system were wild and chaotic, with the solar nebula’s gravitational forces driving planets’ migrations about the system. “When the solar nebula is present, it exerts a gravitational force on the giant planets.” says Weiss. “This [force] can cause the planets’ orbits to change rapidly, typically evolving inward toward the Sun.” This may also explain the proliferation of “hotJupiters,” or exoplanets seen in tight orbits around their host stars that have since migrated inward. The nebula’s dissipation after 3.8 million years would have ended most of this disorder, giving rise to an arrangement of planets familiar to us today. Proplyds (insets) dot the stellar nursery of the Orion Nebula (M42), located 1,350 light-years away. NASA / ESA / M. Robberto (Space Telescope Science Institute/ESA) / Hubble Space Telescope Orion Treasury Project Team and L. Ricci (ESO) heic0917ab.jpg Science, refines these estimates, putting the end of the solar nebula at 3 to 4 million years. “Our solar nebula’s lifetime appears to be right in the middle of what is observed for Sun-like stars,” says Benjamin Weiss (MIT). The team arrived at their estimate by looking at some of the oldest meteorites on Earth, known as angrites, including meteorites collected from Antarctica, the Sahara, Brazil, and Argentina. The Argentine D’Orbiny meteorite in particular has a storied history, as the rock was found while a farmer was tilling his field and resided by his farmhouse for 20 years before it was analyzed and identified as a rare angrite meteorite — the largest specimen discovered. These rocks contain a high amount of uranium, whose steady decay enables researchers to pinpoint the rocks’ formation at 4.653 billion years ago. Also, the rocks’ magnetism was frozenin during their formation, giving researchers a record of what the magnetic field was like at the time. The team tested the angrites using a precision magnetometer at the MIT Paleomagnetism Laboratory and found remnant magnetism so weak, it could have only been produced in an extremely weak magnetic field of no more than 0.6 microteslas about 3.8 million years after the solar system’s formation. By contrast, back in 2014 the same team had looked at even older meteorites, which had formed 2 to 3 million years after the solar system, and found evidence for a magnetic field of 5 to 50 microteslas pervading the early solar system. The more than tenfold drop in the strength of the solar nebula’s magnetic field indicates that the nebula itself had all but dissipated by 3.8 million years after the solar system’s birth. This result also throws another piece of evidence into the planet formation ring, where two scenarios vie to explain the formation of Jupiter and Saturn. In the two-stage scenario known as core accretion, bits of rock fused together to form these gas giants’ cores, which then attracted huge shrouds of gas. The opposing scenario, called gravitational collapse, proposes that the gas giants formed all at once, much as the Sun did. The two scenarios happen on vastly different timescales: gravitational collapse would have occurred over about 100,000 years, while core accretion would have taken millions of years. The persistence of the solar nebula over 3 to 4 million years means the core accretion hypothesis remains viable, but it also constrains the length of time that mechanism would have been allowed to operate. The refined age of the solar nebula puts one more piece into place in the puzzle of our solar system’s formation. Looking out at other exoplanetary systems at various stages will give us further insight into how the process unfolds. Missions like the Transiting Exoplanet Survey Satellite (TESS) and the James Webb Space Telescope (JWST), for example, are set to up the tally of known worlds, which currently stands at 3,576. Also, sample return missions such as JAXA’s Hayabusa 2 and Osiris-REX may confirm or refute the findings gathered from meteorites found here on Earth. Finally, NASA’s Juno spacecraft is currently probing the interior of Jupiter, and we may soon know if it has a rocky core at its very heart, or if it’s pure metallic hydrogen all the way through. Get ready for a renaissance in planetary science, as the mystery of the solar system’s formation continues to unfold. Star Party Location: Oak Bottom Marina Parking Lot March 2017 Shasta Astronomy Club Newsletter March 2017 Sunday Monday Tuesday Wednesday Thursday Friday Saturday 1 2 3 4 7 8 9 10 11 12 13 Daylight Savings Time Begins 14 15 16 17 18 19 21 22 23 24 25 5 6 20 Star Party 7pm Oak Bottom Marina Parking Lot Club Breakfast 8am Humble Joes Star Party 7pm Oak Bottom Marina Parking Lot 26 27 28 29 30 31 Star Party Location: Oak Bottom Marina Parking Lot. March 2017