2019-12-14 12:08:17|三中三怎么买才算中


  NASA’s new planet-hunting machine, the Transiting Exoplanet Survey Satellite, or TESS, is racking up scores of alien worlds.

  Less than a quarter of the way through a two-year search for nearby Earthlike worlds, TESS has already discovered 203 possible planets, according to George R. Ricker, an astrophysicist at the Massachusetts Institute of Technology, and the leader of the project. Three of those candidates already have been confirmed as real planets by ground-based telescopes.

  On Monday afternoon, Dr. Ricker and his colleagues issued a progress report on humankind’s latest search for friends or at least neighbors. The mission, they said at a meeting of the American Astronomical Association in Seattle, was well on track to its official goal of finding and measuring the masses of at least 50 planets that are no larger than four times the size of Earth.

  “The torrent of data has already begun,” Dr. Ricker said.

  All of these worlds would be located within 300 light years from here, our cosmic backyard, and close enough to be inspected by future telescopes, such as NASA’s ever-upcoming James Webb Space Telescope, for signs of atmospheres, habitability and, perhaps, life. These worlds are the next frontier beyond our own solar system for answering the haunting question of whether life, in whatever form it might be recognized, has arisen elsewhere in the universe.

  The most recently confirmed of these planets received star billing in Seattle. In the words of its discoverer, Diana Dragomir of M.I.T., the planet is a “weird” ball or rock and some gas about three times the size of Earth. Every 36 days it orbits a dwarf star called HD 21749, about 53 light-years away in the constellation Reticulum.

  According to calculations by Dr. Dragomir, the planet is close enough to its star that its surface temperature is about 300 degrees Fahrenheit. That gives it one of the coolest surface temperatures found around such a star, but a bit toasty for life as we know it.

  The planet’s nature is a puzzle. Its size puts it in a category called sub-Neptune, of which no examples exist in our own solar system. But it is much denser than Neptune (though not as dense as the Earth), Dr. Dragomir explained, suggesting that the new planet was mostly rock with a relatively small dense atmosphere.

  Intriguingly, the team also detected hints of what might be a second planet circling the same star in a much closer orbit. It appears to be even smaller than the Earth, which would make it the smallest planet Tess has yet found. “We haven’t measured the mass of a planet the same size Earth yet,” Dr. Dragomir said.

  If this second observation holds up, the Reticulum system would become an attractive target for astronomers studying the architecture of exoplanet systems.

  “The future of exoplanet science is bright,” Dr. Dragomir and her colleagues wrote in a paper submitted to the Astrophysical Journal that described the new results.

  That is an understatement of astronomical proportions. In the last three decades, and aided by NASA’s planet-hunting Kepler spacecraft, astronomers have concluded that there are billions of planets, including potentially habitable rocky worlds like Earth, in the Milky Way galaxy. The closest one, astronomers calculate, could be just 10 or 15 light years from here.

  TESS was designed and built to reveal such planets, by monitoring the light from stars for any periodic dimming or blinking, which would indicate that planets are passing in front of them.

  For the purposes of the survey, the sky has been divided into 26 segments that resemble orange slices. The spacecraft’s four small cameras stare at each segment in turn for 27 days. In the first year, the researchers will survey the entire southern hemisphere of the sky; in the second year, they will stitch together the northern sky.

  TESS will measure the brightnesses of nearly 200,000 stars every two minutes, and record an image of the entire swath of sky in the segment every half-hour. That cadence is perfect for finding and studying the exoplanets most likely to be habitable, said Sara Seager, an M.I.T. planet expert and a member of the TESS team.

  Most of the stars on TESS’s watch are so-called red dwarfs, smaller and dimmer than the sun, Dr. Seager said. Planets in the habitable zones of such stars orbit them in a matter of days or weeks, not the 365 days of our own year.

  Dr. Dragomir and her team went to great effort to infer the existence of the new Reticulum planet. The team initially detected only one telltale dip in the light from HD 21749, the red dwarf in Reticulum. That was not enough information: Three dips are the standard for establishing the potential signal of an exoplanet. But a signal that repeated every 36 days would not reappear in a 27-day observing window. And the star is erratic, prone to outbursts that can mimic a planet transit.

  Dr. Dragomir opted for a second opinion, and looked at data collected from the High Accuracy Radial-velocity Planet Searcher, or Harps, an instrument in Chile that detects and weighs exoplanets by the jiggles they impart to their home stars as they orbit.

  The Harps team had observed the star HD 21749, but had never concluded whether or not a planet was there, too. Dr. Dragomir found a signal in the Harps data with a 36-day period, and calculated that if the dip that TESS saw was real, it should reappear 36 days later in data from an adjacent sector of the sky. (The sectors overlapped slightly.)

  Dr. Dragomir was chagrined to then discover a glitch in that part of the data. Swallowing disappointment, the team re-examined the data more carefully and found what looked like the last part of a transit signal after all. Mathematically, it was a perfect match to the first transit they had seen.

  Add another oddball planet, if not a future home for humans, to the record of nature’s inventiveness.

  “There was quite some detective work involved, and the right people were there at the right time,” Dr. Dragomir said. “But we were lucky, and we caught the signals, and they were really clear.”



  三中三怎么买才算中“【就】【是】,【苏】【老】【弟】【你】【多】【虑】【了】,【自】【从】【我】【来】【到】【这】【山】【上】【后】,【就】【根】【本】【没】【见】【过】【其】【他】【人】【来】【这】【里】!【怕】【是】【还】【以】【为】【这】【里】【完】【全】【是】【荒】【郊】【野】【岭】【呢】!【谁】【没】【事】【会】【来】【这】【里】【啊】!”【小】【三】【听】【后】【倒】【是】【很】【不】【在】【乎】,【无】【所】【谓】【的】【说】【道】。 【苏】【白】【却】【是】【心】【中】【一】【动】,【小】【三】【来】【到】【这】【里】【之】【后】,【竟】【然】【没】【有】【见】【过】【其】【他】【人】?【这】【怎】【么】【可】【能】【呢】!【现】【在】【的】【龙】【虎】【山】,【虽】【然】【不】【是】【什】【么】【旅】【游】【胜】【地】,【可】【是】【景】


【不】【管】【外】【界】【如】【何】【变】【化】,【此】【时】【身】【在】【第】【十】【界】【域】【之】【中】【的】【夜】【羽】【等】【人】【已】【经】【是】【完】【全】【的】【陷】【入】【了】【对】【于】【未】【知】【世】【界】【的】【探】【索】【之】【中】。 【夜】【羽】【安】【静】【的】【走】【在】【一】【片】【密】【林】【之】【中】,【双】【眸】【警】【惕】【的】【看】【着】【四】【周】。 【这】【里】【就】【是】【第】【十】【界】【域】【吗】? 【似】【乎】【和】【外】【面】【的】【九】【大】【星】【域】【也】【并】【没】【有】【什】【么】【不】【同】? 【嗯】? 【等】【等】! 【我】【的】【修】【为】【在】【倒】【退】! 【感】【受】【着】【身】【体】【之】【中】【一】【点】【点】【消】【失】

  .. “【本】【事】【不】【大】,【脾】【气】【渐】【涨】。” 【青】【衫】【男】【子】【手】【中】【剑】【刃】【一】【撇】,【剑】【刃】【与】【戟】【身】【滑】【出】【一】【道】【长】【长】【的】【火】【花】,【顺】【着】【李】【轩】【击】【来】【的】【黑】【戟】【戟】【身】【滑】【至】【李】【悬】【手】【腕】【处】,【剑】【柄】【狠】【狠】【敲】【在】【李】【悬】【的】【手】【上】。 【李】【悬】【吃】【痛】,【手】【心】【倏】【放】【又】【紧】【紧】【抓】【住】【这】【长】【戟】,【比】【起】【身】【体】【的】【疼】【痛】,【李】【悬】【心】【中】【的】【震】【撼】【来】【的】【更】【为】【强】【烈】【些】。 【不】【可】【能】【是】【他】。 【李】【悬】【望】【着】【看】【起】三中三怎么买才算中【阿】【漠】【是】【被】【萋】【萋】【在】【西】【城】【捡】【到】【的】。 【当】【时】【的】【他】【像】【极】【了】【当】【年】【未】【曾】【遇】【到】【陆】【未】【郗】【的】【江】【萋】【萋】。 【西】【城】【旁】【边】【有】【一】【片】【沙】【漠】,【阿】【漠】【当】【时】【就】【在】【那】【里】。 【一】【个】【人】,【孤】【零】【零】【的】。 【他】【是】【个】【孤】【儿】,【记】【事】【起】【就】【一】【直】【在】【漂】【泊】。 【他】【没】【有】【名】【字】。 【萋】【萋】【见】【到】【他】,【问】【他】【叫】【什】【么】。 【他】【轻】【轻】【摇】【头】,【面】【上】【没】【有】【一】【丝】【表】【情】。 【萋】【萋】【说】,【我】【叫】【江】【萋】【萋】,

  【罪】【恶】【在】【进】【入】【地】【府】【的】【势】【力】【范】【围】【后】【并】【没】【有】【去】【研】【究】【各】【个】【地】【图】【势】【力】【分】【布】,【因】【为】【罪】【恶】【根】【本】【不】【关】【心】,【所】【以】【他】【并】【不】【知】【道】【他】【是】【从】【哪】【个】【森】【林】【出】【来】【的】,【边】【上】【的】【这】【条】【河】【是】【什】【么】【河】,【灭】【的】【城】【叫】【什】【么】【城】,【所】【以】【罪】【恶】【看】【着】【眼】【前】【奇】【怪】【的】【山】,【也】【不】【知】【道】【这】【是】【什】【么】【山】,【只】【不】【过】【因】【为】【这】【山】【上】【城】【堡】【中】【有】【他】【一】【魂】【的】【气】【息】,【所】【以】【才】【感】【兴】【趣】。 【刚】【来】【到】【山】【脚】【下】,【就】【看】【见】【一】

  【这】【个】【天】【地】【的】【昆】【仑】【宗】,【当】【初】【也】【是】【有】【着】【一】【口】【井】【的】,【当】【初】【的】【那】【口】【井】【的】【作】【用】【也】【和】【现】【在】【这】【口】【井】【差】【不】【多】,【也】【是】【连】【通】【一】【处】【空】【间】。 【只】【是】【当】【初】【的】【那】【口】【井】【连】【通】【的】【空】【间】【是】【魔】【界】【空】【间】,【里】【边】【是】【充】【斥】【魔】【气】【且】【有】【着】【无】【数】【魔】【族】【和】【魔】【物】【的】【空】【间】。 【而】【当】【初】【的】【昆】【仑】【宗】,【整】【个】【门】【派】【上】【上】【下】【下】【的】【任】【务】【就】【是】【镇】【守】【那】【口】【井】,【防】【止】【当】【中】【的】【魔】【族】【和】【魔】【物】【的】【跑】【出】【来】【危】【害】【人】

  【话】【说】【李】【濯】【尘】【突】【然】【回】【到】【了】【纳】【兰】【阴】【司】【身】【边】,【看】【着】【纳】【兰】【阴】【司】【说】【道】:“【已】【经】【处】【理】【的】【差】【不】【多】【了】,【他】【们】【体】【内】【的】【蛊】【毒】【也】【在】【扩】【散】,【就】【等】【您】【号】【令】【了】。” “【好】!【你】【看】【着】【这】【个】【死】【女】【人】,【让】【她】【亲】【眼】【看】【着】【这】【些】【人】【是】【如】【何】【痛】【苦】【的】【死】【去】。” “【是】!” 【只】【见】【纳】【兰】【阴】【司】【手】【指】【转】【动】,【嘴】【里】【念】【着】【一】【些】【陌】【凌】【涵】【根】【本】【听】【不】【懂】【的】【咒】【语】,【而】【拼】【命】【厮】【杀】【的】【人】,【不】【管】