藝術家設計的概念圖表明，在最近的已知行星系統(tǒng)中，其恒星“E波江”為兩個小行星帶環(huán)繞（內(nèi)側的小行星帶呈現(xiàn)為黃色，外側的小行星帶在前景中可以看到）。此外，該系統(tǒng)中還有一個外部環(huán)帶（見右上——角來自外部環(huán)帶的彗星），而且還有可能存在行星。
該圖表比較了“E波江”系統(tǒng)與太陽系：兩個系統(tǒng)的結構類似，都有小行星帶（棕色），彗星帶（藍色）和行星（白點）。
Nearby Star Hosts Three-Ring Circus
| A nearby star, visible with the unaided eye, is ringed with two rocky asteroid belts and an outer icy halo, making it a three-ring cosmic circus. The inner asteroid belt appears to be a virtual twin to the belt in our solar system. | 一顆肉眼可見的附近恒星，被兩個巖石小行星帶和一個多冰的外圍暈輪所環(huán)繞，使其成為由三個環(huán)帶圍繞的宇宙圓形系統(tǒng)。事實上，內(nèi)部的那個小行星帶跟我們太陽系的小行星帶猶如雙胞胎一般，極為相似。 |
| The presence of the separate rings of material around the nearby star, called Epsilon Eridani, suggests unseen planets lurk there, where they confine and shape the rings, say the researchers. | 研究人員說，附近的這顆恒星叫做“E波江（Epsilon Eridani）”，其周圍出現(xiàn)了分離的物質帶，說明有未觀察到的行星潛伏在那里，它們控制著環(huán)帶，并決定著環(huán)帶的形狀。 |
| If there were in fact rocky planets within the inner gap between the star and asteroid belt, the worlds would likely reside within the star's habitable zone where temperatures would be such that life could survive. | 如果在恒星和小行星帶之間的內(nèi)圍間隙中確實存在巖石行星，那么這些星球可能會位于這顆恒星的可居住帶上，其溫度可能會適于生命生存。 |
| Located 10.5 light-years from Earth in the constellation Eridanus, the star is the ninth closest to the sun. The sun's three nearest known stars are gravitationally bound in a system called Alpha Centauri that's located 4.36 light-years away. | 該恒星位于波江座，距地球10.5光年，在跟太陽距離最近的恒星中占第九位。已知跟太陽最近的三顆恒星叫做南門二，被引力束縛在同一個系統(tǒng)中，位于4.36光年以外。 |
| Epsilon Eridani is slightly smaller and cooler than the sun. And it's also younger. While the sun is an estimated 4.5 billion years old, Epsilon Eridani has been around for just 850 million years. | 恒星“E波江”比太陽稍微小一點，溫度比太陽稍微低一點。但是它比太陽更年輕。據(jù)估計，太陽有45億歲了，而“E波江”僅僅存在了8億5千萬年。 |
| "Studying Epsilon Eridani is like having a time machine to look at our solar system when it was young," said researcher Massimo Marengo, an astronomer at the Harvard-Smithsonian Center for Astrophysics in Massachusetts. | “研究恒星‘E波江’就象有了一臺時間機器，可以用來觀察我們太陽系年輕時的情形，”研究人員馬西莫·馬倫果說。馬倫果是馬薩諸塞州哈佛-史密森天體物理中心的一位天文學家。 |
| Rocky rings | 巖石環(huán)帶 |
| Astronomers had known about the star's outer icy ring, but they were surprised when NASA's Spitzer Space Telescope revealed two rocky rings between the icy halo and the star. | 天文學家們已經(jīng)了解到恒星“E波江”外圍的多冰環(huán)帶，但是當美國國家航空航天管理局的斯必澤太空望遠鏡在這個多冰的暈輪與該恒星之間發(fā)現(xiàn)了兩個巖石環(huán)帶時，他們?nèi)匀桓械胶荏@訝。 |
| The inner asteroid belt looks identical to ours in terms of material, and it orbits at 3 astronomical units (AU) from Epsilon Eridani — the same distance between the sun and the rocky asteroid belt between Mars and Jupiter. An astronomical unit equals the average Earth-sun distance of 93 million miles, or about 150 million km. | 內(nèi)圍小行星帶中的物質看起來跟我們太陽系的小行星帶一模一樣，在3天文單位的距離上環(huán)繞著恒星“E波江”——這個距離跟火星和木星之間的小行星帶到太陽的距離也一樣。1天文單位等于地球跟太陽之間的平均距離，相當于9,300萬英里，或者15,000萬公里。 |
| Epsilon Eridani's second asteroid belt is 20 AU from the star, or about where Uranus is in relation to our sun, and it is crowded with as much mass as Earth's moon. | 恒星“E波江”的第二個小行星帶距離該恒星20天文單位，或者說相當于天王星到太陽的距離，其中所包含的物質質量相當于月球。 |
| The outer icy ring, previously observed, extends about 35 AU to 100 AU from Epsilon Eridani and is similar in composition to our Kuiper Belt, a region of icy objects beyond Neptune. Eridani's outer ring holds about 100 times more material than ours, however. | 以前所觀察到的外圍多冰環(huán)帶到恒星“E波江”的距離從35天文單位到100天文單不等，構成成分與我們太陽系的柯伊伯帶（Kuiper Belt）相同。柯伊伯帶是海王星以外的一個多冰物質區(qū)域帶。然而，“E波江”的外圍環(huán)帶所包含的物質大約是柯伊伯帶的100倍。 |
| New exoplanets? | 存在新的系外行星嗎？ |
| The rings formed when the system was very young, likely when collisions between planets and other smaller bodies resulted in small bits and big chunks of debris that took shape as the asteroid belts and icy ring, the researchers suggest. | 研究人員提出：這些環(huán)帶是該恒星系統(tǒng)很年輕的時候形成的，很可能是行星跟更小的天體相撞造成了大大小小的碎塊殘骸，最后形成了兩個小行星帶和一個多冰環(huán)帶。 |
| And the gaps between these rings were likely shaped by planets whose gravitational forces could remove any excess material flung from the belts, while also keeping the shape of the rings. Planets in our solar system exert similar shaping effects. | 這些環(huán)帶之間的間隙形狀可能是由行星控制的，行星的引力可以清除任何飛離環(huán)帶的多余物質，同時也保持了環(huán)帶的形狀。我們太陽系的行星也發(fā)揮著類似的保持形狀的作用。 |
| "The big planets that are now keeping those gaps are determining the geometry of the system of rings," Marengo told SPACE.com. | “對環(huán)帶間隙起著保持形狀作用的大型行星，也決定著環(huán)帶系統(tǒng)的幾何形狀，”馬倫果告訴《太空網(wǎng)》的記者說。 |
| He and his colleagues propose three planets with masses between those of Neptune and Jupiter could be in orbit about Epsilon Eridani. A Jupiter-mass exoplanet was detected in 2000 by the radial velocity method in which astronomers look for wobbling motion of a star due to the gravitational tug of a planet. That planet is located near the edge of the innermost ring. | 馬倫果及同事提出，可能有三顆質量介于海王星和木星之間的行星位于環(huán)繞恒星“E波江”的軌道上。2000年，曾經(jīng)用徑向速度法發(fā)現(xiàn)了一顆相當于木星質量的系外行星。在徑向速度法中，天文學家們往往尋找恒星擺動的跡象，這種擺動是由于行星的引力作用造成的。那顆行星位于最內(nèi)側的環(huán)帶邊緣處。 |
| A second planet must lurk near the second asteroid belt, and a third at about 35 AU near the inner edge of Epsilon Eridani's Kuiper Belt, the researchers say. Terrestrial planets could reside inside the innermost asteroid belt as well, though there currently is no clear indication of that, Marengo said. | 研究人員稱，第二顆行星肯定潛伏在第二條小行星帶附近，而第三顆行星則潛伏于35天文單位處——恒星“E波江”的“柯伊伯帶”內(nèi)側邊緣附近。馬倫果說，盡管還沒有明確的證據(jù)，但是最內(nèi)側的小行星帶內(nèi)部也可能存在類地行星。 |
| The research will be detailed in the Jan. 10 issue of The Astrophysical Journal. | 該研究將詳細地報到在2009年1月10日出版的《天體物理學雜志》上。 |
