Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

January 22, 1998

Closer To Beta Pic
Credit: S. R. Heap (LASP/ GSFC), NASA

Explanation: What did our Solar System look like as the planets were forming? Since the 1980s, astronomers have been pointing toward Beta Pictoris, a young, sun-like star a mere 50 light-years distant, as a likely example. Beta Pic is surrounded by a disk of dust which we view nearly edge-on. The dust disk shines by reflected starlight and has been examined with ever increasing detail to search for signs of planetary formation. The trick is to follow the disk as close in to the star as possible, without being overwhelmed by the direct starlight. To make this Hubble Space Telescope image, a coronagraph was used to block the direct starlight and achieve the closest view yet. The false color picture shows the inner section of the dusty disk to within nearly 1.5 billion miles of the star itself, about the scale of the orbit of Uranus. The obvious warp is indirect evidence that a planet now orbits this young sun, slightly inclined to the disk. The planet's gravitational pull would produce the visible distortion.

在行星形成階段的太陽系,其外貌何似? 自1980年代以來,天文學家咸認50光年遠的年輕類太陽恆星繪架β,會是一個很好的範例。 繪架β周圍有盤狀塵埃環繞,而我們的視線近乎側視它。 這個塵埃盤因反射星光而發光,近來受到愈來愈詳細的檢視以搜尋行星形成的跡象。 搜尋的關鍵是檢視最接近恆星、但不被恆星直射星光淹沒的塵埃盤。 為了取得這幅哈伯太空望遠鏡影像,特地使用了掩星盤來遮擋直射的星光,以實現最密近的檢視。 這幅彩色的假色影像,呈現塵埃盤的內圍、離恆星240億公里(大約是天王星軌道)範圍內的區域。 盤面明顯的扭曲是個間接的證據,顯示目前有一顆行星繞行這顆年輕的太陽,而其軌道與盤面有個小交角。 因此,行星的重力牽引可能是造成盤面扭曲的可能原因。(beta Pic / β Pictoris 繪架β、老人增四)

Tomorrow's picture: Jovian Aurora

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