nova

A nova (PL: novae or novas) is a transient astronomical event that causes the sudden appearance of a bright, apparently "new" star (hence the name "nova", which is Latin for "new") that slowly fades over weeks or months. Causes of the dramatic appearance of a nova vary, depending on the circumstances of the two progenitor stars. All observed novae involve white dwarfs in close binary systems. The main sub-classes of novae are classical novae, recurrent novae (RNe), and dwarf novae. They are all considered to be cataclysmic variable stars.
Classical nova eruptions are the most common type. They are likely created in a close binary star system consisting of a white dwarf and either a main sequence, subgiant, or red giant star. When the orbital period falls in the range of several days to one day, the white dwarf is close enough to its companion star to start drawing accreted matter onto the surface of the white dwarf, which creates a dense but shallow atmosphere. This atmosphere, mostly consisting of hydrogen, is thermally heated by the hot white dwarf and eventually reaches a critical temperature causing ignition of rapid runaway fusion.
The sudden increase in energy expels the atmosphere into interstellar space creating the envelope seen as visible light during the nova event. Such were taken in past centuries to be a new star. A few novae produce short-lived nova remnants, lasting for perhaps several centuries. Recurrent nova processes are the same as the classical nova, except that the fusion ignition may be repetitive because the companion star can again feed the dense atmosphere of the white dwarf.
Novae most often occur in the sky along the path of the Milky Way, especially near the observed Galactic Center in Sagittarius; however, they can appear anywhere in the sky. They occur far more frequently than galactic supernovae, averaging about ten per year in the Milky Way. Most are found telescopically, perhaps only one every 12–18 months reaching naked-eye visibility. Novae reaching first or second magnitude occur only several times per century. The last bright nova was V1369 Centauri reaching 3.3 magnitude on 14 December 2013.

View More On Wikipedia.org
  1. VOANHTU

    PHỤ GIA NOVA - NHÀ CUNG CẤP PHỤ GIA THỰC PHẨM HÀNG ĐẦU VIỆT NAM

    PHỤ GIA NOVA - NHÀ CUNG CẤP PHỤ GIA THỰC PHẨM HÀNG ĐẦU VIỆT NAM Phụ gia NOVA là một trong những công ty hàng đầu tại Việt Nam chuyên cung cấp các sản phẩm phụ gia thực phẩm chất lượng cao. Với nhiều năm kinh nghiệm trong ngành, NOVA đã xây dựng uy tín và danh tiếng vững chắc trong lĩnh vực này...
  2. VOANHTU

    CÁCH LÀM CHẢ QUẾ TẠI NHÀ CHUẨN NGON

    CÁCH LÀM CHẢ QUẾ TẠI NHÀ CHUẨN NGON Việc làm chả quế tại nhà không chỉ mang đến hương vị thơm ngon đặc biệt, sản phẩm tạo ra an toàn chất lượng theo ý bạn mà còn giúp bạn tận hưởng niềm vui của việc nấu ăn và chia sẻ bữa ăn cùng gia đình. Trong bài viết này, chúng ta sẽ tìm hiểu cách làm...
Top