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Quasar
A quasi-stellar radio source ("quasar", /ˈkweɪzɑr/) is a very energetic and distant active galactic nucleus. Quasars are extremely luminous and were first identified as being high redshift sources of electromagnetic energy, including radio waves and visible light, that were point-like, similar to stars, rather than extended sources similar to galaxies.
While the nature of these objects was controversial until as recently as the early 1980s, there is now a scientific consensus that a quasar is a compact region in the center of a massive galaxy surrounding its central supermassive black hole. Its size is 10–10,000 times the Schwarzschild radius of the black hole.
Quasars have a very high redshift. They seem to inhabit the centers of active young galaxies and can emit up to a thousand times the energy output of our entire galaxy. According to Hubble’s law the redshift shows that quasars are very distant and, because of their distance, much older than our universe. The most luminous quasars radiate in excess of the output of one trillion Suns. This radiation is emitted across the spectrum from X-rays to the far-infrared, but have a peak in the ultraviolet-optical bands. Some quasars are strong sources of radio emission and gamma-rays. In early optical images, quasars looked like single points of light. Infrared telescopes and the Hubble Space Telescope have identified the galaxies surrounding the quasars. These galaxies are normally too dim to be seen against the glare of the quasar otherwise.
Quasars are believed to be powered by the accretion of material into centralized supermassive black holes. This makes them luminous versions of active galaxies. Light cannot escape the super massive black holes, so the escaping energy is generated by gravitational stresses and intense friction outside of the event horizon.
Nyanyian dari Bintang
Bintang bisa bernyanyi? Masa'? Baca ajadeh..
Ilmuwan berhasil menangkap nyanyian dari bintang yang sangat jauh dari bumi. Bintang ini bergetar dan mengeluarkan resonansi bunyi mirip alat musik. Penemuan tersebut merupakan bagian dari penelitain terbaru soal perluasan informasi di balik permukaan bintang yang memiliki ukuran dua kali matahari ini.
Astrofisikawan dari Universitas Birmingham dan ilmuwan yang bekerja di NASA telah mengukur perubahan tingkat cahaya bintang KIC 11026764 yang dijuluki Gemma. Mereka menemukan bahwa bintang yang berjarak 3.100 triliun mil dari Bumi ini bergetar agak mirip alat musik akibat fenomena yang disebut " starquakes" atau resonansi (gerakan) dari permukaan ke inti bintang.Dengan menggunakan teknik yang disebut astroseismologi, mereka mampu mendeteksi kedipan cahaya yang disebabkan oleh starquakes dan merekonstruksi suara yang dihasilkan oleh bintang.Dengungan harmonik yang terdengar seperti hembusan angin di atas mikrofon ini mengungkapkan informasi soal struktur internal bintang, ujar asteroseismologist di Birimingham University yang turut andil dalam penelitian ini, Dr Bill Chaplin. Dia mengatakan bahwa getaran ini mampu membantu astronom mempelajari lebih lanjut soal ukuran, umur dan komposisi suatu bintang. Seperti alat musik, bintang-bintang pada dasarnya tidak seragam karena inti mereka.
Oleh karena itu, suara akan terperangkap di lapisan luar dan berorientasi di dalamnya. Chaplin bekerja dengan tim internasional menggunakan data yang ditangkap oleh teleskop Kepler milik NASA yang mencari bintang-bintang di galaksi kita. Para ilmuwan menemukan bahwa mereka juga bisa menggunakan teleskop tersebut untuk mengambil perubahan lain dalam kecerahan disebabkan oleh starquakes. Dengan cara yang sama seperti cello di mana ini memproduksi nada lebih dalam dibandingkan biola, semakin besar bintang maka semakin rendah frekuensi getaran sehingga memungkinkan ilmuwan mengukur bentuk bintang.
Nebula
A nebula (from Latin: "cloud"; pl. nebulae or nebulæ, with ligature or nebulas) is an interstellar cloud of dust, hydrogen, helium and other ionized gases. Originally, nebula was a name for any diffuse astronomical object, including galaxies beyond the Milky Way. The Andromeda Galaxy, for instance, was referred to as the Andromeda Nebula (and spiral galaxies in general as "spiral nebulae") before the true nature of galaxies was confirmed in the early 20th century by Vesto Slipher, Edwin Hubble, et. al. Nebulae are often star-forming regions, such as in the Eagle Nebula. This nebula is depicted in one of NASA's most famous images, the "Pillars of Creation". In these regions the formations of gas, dust, and other materials "clump" together to form larger masses, which attract further matter, and eventually will become massive enough to form stars. The remaining materials are then believed to form planets, and other planetary system objects.
Nebula hypothesis was first put forward by Emanuel Swedenborg (1688-1772) in 1734 and completed by Immanuel Kant (1724-1804) in 1775. Similar hypothesis developed by Pierre Marquis de Laplace independently in 1796. This hypothesis, which is better known as the Kant-Laplace hypothesis Nebula, mentions that in the early stages, Solar System still be smog monster.
Fog is formed from dust, ice, and gas called nebulae, and that most of the elements of hydrogen gas. Possessed gravity causes it to shrink and rotate fog in a certain direction, temperature heat haze, and eventually became a giant star (sun). Giant sun continued to slide and rotate faster, and gas rings and ice thrown around the Sun. Due to gravity, these gases condense in line with the drop in temperature and form planets and outer planets. Laplace argued that the nearly circular-shaped orbit of the planets is a consequence of their formation.
