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Chamaeleon Complex
The Chamaeleon complex is a large star forming region (SFR) at the surface of the Local Bubble that includes the Chamaeleon I, Chamaeleon II, and Chamaeleon III dark clouds. It occupies nearly all of the constellation Chamaeleon and overlaps into Apus, Musca, Carina and Octans. The mean density of X-ray sources is about one source per square degree. Chamaeleon I dark cloud The Chamaeleon I (Cha I) cloud is one of the nearest active star formation regions at ~160 pc. It is relatively isolated from other star-forming clouds, so it is unlikely that older pre-main sequence (PMS) stars have drifted into the field. The total stellar population is 200–300. The Cha I cloud is further divided into the North cloud or region and South cloud or main cloud. HD 97300 emits X-rays, illuminates the reflection nebula IC 2631 and is one of the highest mass members of the Cha I cloud, spectral type B9V, a Herbig Ae/Be star without emission lines. Cha Halpha 1 is an object of spectral type M ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
A Nursery For Unruly Young Stars
A, or a, is the first letter and the first vowel of the Latin alphabet, used in the modern English alphabet, the alphabets of other western European languages and others worldwide. Its name in English is ''a'' (pronounced ), plural ''aes''. It is similar in shape to the Ancient Greek letter alpha, from which it derives. The uppercase version consists of the two slanting sides of a triangle, crossed in the middle by a horizontal bar. The lowercase version can be written in two forms: the double-storey a and single-storey ɑ. The latter is commonly used in handwriting and fonts based on it, especially fonts intended to be read by children, and is also found in italic type. In English grammar, " a", and its variant " an", are indefinite articles. History The earliest certain ancestor of "A" is aleph (also written 'aleph), the first letter of the Phoenician alphabet, which consisted entirely of consonants (for that reason, it is also called an abjad to distinguish it fro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Herbig Ae/Be Star
A Herbig Ae/Be star (HAeBe) is a pre-main-sequence star – a young () star of spectral types A or B. These stars are still embedded in gas-dust envelopes and are sometimes accompanied by circumstellar disks. Hydrogen and calcium emission lines are observed in their spectra. They are 2-8 Solar mass () objects, still existing in the star formation (gravitational contraction) stage and approaching the main sequence (i.e. they are not burning hydrogen in their center). Description In the Hertzsprung–Russell diagram, Herbig Ae/Be stars are located to the right of the main sequence. They are named after the American astronomer George Herbig, who first distinguished them from other stars in 1960. The original Herbig criteria were: * Spectral type earlier than F0 (in order to exclude T Tauri stars), * Balmer emission lines in the stellar spectrum (in order to be similar to T Tauri stars), * Projected location within the boundaries of a dark interstellar cloud (in order to select re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coalsack And Dark Doodad Dark Nebulae
The Coalsack Nebula (Southern Coalsack, or simply the Coalsack) is a prominent dark nebula in the skies, being easily visible to the naked eye as a dark patch obscuring a brief section of Milky Way stars as they cross their southernmost region of the sky, east of Acrux (Alpha Crucis) which is the bright, southern pointer star of the southern cross. It dominates and overspills the southeast corner of what is considered the extent of the constellation Crux at a little less than twice the distance of Acrux, away from Earth. General information The Coalsack Nebula covers nearly 7 ° by 5° and overlaps somewhat with the neighbor constellations Centaurus and Musca. The first observation was reported by Vicente Yáñez Pinzón in 1499. It was named "''il Canopo fosco''" (the dark Canopus) by Amerigo Vespucci and was also called "''Macula Magellani''" (Magellan's Spot) or "''Black Magellanic Cloud''" in opposition to the Magellanic Clouds. The Coalsack is omitted in most of today's st ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dark Doodad Nebula
The Dark Doodad Nebula is a dark nebula near the globular cluster NGC 4372, much closer than the centre of the galaxy and in the galactic plane, having a length of nearly three degrees of arc. Although officially unnamed, this long molecular cloud has come to be known under this name. It can be found in the southern constellation of Musca (the Fly) with strong binoculars. This cloud consists of regions of dense gas and dust, and is one of the closest star forming regions to the Solar System. It was described in ''Sky & Telescope'' as one of the finest dark nebulae—one that is "wonderful, winding, and very definite". Just to the east of the southern end of the Dark Doodad is NGC 4372. It has also been called the Musca nebula and grouped as the Musca-Chamaeleonis Molecular Cloud. History The nebula was catalogued by Aage Sandqvist, astronomer at Stockholm Observatory The Stockholm Observatory ( sv, Stockholms observatorium, 050) is an astronomical observatory and instituti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Einstein Observatory
Einstein Observatory (HEAO-2) was the first fully imaging X-ray telescope put into space and the second of NASA's three High Energy Astrophysical Observatories. Named HEAO B before launch, the observatory's name was changed to honor Albert Einstein upon its successfully attaining orbit. Project conception and design The HEAO Program, High Energy Astronomy Observatory (HEAO) program originated in the late 1960's within the Astronomy Missions Board at NASA, which recommended the launch of a series of satellite observatories dedicated to high-energy astronomy. In 1970, NASA requested proposals for experiments to fly on these observatories, and a team organized by Riccardo Giacconi, Herbert Gursky, George W. Clark, Elihu Boldt, and Robert Novick responded in October 1970 with a proposal for an x-ray telescope. NASA approved four missions in the HEAO program, with the x-ray telescope planned to be the third mission. One of the three missions of the HEAO program was cancelled in F ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
