Astron

Betelgeuse, also designated Alpha Orionis (α Orionis, abbreviated Alpha Ori, α Ori), is the ninth-brightest star in the night sky and second-brightest in the constellation of Orion . Distinctly reddish, it is a semiregular variable star whose apparent magnitude varies between 0.0 and 1.3, the widest range of any first-magnitude star . Betelgeuse is one of three stars that make up the Winter Triangle asterism, and it marks the center of the Winter Hexagon . It would be the brightest star in the night sky if the human eye could view all wavelengths of radiation. https://en.wikipedia.org/wiki/Betelgeuse   Portal  

Sigma Orionis or Sigma Ori (σ Orionis, σ Ori) is a multiple star system in the constellation Orion , consisting of the brightest members of a young open cluster . It is found at the eastern end of the belt , south west of Alnitak and west of the Horsehead Nebula which it partially illuminates. The total brightness of the component stars is magnitude 3.80. https://en.wikipedia.org/wiki/Sigma_Orionis   Portal  

Abstract (from CDS ): We study the record of star formation activity within the dense cluster associated with the Orion Nebula. The bolometric luminosity function of 900 visible members is well matched by a simplified theoretical model for cluster formation. This model assumes that stars are produced at a constant rate and distributed according to the field-star initial mass function. Our best-fit age for the system, within this framework, is 2x10 6 yr. To undertake a more detailed analysis, we present a new set of theoretical pre-main-sequence tracks. These cover all masses from 0.1 to 6.0 M ☉ , and start from a realistic stellar birthline. The tracks end along a zero-age main-sequence that is in excellent agreement with the empirical one. As a further aid to cluster studies, we offer an heuristic procedure for the correction of pre-main-sequence luminosities and ages to account for the effects of unresolved binary companions. The Or...

The Trapezium or Orion Trapezium Cluster, also known by its Bayer designation of Theta 1 Orionis, is a tight open cluster of stars in the heart of the Orion Nebula , in the constellation of Orion . It was discovered by Galileo Galilei . On February 4, 1617 he sketched three of the stars (A, C, D), but missed the surrounding nebulosity. [2] [3] [4] The fourth component (B) was identified by several observers in 1673, and several more components were discovered later, for a total of eight by 1888. Subsequently several of the stars were determined to be binaries. Telescopes of amateur astronomers from about 5 inch aperture can resolve six stars under good seeing conditions. [5] The Trapezium is a relatively young cluster that has formed directly out of the parent nebula. The five brightest stars are on the order of 15-30 solar masses in size. They are within a diameter of 1.5 light-years of each other and are responsible for much of the illumination of the surround...

https://in-the-sky.org/data/constellation.php?id=61  (data tables) Portal

The Orion Nebula (also known as Messier 42, M42, or NGC 1976) is a diffuse nebula situated in the Milky Way , being south of Orion's Belt in the constellation of Orion . [b] It is one of the brightest nebulae , and is visible to the naked eye in the night sky. M42 is located at a distance of 1,344 ± 20 light years [3] [6] and is the closest region of massive star formation to Earth . The M42 nebula is estimated to be 24 light years across. It has a mass of about 2000 times the mass of the Sun. Older texts frequently refer to the Orion Nebula as the Great Nebula in Orion or the Great Orion Nebula. [7] The Orion Nebula is one of the most scrutinized and photographed objects in the night sky, and is among the most intensely studied celestial features. [8] The nebula has revealed much about the process of how stars and planetary systems are formed from collapsing clouds of gas and dust. Astronomers have directly observed protoplanetary disks , brown dwarfs , intense an...

A new view of the Orion Nebula, the "deepest and most comprehensive view ever," reveals a preponderance of low-mass, planet-size objects in the famous star-forming region. The new images,  which you can tour in this awesome new video , use infrared data from European Southern Observatory's (ESO) Very Large Telescope to document the nebula's thick, glowing cloud of gas. With the hawk-like gaze of the telescope's HAWK-1 camera, researchers found 10 times more planet-mass objects and nearly planet-mass failed stars called brown dwarfs  than ever seen before. http://www.space.com/33392-orion-nebula-deepest-view-yet-photos-video.html