Sharpless 264 , also known as the Lambda Orionis Ring , is a molecular cloud and H II region , which can be seen in the northern region of the Orion molecular cloud complex (OMCC), in the constellation of Orion . The OMCC is one of the best-known star formation regions and the closest sector of the Milky Way to the Solar System where high-mass stars are born. The nebula is named after its main star, λ Orionis , a blue giant responsible for the ionization of the surrounding material. It is also sometimes called the Angelfish Nebula due to its resemblance as to its lighter areas (pink to peach colour) to an angelfish . In the infrared its ionized boundaries are that which appears, instead.
16-413: λ Orionis (also known as Meissa or Heka ) at about 1,100 light-years is the star representing the head of Orion and can be found to the north of the quadrangle defined by the stars Betelgeuse , Bellatrix , Rigel and Saiph . This star can be found at the centre of open cluster Collinder 69 composed of fourth and fifth-magnitude young hot stars, visible to the naked eye. It can be resolved with
32-401: A pair of binoculars . The rest of the cluster and associated nebula spans a few hundred light-years centred about 1400 light-years away. The broad nebula shown is not visible unaided, with binoculars or small amateur telescopes . It becomes clear in long-exposure photographs , such as in the first illustration on this page. Orange giant φ Orionis , while appearing to be surrounded by
48-669: A table of the first two batches of names approved by the WGSN; which included Meissa for this star. It is now so entered in the IAU Catalog of Star Names. The original Arabic name for this star, Al Hakah (the source for another name for it, Heka ) refers to the Arabic lunar mansion that includes this star and the two of Phi Orionis ( Al Haḳʽah , 'a White Spot'). In Chinese , 觜宿 ( Zī Sù ), meaning Turtle Beak , refers to an asterism consisting of Meissa and both of Phi Orionis Consequently,
64-480: A very low mass companion that is probably a brown dwarf . Meissa is surrounded by a ring of nebulosity about 12 degrees across. It is thought to be the remains of a supernova explosion, now ionized by the ultraviolet radiation from Meissa itself and some of the surrounding hot stars. This star is the dominant member of a 5-million-year-old star-forming region known as the λ Orionis cluster, or Collinder 69 . The intense ultraviolet energy being radiated by this star
80-433: Is a star in the constellation of Orion . It is a multiple star approximately 1,300 ly away with a combined apparent magnitude of 3.33. The main components are an O8 giant star and a B-class main sequence star, separated by about 4″. Despite Meissa being more luminous and only slightly further away than Rigel, it appears 3 magnitudes dimmer at visual wavelengths, with much of its radiation emitted in
96-427: Is actually a double star with a companion at an angular separation of 4.41 arcseconds along a position angle of 43.12° (as of 1937). This fainter component is of magnitude 5.61 and it has a stellar classification of B0 V, making it a B-type main sequence star . There is an outlying component, Meissa C, which is an F-type main sequence star with a classification of F8 V. This star in turn may have
112-450: Is creating the Sh2-264 H II region in the neighboring volume of space, which in turn is surrounded by an expanding ring of cool gas that has an age of about 2–6 million years. The expansion of this gaseous ring may be explained by a former binary companion of Meissa that became a Type II supernova . Such an event would also explain the star's peculiar velocity with respect to the center of
128-559: The Chinese name for Meissa itself is 觜宿一 ( Zī Sù yī , English: the First Star of Turtle Beak .) Meissa is a giant star with a stellar classification of O8 III and an apparent visible magnitude 3.54. It is an enormous star with about 34 times the mass of the Sun and 13 times the Sun's radius. The outer atmosphere has an effective temperature of around 35,000 K, giving it
144-698: The bipolar outflows characteristic of young stars by being less collimated , although stellar winds are not generally spherically symmetric. Different types of stars have different types of stellar winds. Post- main-sequence stars nearing the ends of their lives often eject large quantities of mass in massive ( M ˙ > 10 − 3 {\displaystyle \scriptstyle {\dot {M}}>10^{-3}} solar masses per year), slow (v = 10 km/s) winds. These include red giants and supergiants , and asymptotic giant branch stars. These winds are understood to be driven by radiation pressure on dust condensing in
160-650: The ultraviolet due to its high temperature. Lambda Orionis is the star's Bayer designation . The traditional name Meissa derives from the Arabic Al-Maisan which means 'The Shining One'. Al-Maisan was originally used for Gamma Geminorum , but was mistakenly applied to Lambda Orionis and the name stuck. In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN) to catalog and standardize proper names for stars. The WGSN's first bulletin of July 2016 included
176-495: The Ring, is merely a foreground object at only about 116 light years from Earth. HD 34989 is a blue-white main sequence star , visible magnified only, just outside the Ring. It has a small nebulous cloud more geared towards the near-infrared than other parts of the neighbouring ionized regions across the Ring. Meissa Meissa / ˈ m aɪ s ə / , designated Lambda Orionis ( λ Orionis , abbreviated Lambda Ori , λ Ori )
SECTION 10
#1733105002436192-459: The characteristic blue glow of a hot O-type star . Meissa is a soft X-ray source with a luminosity of 10 erg s and peak emission in the energy range of 0.2–0.3 keV, which suggests the X-rays are probably being generated by the stellar wind . The stellar wind of Meissa is well characterized by a mass-loss rate of 2.5 × 10 solar masses per year and a terminal velocity of 2,000 km/s . Meissa
208-401: The expanding ring, as the explosion and resulting mass loss could have kicked Meissa out of the system. A potential candidate for the supernova remnant is the neutron star Geminga . However, the last is unlikely given the distance between Geminga and the cluster. Stellar wind A stellar wind is a flow of gas ejected from the upper atmosphere of a star . It is distinguished from
224-474: The high temperature of the corona . Stellar winds from main-sequence stars do not strongly influence the evolution of lower-mass stars such as the Sun. However, for more massive stars such as O stars, the mass loss can result in a star shedding as much as 50% of its mass whilst on the main sequence: this clearly has a significant impact on the later stages of evolution. The influence can even be seen for intermediate mass stars, which will become white dwarfs at
240-453: The resonance absorption lines of heavy elements such as carbon and nitrogen. These high-energy stellar winds blow stellar wind bubbles . G-type stars like the Sun have a wind driven by their hot, magnetized corona . The Sun's wind is called the solar wind . These winds consist mostly of high-energy electrons and protons (about 1 keV ) that are able to escape the star's gravity because of
256-461: The upper atmosphere of the stars. Young T Tauri stars often have very powerful stellar winds. Massive stars of types O and B have stellar winds with lower mass loss rates ( M ˙ < 10 − 6 {\displaystyle \scriptstyle {\dot {M}}<10^{-6}} solar masses per year) but very high velocities (v > 1–2000 km/s). Such winds are driven by radiation pressure on
#435564