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17-480: M99 or M-99 may refer to: Places [ edit ] M-99 (Michigan highway) , a state highway in south central Michigan Messier 99 , an unbarred spiral galaxy approximately 60 million light-years away in the constellation Coma Berenices M99 road (Johannesburg) , Metropolitan route in the City of Johannesburg, South Africa Rifles [ edit ] Barrett M99 ,

34-544: A supernova is observed, it can be categorized in the Minkowski – Zwicky supernova classification scheme based upon the absorption lines that appear in its spectrum . A supernova is first categorized as either a Type I or Type II , then subcategorized based on more specific traits. Supernovae belonging to the general category Type I lack hydrogen lines in their spectra; in contrast to Type II supernovae which do display lines of hydrogen. The Type I category

51-471: A companion. The progenitors of Types Ib and Ic have lost most of their outer envelopes due to strong stellar winds or else from interaction with a close companion of about 3–4  M ☉ . Rapid mass loss can occur in the case of a Wolf–Rayet star , and these massive objects show a spectrum that is lacking in hydrogen. Type Ib progenitors have ejected most of the hydrogen in their outer atmospheres, while Type Ic progenitors have lost both

68-421: A pure spiral shape with loosely wound arms . It has a peculiar shape with one normal looking arm and an extended arm that is less tightly wound. The galaxy is inclined by 42° to the line-of-sight with a major axis position angle of 68°. A bridge of neutral hydrogen gas links NGC 4254 with VIRGOHI21 , an HI region and a possible dark galaxy . The gravity from the latter may have distorted M99 and drawn out

85-485: A similar operating mechanism, Type Ibc and the various Type II supernovae are collectively called core-collapse supernovae. In particular, Type Ibc may be referred to as stripped core-collapse supernovae . The light curves (a plot of luminosity versus time) of Type Ib supernovae vary in form, but in some cases can be nearly identical to those of Type Ia supernovae. However, Type Ib light curves may peak at lower luminosity and may be redder. In

102-426: A sniper rifle Zijiang M99 , a Chinese anti-materiel rifle Tranquilizer [ edit ] Etorphine (a.k.a. Immobilon or M99), a veterinary tranquilizer [REDACTED] Topics referred to by the same term This disambiguation page lists articles associated with the same title formed as a letter–number combination. If an internal link led you here, you may wish to change the link to point directly to

119-563: A very hot, massive star reaches a point in its evolution when significant mass loss is occurring from its stellar wind. Highly massive stars (with 25 or more times the mass of the Sun ) can lose up to 10 solar masses ( M ☉ ) each year—the equivalent of 1  M ☉ every 100,000 years. Type Ib and Ic supernovae are hypothesized to have been produced by core collapse of massive stars that have lost their outer layer of hydrogen and helium, either via winds or mass transfer to

136-464: Is some evidence that a small fraction of the Type ;Ic supernovae may be the progenitors of gamma ray bursts (GRBs); in particular, type Ic supernovae that have broad spectral lines corresponding to high-velocity outflows are thought to be strongly associated with GRBs. However, it is also hypothesized that any hydrogen-stripped Type Ib or Ic supernova could be a GRB, dependent upon the geometry of

153-499: Is subdivided into Type Ia, Type Ib and Type Ic. Type Ib/Ic supernovae are distinguished from Type Ia by the lack of an absorption line of singly ionized silicon at a wavelength of 635.5  nanometres . As Type Ib and Ic supernovae age, they also display lines from elements such as oxygen , calcium and magnesium . In contrast, Type Ia spectra become dominated by lines of iron . Type Ic supernovae are distinguished from Type Ib in that

170-433: The infrared portion of the spectrum, the light curve of a Type Ib supernova is similar to a Type II-L light curve. Type Ib supernovae usually have slower decline rates for the spectral curves than Ic. Type Ia supernovae light curves are useful for measuring distances on a cosmological scale. That is, they serve as standard candles . However, due to the similarity of the spectra of Type Ib and Ic supernovae,

187-466: The stellar core collapse of massive stars . These stars have shed or been stripped of their outer envelope of hydrogen , and, when compared to the spectrum of Type Ia supernovae , they lack the absorption line of silicon. Compared to Type Ib, Type Ic supernovae are hypothesized to have lost more of their initial envelope, including most of their helium. The two types are usually referred to as stripped core-collapse supernovae . When

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204-739: The encounter. M99 is likely entering the Virgo Cluster for the first time bound to the periphery of the cluster at a projected separation of 3.7°, or around one megaparsec, from the cluster center at Messier 87 . The galaxy is undergoing ram-pressure stripping of much of its interstellar medium as it moves through the intracluster medium . Four supernovae have been observed in this galaxy: SN 1967H ( type II , mag. 14.6), SN 1972Q (type unknown, mag. 15.8), SN 1986I (type II, mag. 14), and SN 2014L ( type Ic , mag. 15.4). Type Ib and Ic supernovae Type Ib and Type Ic supernovae are categories of supernovae that are caused by

221-525: The explosion. In any case, astronomers believe that most Type Ib, and probably Type Ic as well, result from core collapse in stripped, massive stars, rather than from the thermonuclear runaway of white dwarfs . As they are formed from rare, very massive stars, the rate of Type Ib and Ic supernova occurrence is much lower than the corresponding rate for Type II supernovae. They normally occur in regions of new star formation, and are extremely rare in elliptical galaxies . Because they share

238-448: The former also lack lines of helium at 587.6 nm. Prior to becoming a supernova, an evolved massive star is organized like an onion, with layers of different elements undergoing fusion. The outermost layer consists of hydrogen, followed by helium, carbon, oxygen, and so forth. Thus when the outer envelope of hydrogen is shed, this exposes the next layer that consists primarily of helium (mixed with other elements). This can occur when

255-519: The gas bridge, as the two galaxy-sized objects may have had a close encounter before parting greatly. However, VIRGOHI21 may instead be tidal debris from an interaction with the lenticular galaxy NGC 4262 some 280 million years ago. It is expected that the drawn out arm will relax to match the normal arm once the encounter is over. While not classified as a starburst galaxy , M99 has a star formation activity three times larger than other galaxies of similar Hubble type that may have been triggered by

272-507: The hydrogen and helium shells; in other words, Type Ic have lost more of their envelope (i.e., much of the helium layer) than the progenitors of Type Ib. In other respects, however, the underlying mechanism behind Type Ib and Ic supernovae is similar to that of a Type II supernova, thus placing Types Ib and Ic between Type Ia and Type II. Because of their similarity, Type Ib and Ic supernovae are sometimes collectively called Type Ibc supernovae. There

289-423: The intended article. Retrieved from " https://en.wikipedia.org/w/index.php?title=M99&oldid=1088368108 " Category : Letter–number combination disambiguation pages Hidden categories: Short description is different from Wikidata All article disambiguation pages All disambiguation pages Messier 99 This galaxy has a morphological classification of SA(s)c, indicating

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