Look up His Majesty in Wiktionary, the free dictionary.

His Majesty may refer to:

• His Majesty (comic opera), a 1897 English comic opera
• His Majesty (band)
• His Majesty (horse) (1968–1995), American Thoroughbred racehorse

See also[link]

• Majesty (disambiguation)
• Her Majesty (disambiguation)

This disambiguation page lists articles associated with the same title. If an internal link led you here, you may wish to change the link to point directly to the intended article.

This article needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. (July 2007)

Eta Carinae, in the constellation of Carina, one of the nearer candidates for a future hypernova

Hypernova (pl. hypernovae) refers to a type of supernova explosion with an energy of over 100 supernovae (over 10⁴⁸ joules); such explosions are believed to be the origin of long-duration gamma-ray bursts.^[1]

The radiation output of a nearby hypernova could likely destroy life on Earth; however, no hypergiant is located close enough to Earth to pose a threat.^[2] A group led by Brian Thomas, an astrophysicist at Washburn University in Kansas, has conjectured that a hypernova may have caused the Ordovician–Silurian mass extinction on Earth 440 million years ago, but there is no unambiguous evidence of it.^[3]

The word collapsar, short for collapsed star, was formerly used to refer to the end product of stellar gravitational collapse, a stellar-mass black hole. The word is sometimes used now to refer to a specific model for the collapse of a fast-rotating star, as discussed below.

Collapsing star[link]

The core of a hypernova collapses directly into a black hole, and two extremely energetic jets of plasma are emitted from its rotational poles at nearly the speed of light. These jets emit intense gamma rays and are a candidate explanation for long-duration gamma-ray bursts. However, hypernovas are not a candidate to explain short-duration gamma-ray bursts, which are apparently not associated with massive stars, since some short bursts appear in regions where there is no new star formation – a necessity since massive stars have short lifetimes and thus must be newly born.

The energy output of a hypernova from a massive star, plus a beaming effect, is needed to explain the observed brightness plus the great distance (up to 10 billion light years, as measured by red shift of afterglow ionization) of long-duration (> 2 seconds) gamma-ray bursts, which requires on the order of 10⁴⁴ joules of gamma radiation emission. Since powerful energy jets would be created along the rotation axis of the black hole, a burst of high-energy radiation would likely appear to an observer in the path of the jet, even at distances that are large fractions of that to the visible edge of the universe. This is one proposed mechanism that accounts for the jets' operation, and which has fairly large currency with the astrophysics community.

To date, hypernovas and long-duration gamma-ray bursts have been seen in stellar nurseries, but none has yet been observed in our own galaxy.

Since stars large enough to collapse directly into a black hole are quite rare, hypernovae would likewise be rare, if they indeed occur. It has been estimated that a hypernova would occur in our galaxy every 200 million years.

In recent years a great deal of observational data on long-duration gamma-ray bursts has significantly increased our understanding of these events and made clear that the collapse model produces explosions that differ only in detail from more or less ordinary supernovae. Nevertheless, they continue sometimes to be referred to in the literature as hypernovae. The word hypernova itself was coined by S.E. Woosley.^[4]

Collapsar is currently used as the name of a hypothetical model where a fast-rotating Wolf-Rayet star with a massive (greater than 30 solar masses) core collapses to form a large, rotating black hole, drawing in the surrounding envelope of stellar matter at relativistic speeds with a Lorentz factor of around 150. These speeds would make collapsars the fastest known celestial objects. They may be considered to be "failed" type Ib supernovae.

A possible example of a collapsar is the unusual supernova Sn1998bw, which was associated with the gamma-ray burst GRB 980425. This was classified as a type Ic supernova due to its distinctive spectral properties in the radio spectrum, indicating the presence of relativistic matter.

Another type of hypernova is a pair-instability supernova, of which SN 2006gy was possibly the first observed example. This supernova event was observed in a galaxy about 240 million light years (72 million parsecs) from Earth. In a pair-instability supernova, the pair production effect causes a sudden pressure drop in the star's core, leading to a rapid partial collapse, which causes a sharp rise in temperature and pressure leading to an explosive thermonuclear burning and complete explosion of the star.

In fiction[link]

Jack McDevitt's science fiction novel The Devil's Eye features a hypernova outside the Milky Way.

The science fiction novel The Forever War describes collapsars as a way to travel faster than light in its universe. They are, however, much smaller in scale and in much greater abundance in the book than they are in reality.

See also[link]

• Gamma-ray burst progenitors
• Quark star

References[link]

Further reading[link]

v t e Star Evolution Formation Pre–main sequence Main sequence Horizontal branch Asymptotic giant branch Dredge-up Instability strip Red clump PG1159 star Mira variable Planetary nebula Protoplanetary nebula Luminous red nova Luminous blue variable Wolf–Rayet star Supernova impostor Supernova Hypernova Hertzsprung–Russell diagram Color–color diagram Protostars Molecular cloud H II region Bok globule Young stellar object Herbig–Haro object Hayashi track Hayashi limit Henyey track Orion T Tauri FU Orionis Herbig Ae/Be Luminosity class Subdwarf Dwarf Blue Red Subgiant Giant Blue Red Bright giant Supergiant Blue Red Yellow Hypergiant Yellow Blue straggler Spectral classification O B A F G K M Be OB Subdwarf B Late-type Peculiar Am Ap/Bp Oscillating Barium Carbon CH Extreme helium Lambda Boötis Lead Mercury-manganese S Shell Technetium Remnants White dwarf Black dwarf Helium planet Neutron star Pulsar Magnetar Stellar black hole Compact star Quark Exotic Stellar core: EF Eridani B Failed and theoretical stars Substellar object Brown dwarf Sub-brown dwarf Planetar Boson star Dark-matter star Quasi-star Thorne–Żytkow object Iron star Nucleosynthesis Alpha process Triple-alpha process Proton–proton chain Helium flash CNO cycle Lithium burning Carbon burning Neon burning Oxygen burning Silicon burning S-process R-process Fusor Nova Remnants Structure Core Convection zone Microturbulence Oscillations Radiation zone Atmosphere Photosphere Starspot Chromosphere Corona Stellar wind Bubble Asteroseismology Eddington luminosity Kelvin–Helmholtz mechanism Properties Designation Dynamics Effective temperature Kinematics Magnetic field Magnitude Absolute Mass Metallicity Rotation UBV color Variability Star systems Binary Contact Common envelope Multiple Accretion disc Planetary system Earth's Solar System Earth-centric observation of Pole star Circumpolar star Magnitude Apparent Extinction Photographic Color Radial velocity Proper motion Parallax Photometric-standard star Lists Star names Arabic Chinese Most massive Least massive Largest Brightest Historical Most luminous Nearest Nearest bright Stars with exoplanets Brown dwarfs Planetary nebulae Novae Notable supernovae Supernova remnants Supernova candidates Timeline of stellar astronomy Related articles Planet Star cluster Association Open cluster Globular cluster Galaxy Supercluster Helioseismology Guest star Constellation Asterism Gravity Intergalactic star Infrared dark cloud Star portal

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Annie Mac
Annie Mac DJing in Brighton
Birth name	Annie MacManus
Born	(1978-07-18) July 18, 1978 (age 33) Dublin, Republic of Ireland
Show	Annie Mac
Station(s)	BBC Radio 1
Time slot	7:00 - 9:00 p.m. Friday
Show	Nick Grimshaw and Annie Mac (Co-presented with Nick Grimshaw)
Station(s)	BBC Radio 1
Time slot	10:00pm - Midnight Sunday
Style	Dance & Entertainment
Country	Ireland/United Kingdom
Website	anniemacpresents.com

Annie Mac (born Annie MacManus; 18 July 1978 in Dublin) is an Irish DJ and television presenter who hosts an eponymous electronic dance music show on BBC Radio 1 in the United Kingdom which airs at 7:00 pm on Friday evenings as well as a Sunday evening show alongside co-presenter Nick Grimshaw.

Personal life[link]

Annie Mac was born in Dublin, Ireland. She studied English Literature at Queens University, in Belfast, Northern Ireland. Annie lives in London with her boyfriend, fellow club and Radio 1 DJ, Toddla T.^[1] Her brother, Davey McManus, was the lead singer and guitarist in The Crocketts.

Career[link]

Annie currently hosts a number of shows on Radio 1. Her main show, Annie Mac's Mash Up, airs 7:00 pm to 9:00 pm on Friday nights. She also hosted BBC Switch with Nick Grimshaw on Sunday evenings from 7:00 pm to 10:00 pm until 21 March 2010. After this date they moved to 10:00pm - midnight with a new show simply called Nick Grimshaw and Annie Mac. She is currently one of only two presenters on the station to present shows in both the specialist and entertainment sector, the other being Huw Stephens.

A popular feature of Annie Mac's Mash Up is the Annie Mac Mini Mix, an opportunity to showcase various DJs ability to produce a five minute mix with other DJs. The Mini mix was also a feature of her previous show on a Thursday night. As well as her own Friday show, Annie also covers for other Radio 1 shows. She is a regular stand in for Zane Lowe's show. In 2009 Annie won the Best female award at the drum and bass awards for her contribution to the promotion of this genre of music.

Annie makes regular appearances as a feature presenter on BBC Two's The Culture Show, giving her opinions on the latest music offerings.^[2] She appeared on Never Mind the Buzzcocks in January 2006 and she co-presented Top Of The Pops on 18 June 2006 with Reggie Yates and on 11 July 2006 with Rufus Hound in a T in the Park special. Annie has also filled in for Zane Lowe on his Gonzo show on MTV2. She regularly DJs at clubs such as Fabric London, Moles Club in Bath, Digital in Brighton and university venues such as Fitzwilliam College, Cambridge and Aston University. She also recently appeared on ITV Comedy, FM, as herself.

On 18 February 2007 BBC Radio 1 launched their first video podcast or vodcast. It featured Annie on a backstage tour around the Radio 1 buildings. This has since been stopped, however there is now a podcast of the Mini Mix.

She has also presented Other Voices for RTÉ Two.^[3]

In September 2009, Mac released her first compilation album, Annie Mac Presents, followed in the two years since by Annie Mac Presents 2010 and Annie Mac Presents 2011.^[4]

References[link]

External links[link]

• Official website
• Annie Mac at BBC Programmes
• Nick Grimshaw & Annie Mac at BBC Programmes
• Annie Mac on Twitter
• Annie Mac on Myspace
• Annie Mac's channel on YouTube
• More Than The Music - Annie Mac (Tess Askew)