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Sagittarius A* System

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Sagittarius A* is thought to be the Super Massive Black Hole (SMBH) at the center of our Milky Way galaxy and is 26,000 ly away. (The "*" in its name is pronounced "star" from the symbol, and not used to indicate that this object is a "star".) It forms one component of the larger Sagittarius A structure, a complex radio source that spans light years. The black hole is orbited by about a dozen stars, which tend to have comet-like orbits centered a couple thousand light years from the black hole. These stars orbit faster than any other found (only taking 10 to 100 years to complete their orbits). The orbits of the stars is used to determine that the black hole is 4.1 Million Solar Masses and occupies an area no more than 45 AU (about the size of Neptune's orbit). Streams of gasses also orbit the black hole, which may be the remnants of planets that started forming around its orbiting stars, but then got yanked from their stars when approaching too close to the black hole. The cloud G2 was expected to be destroyed when it approached its closest point to the black hole near its event horizon, but survived its journey unscathed. A magnetar (a type of neutron star with a powerful magnetic field) SGR J1745-2900 was recently discovered orbiting the black star. A possible Intermediate Mass Black Hole (IMBH) GCIRS 13E (1300 MS) orbits the SMBH further out at about 3 light years. This black hole itself has seven massive stars orbiting it. This object might have formed through the collision of several stars in an ancient globular cluster. About 10,000 black holes may orbit SGR A* within 70 light years, being kicked in towards the galactic center during encounters with smaller stars, which in turn get kicked out towards the galactic rim. The SMBH may devour these black holes at about a rate of 1 per million years. Gamma rays emitted by SGR A* caused X-Rays to be emitted from a giant molecular cloud Sagittarius B2 350 ly away. The event horizon is the target of the earth-spanning Event Horizon Telescope.

Sagittarius A* System Web PagesEdit

Wikipedia Pages for Components


Sagittarius A* System In the NewsEdit

Sagittarius A* Discovered as a Point Source (1974)Edit

Jet Model Based on Chandra's Initial X-Ray Observations (Oct 2000)Edit

Closest Approaching Star (S-16) Identified (Jun 2003)Edit

Accretion Flow Models (Nov 2003)Edit

Size of SGA A* 13 RS (Sep 2006)Edit

Chandra Finds Black Hole Consumes Less Than Expected (Jan 2010)Edit

G2 Discovered, Heading Towards Black Hole (Dec 2011)Edit

G2 Could Be Remains of Protoplanetary Disk (Dec 2011)Edit

Flares Caused by Consuming Asteroids? (Feb 2012)Edit

G2 Could Harbor Star (Sep 2012)Edit

NuSTAR Detects Megaflare (Oct 2012)Edit

S0-102 Star With Shortest Period Discovered (Oct 2012)Edit

Sophia Observes Starbursts in Circumnuclear Ring (Jan 2013)Edit

Magnetar Found Close to Black Hole (May 2013)Edit

G2 Cloud Starts Encounter with Black Hole (Jul 2013)Edit

Circumnuclear Ring Imaged by Sophia (Jul 2013)Edit

Inner Spiral Reaches High Speeds (Aug 2013)Edit

Chandra Detects Jet from Black Hole (Nov 2013)Edit

Circumnuclear Ring (CNR), Quintuplet Cluster (QC) and Centrl Cluster Studied (Mar 2014)Edit

Black Hole Could Be Wormhole Instead (May 2014)Edit

Very Long Baseline Array Determines Size of Radio Source (Jul 2014)Edit

G2 Survives Close Encounter with Black Hole (Oct 2014)Edit

NuSTAR Detects Black Hole Reflections From Nearby Clouds (Oct 2014)Edit


G2 Could Be Enshrouded Binary that Merged During Black Hole Encounter (Nov 2014)Edit

Black Hole Could Emit Neutrinos (Nov 2014)Edit

Black Hole Appearance Simulated (Dec 2014)Edit

Pulsar Around Stellar Mass Black Hole True Gravity Theory Holy Grail (Dec 2014)Edit

G1 May Have Followed G2's Path (Dec 2014)Edit

Debate If G2 is Cloud or Binary Star (Jan 2015)Edit

Second X-Ray Megaflare Detected by Chandra (Jan 2015)Edit

X-Ray Flux Distribution with Chandra (Feb 2015)Edit

South Pole Telescope Added to Event Horizon Telescope Array (Apr 2015)Edit

SGR A* Not Cause of Fastest Star US 708's Speed, Which Will Leave Galaxy (Mar 2015)Edit

Supernova Dust Near Black Hole (Mar 2015)Edit

Graveyard of Stars May Surround Black Hole (Apr 2015)Edit

Migration of Black Holes (Jun 2015)Edit

G2 Cloud is Possibly a Protoplanet Remnant (Jun 2015)Edit

Event Horizon Telescope Goals (Jul 2015)Edit

See AlsoEdit

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