NGC 6984
| Galaxie NGC 6984 | |
|---|---|
 (c) ESA/Hubble, CC BY 4.0 | |
| Aufnahme des Hubble-Weltraumteleskops | |
| AladinLite | |
| Sternbild | Indus |
| Position Äquinoktium: J2000.0, Epoche: J2000.0 | |
| Rektaszension | 20h 57m 54s[1] |
| Deklination | −51° 52′ 15″[1] |
| Erscheinungsbild | |
| Morphologischer Typ | SB(r)c[1] |
| Helligkeit (visuell) | 12,5 mag[2] |
| Helligkeit (B-Band) | 13,2 mag[2] |
| Winkelausdehnung | 1,8′ × 1,2′[2] |
| Positionswinkel | 101°[2] |
| Flächenhelligkeit | 13,2 mag/arcmin²[2] |
| Physikalische Daten | |
| Rotverschiebung | 0,015577 ± 0,000030[1] |
| Radialgeschwindigkeit | (4670 ± 9) km/s[1] |
| Hubbledistanz H0 = 73 km/(s • Mpc) | (207 ± 14) · 106 Lj (63,4 ± 4,4) Mpc [1] |
| Geschichte | |
| Entdeckung | John Herschel |
| Entdeckungsdatum | 8. Juli 1834 |
| Katalogbezeichnungen | |
| NGC 6984 • PGC 65798 • ESO 235-020 • IRAS 20543-5203 • 2MASX J20575398-5152151 • SGC 205419-5203.8 • AM 2054-520 • LDCE 1431 NED002 | |
NGC 6984 ist eine Balken-Spiralgalaxie vom Hubble-Typ SBc im Sternbild Indianer am Südsternhimmel. Sie ist schätzungsweise 207 Millionen Lichtjahre von der Milchstraße entfernt und hat einen Durchmesser von etwa 110.000 Lj.
Im selben Himmelsareal befindet sich u. a. die Galaxie NGC 6982.
Das Objekt wurde am 8. Juli 1834 von dem Astronomen John Herschel mit einem 48-cm-Teleskop entdeckt.[3]
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Stellar explosions in NGC 6984.jpg
(c) ESA/Hubble, CC BY 4.0
Supernovae are intensely bright objects. They are formed when a star reaches the end of its life with a dramatic explosion, expelling most of its material out into space. The subject of this new Hubble image, spiral galaxy NGC 6984, played host to one of these explosions back in 2012, known as SN 2012im. Now, another star has exploded, forming supernova SN 2013ek — visible in this image as the prominent, star-like bright object just slightly above and to the right of the galaxy's centre.
(c) ESA/Hubble, CC BY 4.0
Supernovae are intensely bright objects. They are formed when a star reaches the end of its life with a dramatic explosion, expelling most of its material out into space. The subject of this new Hubble image, spiral galaxy NGC 6984, played host to one of these explosions back in 2012, known as SN 2012im. Now, another star has exploded, forming supernova SN 2013ek — visible in this image as the prominent, star-like bright object just slightly above and to the right of the galaxy's centre.
SN 2012im is known as a Type Ic supernova, while the more recent SN 2013ek is a Type Ib. Both of these types are caused by the core collapse of massive stars that have shed — or lost — their outer layers of hydrogen. Type Ic supernovae are thought to have lost more of their outer envelope than Type Ib, including a layer of helium.
The observations that make up this new image were taken on 19 August 2013, and aimed to pinpoint the location of this new explosion more precisely. It is so close to where SN 2012im was spotted that the two events are thought to be linked; the chance of two completely independent supernovae so close together and of the same class exploding within one year of one another is a very unlikely event. It was initially suggested that SN 2013ek may in fact be SN 2012im flaring up again, but further observations support the idea that they are separate supernovae — although they may be closely related in some as-yet-unknown way.