Z Camelopardalis
| Doppelstern Z Camelopardalis | |||||||||||
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| Gashülle um Z Camelopardalis | |||||||||||
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| AladinLite | |||||||||||
| Beobachtungsdaten Äquinoktium: J2000.0, Epoche: J2000.0 | |||||||||||
| Sternbild | Giraffe | ||||||||||
| Rektaszension | 08h 25m 13,2s [1] | ||||||||||
| Deklination | +73° 06′ 39,3″ [1] | ||||||||||
| Helligkeiten | |||||||||||
| Scheinbare Helligkeit | 11,92 10,0 bis 14,5 mag [1][2] | ||||||||||
| Helligkeit (B-Band) | (11,85 ± 0,07) mag [1] | ||||||||||
| Helligkeit (V-Band) | 10,00 mag [1] | ||||||||||
| Helligkeit (J-Band) | (11,571 ± 0,027) mag [1] | ||||||||||
| Helligkeit (H-Band) | (11,045 ± 0,030) mag [1] | ||||||||||
| Helligkeit (K-Band) | (10,856 ± 0,023) mag [1] | ||||||||||
| G-Band-Magnitude | (12,68 ± 0,04) mag [1] | ||||||||||
| Spektrum und Indices | |||||||||||
| Veränderlicher Sterntyp | UGZ + N [2] | ||||||||||
| B−V-Farbindex | (+1,85) [1] | ||||||||||
| Spektralklasse | pec(UG) + K7 V [2] | ||||||||||
| Astrometrie | |||||||||||
| Radialgeschwindigkeit | (38) km/s [1] | ||||||||||
| Parallaxe | 4,66 ± 0,03 mas [1] | ||||||||||
| Entfernung | (700 ± 5) Lj (215 ± 2) pc | ||||||||||
| Eigenbewegung [1] | |||||||||||
| Rek.-Anteil: | −8,94 ± 0,02 mas/a | ||||||||||
| Dekl.-Anteil: | −19,11 ± 0,03 mas/a | ||||||||||
| Physikalische Eigenschaften | |||||||||||
| Andere Bezeichnungen und Katalogeinträge | |||||||||||
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Z Camelopardalis ist ein kataklysmisch veränderlicher Stern im Sternbild Giraffe in einer Entfernung von etwa 700 Lichtjahren. Das System ist Namensgeber der Z-Camelopardalis-Sterne, einer Untergruppe der Zwergnovae.
Das System zeigt Phasen mit starken Schwankungen der Lichtkurve und dann wieder Phasen mit nahezu konstanter Helligkeit. Es besteht aus einem Weißen Zwerg und einem Hauptreihenstern der Spektralklasse K. Die Helligkeitsschwankungen werden verursacht durch die Akkretion von Materie vom Hauptreihenstern auf den Weißen Zwerg.
Weblinks
- Aaron Price: Z Camelopardalis. Abgerufen am 29. September 2019 (englisch).
- Michael M. Shara: An ancient nova shell around the dwarf nova Z Camelopardalis. Abgerufen am 29. September 2019 (englisch).
Einzelnachweise
Auf dieser Seite verwendete Medien
Opaque red circle
Autor/Urheber: Lithopsian, Lizenz: CC BY-SA 4.0
Light curve of the prototypical Z Camelopardalis variable, showing a characteristic standstill interrupting the regular eruptions.
Autor/Urheber: IAU and Sky & Telescope magazine (Roger Sinnott & Rick Fienberg), Lizenz: CC BY 3.0
IAU Camelopardalis chart
This enhanced image from the far-ultraviolet detector on NASA's Galaxy Evolution Explorer shows a ghostly shell of ionized gas around Z Camelopardalis, a binary, or double-star system featuring a collapsed, dead star known as a white dwarf, and a companion star.
The image was processed to enhance the diffuse emissions from the shell. Z Cam is the bright object near the center of the image. Parts of the shell are seen as a lobe-like, light- blue feature below and to the right of Z Cam, and as two large, light blue, perpendicular lines on the left.
The massive shell around Z Cam provides evidence of material ejected during and swept up by a powerful nova eruption, called a classical nova, which likely occurred a few thousand years ago.
In exploding binary systems, one of the two stars steals material from the other until it builds up to a certain level; at that point, the system erupts in a giant inferno. In the case of Z Cam, the white dwarf is pilfering material from its sedate companion.
There are two classes of exploding binary star systems, or cataclysmic variables: recurrent dwarf novae, which erupt in small, "hiccup-like" blasts episodically, and classical novae, which undergo huge explosions thousands of times more powerful than dwarf novae.
Z Cam was the one of the first known recurrent dwarf novae. Yet the shell of ionized gas around Z Cam detected by the Galaxy Evolution Explorer can only be explained as the remnant of a full-blown classical nova explosion. The discovery of the shell provides the first evidence that some binary systems undergo both types of explosions. Previously, a link between the two types of novae had been predicted, but there was no evidence to support the theory.
The Galaxy Evolution Explorer first began imaging Z Cam in 2003; this image was taken on Jan. 25, 2004. The type of emission found around Z Cam is most easily visible at far- ultraviolet wavelengths.
Most of the background galaxies and stars have been eliminated by the image processing, although a few linger as white spots near the top. The light-blue streaky clump in the bottom right corner is created by ultraviolet light reflected by dust. It is uncertain if Z Cam is the source of the dust-scattered light.