Carina-Zwerggalaxie

Galaxie
Carina-Zwerggalaxie
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Vorlage:Skymap/Wartung/Car
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Carina-Zwerggalaxie aufgenommen mit dem Wide Field Imager auf dem MPG/ESO-2,2-m-Teleskop des La-Silla-Observatoriums und vom Victor-M.-Blanco-4-Meter-Teleskop des Cerro Tololo Inter-American Observatory[1]
Carina-Zwerggalaxie aufgenommen mit dem Wide Field Imager auf dem MPG/ESO-2,2-m-Teleskop des La-Silla-Observatoriums und vom Victor-M.-Blanco-4-Meter-Teleskop des Cerro Tololo Inter-American Observatory[1]
AladinLite
SternbildKiel des Schiffs
Position
Äquinoktium: J2000.0, Epoche: J2000.0
Rektaszension06h 41m 36,7s[2]
Deklination-50° 57′ 58″ [2]
Erscheinungsbild
Morphologischer TypdE3/dSph  [2]
Helligkeit (B-Band)11,3 mag
Winkel­ausdehnung23,4′ × 15,5′ [2]
Physikalische Daten
ZugehörigkeitLokale Gruppe  
Radial­geschwin­digkeit(230 ± 60) km/s  [2]
Entfernung(326.000 ± 32.000) Lj /
(100.000 ± 10.000) pc [3][4]
Geschichte
EntdeckungCannon et al[5][6]
Entdeckungsdatum1977[5]
Katalogbezeichnungen
PGC 19441 • ESO 206-G20 •

Die Carina-Zwerggalaxie, auch bekannt als ESO 206-G20 oder PGC 19441, ist eine Zwerggalaxie frühen morphologischen Typs im Sternbild Kiel des Schiffs (lateinisch Carina). Im Jahr 1977 wurde sie mit dem UK-Schmidt-Teleskop am Siding-Spring-Observatorium von der Forschergruppe Cannon et al. entdeckt.[7][8]

Eigenschaften

Als einer der Trabanten der Milchstraße entfernt sich der Carina-Zwerg mit einer Geschwindigkeit von etwa 230 km/s.

Die Galaxie scheint sich erst etliche Milliarden Jahre nach den anderen Satellitengalaxien der Milchstraße gebildet zu haben: ihre ältesten Sterne haben ein relativ geringes Alter von unter 7 Milliarden Jahren.[9] Dies macht sie zu einer relativ jugendlichen Galaxie im Vergleich zur Milchstraße, die mit 13,6 Milliarden Jahren beinahe so alt ist wie das Universum selbst.

Trotz dieser etwas kürzeren Entwicklung hat die Carina-Zwerggalaxie wahrscheinlich eine komplexe Sternentstehungshistorie aufzuweisen; mindestens drei unterscheidbare Sternentstehungsphasen konnten für sie identifiziert werden.[10]

Durch die Nähe zur Milchstraße wird sie von Gezeitenkräften derart heftig verformt, dass sie einen Schweif aus Gas, Staub und Sternen hinter sich herzieht.[11]

Siehe auch

Weblinks

Commons: Sternbild Kiel des Schiffs – Sammlung von Bildern, Videos und Audiodateien

Einzelnachweise

  1. ↑ Hiding in Plain Sight — the elusive Carina Dwarf Galaxy. In: ESO Picture of the Week. European Southern Observatory, abgerufen am 28. Juni 2011.
  2. ↑ a b c d NASA/IPAC Extragalactic Database
  3. ↑ I. D. Karachentsev, V. E. Karachentseva, W. K. Hutchmeier, D. I. Makarov: A Catalog of Neighboring Galaxies. In: Astronomical Journal. 127, Nr. 4, 2004, S. 2031–2068. bibcode:2004AJ....127.2031K. doi:10.1086/382905.
  4. ↑ Karachentsev, I. D.; Kashibadze, O. G.: Masses of the local group and of the M81 group estimated from distortions in the local velocity field. In: Astrophysics. 49, Nr. 1, 2006, S. 3–18. bibcode:2006Ap.....49....3K. doi:10.1007/s10511-006-0002-6.
  5. ↑ a b Carina Dwarf. Abgerufen am 13. Oktober 2007.
  6. ↑ R. D. Cannon, T. G. Hawarden, S. B. Tritton, Hawarden, Tritton: A new Sculptor-type dwarf elliptical galaxy in Carina. In: Monthly Notices of the Royal Astronomical Society. 180, 1977, S. 81–82. bibcode:1977MNRAS.180P..81C.
  7. ↑ Carina Dwarf. Abgerufen am 13. Oktober 2007.
  8. ↑ R. D. Cannon, T. G. Hawarden, S. B. Tritton, Hawarden, Tritton: A new Sculptor-type dwarf elliptical galaxy in Carina. In: Monthly Notices of the Royal Astronomical Society. 180, 1977, S. 81–82. bibcode:1977MNRAS.180P..81C.
  9. ↑ The Satellite Galaxies
  10. ↑ Dennise Hurley-Keller, Mario Mateo and James Nemec: The Star Formation History of the Carina Dwarf Galaxy. In: The Astronomical Journal. 115, 1998, S. 1840. arxiv:astro-ph/9804058. bibcode:1998AJ....115.1840H. doi:10.1086/300326.
  11. ↑ JR Kuhn, Horace A Smith and Suzanne L Hawley: Tidal Disruption and Tails from the Carina Dwarf Spheroidal Galaxy. In: The Astrophysical Journal. 469, 1996, S. L93-L96. bibcode:1996ApJ...469L..93K. doi:10.1086/310270.

Auf dieser Seite verwendete Medien

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Carina constellation map.png
Autor/Urheber: unknown, Lizenz: CC-BY-SA-3.0
Milky Way 2005.jpg

Caption from NASA: Like early explorers mapping the continents of our globe, astronomers are busy charting the spiral structure of our galaxy, the Milky Way. Using infrared images from NASA's Spitzer Space Telescope, scientists have discovered that the Milky Way's elegant spiral structure is dominated by just two arms wrapping off the ends of a central bar of stars. Previously, our galaxy was thought to possess four major arms.

This artist's concept illustrates the new view of the Milky Way, along with other findings presented at the 212th American Astronomical Society meeting in St. Louis, Mo. The galaxy's two major arms (Scutum-Centaurus and Perseus) can be seen attached to the ends of a thick central bar, while the two now-demoted minor arms (Norma and Sagittarius) are less distinct and located between the major arms. The major arms consist of the highest densities of both young and old stars; the minor arms are primarily filled with gas and pockets of star-forming activity.

The artist's concept also includes a new spiral arm, called the "Far-3 kiloparsec arm," discovered via a radio-telescope survey of gas in the Milky Way. This arm is shorter than the two major arms and lies along the bar of the galaxy.

Our sun lies near a small, partial arm called the Orion Arm, or Orion Spur, located between the Sagittarius and Perseus arms.
Carina Dwarf Galaxy.jpg
Autor/Urheber: ESO/G. Bono & CTIO, Lizenz: CC BY 3.0
It’s one of the closest galaxies to Earth, but the Carina Dwarf Galaxy is so dim and diffuse that astronomers only discovered it in the 1970s. A companion galaxy of the Milky Way, this ball of stars shares features with both globular star clusters and much larger galaxies.

Astronomers believe that dwarf spheroidal galaxies like the Carina Dwarf are very common in the Universe, but they are extremely difficult to observe. Their faintness and low star density mean that it is easy to simply see right through them. In this image, the Carina Dwarf appears as many faint stars scattered across most of the central part of the picture. It is hard to tell apart stars from the dwarf galaxy, foreground stars within the Milky Way and even faraway galaxies that poke through the gaps: the Carina Dwarf is a master of cosmic camouflage.

The Carina Dwarf’s stars show an unusual spread of ages. They appear to have formed in a series of bursts, with quiet periods lasting several billion years in between them. It lies around 300 000 light-years from Earth, which places it further away than the Magellanic Clouds (the nearest galaxies to the Milky Way), but significantly closer to us than the Andromeda Galaxy, the closest spiral galaxy.

So, despite being small for a galaxy, its proximity to Earth means that the Carina Dwarf appears quite large in the sky, just under half the size of the full Moon — albeit very much fainter. This makes it fit comfortably within the field of view of ESO’s Wide Field Imager, an instrument designed for making observations of large parts of the sky. Although this image in itself is not so striking, it is likely the best image of the Carina Dwarf Galaxy to date.

The image was made using observations from the Wide Field Imager on the MPG/ESO 2.2-metre telescope at La Silla, and from the Victor M. Blanco 4-metre telescope at the Cerro Tololo Inter-American Observatory.