47 Tucanae

Kugelsternhaufen
47 Tucanae
Aufgenommen mit dem VISTA
Aufgenommen mit dem VISTA
AladinLite
SternbildTukan
Position
Äquinoktium: J2000.0, Epoche: J2000.0
Rektaszension00h 24m 05,67s [1]
Deklination−72° 04′ 52,6″ [1]
Erscheinungsbild
KonzentrationsklasseIII [2]
Helligkeit (visuell)4,91 mag [1]
Helligkeit (B-Band)5,78 mag [1]
Winkelausdehnung30,9′ [3]
Farbexzess
E(B-V) (Rötung)		0,037 mag [4]
Physikalische Daten
ZugehörigkeitMilchstraße
Integrierter SpektraltypG4
Rotverschiebung−0,000062 ± 0,000001
Radialgeschwindigkeit(−18,7 ± 0,2) km/s
Entfernung14,1 kLj [5]
Masse500.000 M☉
Durchmesser120 Lj [3]
Alter11,8 Mrd. Jahre
Metallizität [Fe/H]-0,72
Geschichte
EntdeckungNicolas Louis de Lacaille
Entdeckungsdatum1751
Katalogbezeichnungen
 NGC 104 • C 0021-723 • GCl 1 • ESO 50-SC9 • Mel 1 • Dun 18 • GC 52 • 47 Tucanae • ξ Tucanae • Lac 1 • h 2322

47 Tucanae (auch als NGC 104 bezeichnet) ist nach Omega Centauri der zweithellste Kugelsternhaufen des Himmels und schon mit bloßem Auge als kleines Nebelfleckchen erkennbar. Er ist ein besonders großer, alter Haufen und etwa 15.000 Lichtjahre von der Erde entfernt[6].

Entdeckung und Benennung

Die Bezeichnung 47 Tucanae rührt daher, dass der Sternhaufen aufgrund seines kompakten Aussehens und großer scheinbarer Helligkeit zunächst als Stern angesehen und entsprechend benannt wurde. Näher untersucht hat ihn zunächst 1751 der französische Astronom Nicolas Louis de Lacaille.[7]

Lage und Eigenschaften

(c) ESA/Hubble, CC BY 4.0
Hochaufgelöste Aufnahme des Kugelsternhaufenzentrums erstellt mittels des Hubble-Weltraumteleskops

Von der Erde aus gesehen scheint 47 Tucanae unmittelbar neben der Kleinen Magellanschen Wolke zu liegen, die jedoch um ein Vielfaches weiter entfernt ist. Sichtbar ist er nur von der südlichen Erdhalbkugel aus. Mit einem scheinbaren Durchmesser von 30′ erreicht er eine Helligkeit von 4,9 mag. Innerhalb von ca. 150 Lichtjahren Durchmesser beherbergt der Sternhaufen mehrere Millionen Sterne, darunter etliche rote Riesen[8]. Im Zentrum des Haufens sind die Sterne sehr dicht gepackt und haben teilweise weniger als 0,1 Lichtjahre Abstand voneinander[9].

Langzeitbeobachtungen mit dem Fermi Gamma-ray Space Telescope lassen 47 Tucanae als schwache Quelle von Gammastrahlung erkennen[10], die vermutlich durch Millisekundenpulsare erzeugt wird.

Literatur

  • König, Michael & Binnewies, Stefan (2023): Bildatlas der Sternhaufen & Nebel, Stuttgart: Kosmos, S. 361
Commons: 47 Tucanae – Sammlung von Bildern, Videos und Audiodateien

Einzelnachweise

  1. ↑ a b c SIMBAD-Abfrage
  2. ↑ Harlow Shapley, Helen B. Sawyer: A Classification of Globular Clusters. In: Harvard College Observatory Bulletin. Band 849, 1927, S. 11–14, bibcode:1927BHarO.849...11S.
  3. ↑ a b Students for the Exploration and Development of Space
  4. ↑ NASA/IPAC Extragalactic Database
  5. ↑ http://iopscience.iop.org/0004-637X/533/1/215/pdf/0004-637X_533_1_215.pdf
  6. ↑ http://www.eso.org/public/germany/news/eso1302/
  7. ↑ Seligman
  8. ↑ 47 Tuc - ein großer Kugelsternhaufen – Astronomy Picture of the Day vom 26. August 2008.
  9. ↑ X-Ray Stars of 47 Tuc – Astronomy Picture of the Day vom 21. Juli 2005 (englisch).
  10. ↑ Fermis Gammastrahlen-Himmel – Astronomy Picture of the Day vom 21. März 2009.


Auf dieser Seite verwendete Medien

New VISTA snap of star cluster 47 Tucanae.jpg
Autor/Urheber: ESO/M.-R. Cioni/VISTA Magellanic Cloud survey. Acknowledgment: Cambridge Astronomical Survey Unit, Lizenz: CC BY 4.0
This new infrared image from ESO’s VISTA telescope shows the globular cluster 47 Tucanae in striking detail. This cluster contains millions of stars, and there are many nestled at its core that are exotic and display unusual properties. Studying objects within clusters like 47 Tucanae may help us to understand how these oddballs form and interact. This image is very sharp and deep due to the size, sensitivity, and location of VISTA, which is sited at ESO's Paranal Observatory in Chile.

Globular clusters are vast, spherical clouds of old stars bound together by gravity. They are found circling the cores of galaxies, as satellites orbit the Earth. These star clumps contain very little dust and gas — it is thought that most of it has been either blown from the cluster by winds and explosions from the stars within, or stripped away by interstellar gas interacting with the cluster. Any remaining material coalesced to form stars billions of years ago.

These globular clusters spark a considerable amount of interest for astronomers — 47 Tucanae, otherwise known as NGC 104, is a huge, ancient globular cluster about 15 000 light-years away from us, and is known to contain many bizarre and interesting stars and systems.

Located in the southern constellation of Tucana (The Toucan), 47 Tucanae orbits our Milky Way. At about 120 light-years across it is so large that, despite its distance, it looks about as big as the full Moon. Hosting millions of stars, it is one of the brightest and most massive globular clusters known and is visible to the naked eye [1]. In amongst the swirling mass of stars at its heart lie many intriguing systems, including X-ray sources, variable stars, vampire stars, unexpectedly bright “normal” stars known as blue stragglers (eso1243), and tiny objects known as millisecond pulsars, small dead stars that rotate astonishingly quickly [2].

Red giants, stars that have exhausted the fuel in their cores and swollen in size, are scattered across this VISTA image and are easy to pick out, glowing a deep amber against the bright white-yellow background stars. The densely packed core is contrasted against the more sparse outer regions of the cluster, and in the background huge numbers of stars in the Small Magellanic Cloud are visible.

This image was taken using ESO’s VISTA (Visible and Infrared Survey Telescope for Astronomy) as part of the VMC survey of the region of the Magellanic Clouds, two of the closest known galaxies to us. 47 Tucanae, although much closer than the Clouds, by chance lies in the the foreground of the Small Magellanic Cloud (eso1008), and was snapped during the survey.

VISTA is the world’s largest telescope dedicated to mapping the sky. Located at ESO’s Paranal Observatory in Chile, this infrared telescope, with its large mirror, wide field of view and sensitive detectors, is revealing a new view of the southern sky. Using a combination of sharp infrared images — such as the VISTA image above — and visible-light observations allows astronomers to probe the contents and history of objects like 47 Tucanae in great detail. Notes

[1] There are over 150 globular clusters orbiting our galaxy. 47 Tucanae is the second most massive after Omega Centauri.

[2] Millisecond pulsars are incredibly quickly rotating versions of regular pulsars, highly magnetised, rotating stellar remnants that emit bursts of radiation as they spin. There are 23 known millisecond pulsars in 47 Tucanae — more than in all other globular clusters bar one, Terzan 5.
Caldwell Catalogue.jpg
Autor/Urheber: Roberto Mura, Lizenz: CC BY-SA 3.0
Caldwell Catalogue objects.
Heic1510a.tif
(c) ESA/Hubble, CC BY 4.0
Globular cluster 47 Tucanae


This NASA/ESA Hubble Space Telescope image shows a globular cluster known as NGC 104 — or, more commonly, 47 Tucanae, since it is part of the constellation of Tucana (The Toucan) in the southern sky. After Omega Centauri it is the brightest globular cluster in the night sky, hosting tens of thousands of stars.

Scientists using Hubble observed the white dwarfs in the cluster. These dying stars migrate from the crowded centre of the cluster to its outskirts. Whilst astronomers knew about this process they had never seen it in action, until the detailed study of 47 Tucanae.

Credit:

NASA, ESA, and the Hubble Heritage (STScI/AURA)-ESA/Hubble Collaboration Acknowledgment: J. Mack (STScI) and G. Piotto (University of Padova, Italy) 

About the Object
Distance:	15000 light years
Constellation:	Tucana

Coordinates
Position (RA):	0 24 6.67
Position (Dec):	-72° 4' 52.84"
Field of view:	2.80 x 2.74 arcminutes
Orientation:	North is 14.8° left of vertical

Colours & filters Band	Wavelength	Telescope
Optical I	814 nm	Hubble Space Telescope ACS
Optical V	606 nm	Hubble Space Telescope ACS
Optical B	475 nm	Hubble Space Telescope ACS
Ultraviolet UV	275 nm	Hubble Space Telescope WFC3
.