NGC 6231

NGC 6231
Ilustracja
NGC 6231 i Zeta Scorpii na zdjęciu amatorskim
Odkrywca

Giovanni Hodierna

Data odkrycia

przed 1654

Dane obserwacyjne (J2000)
Gwiazdozbiór

Skorpion

Typ

otwarta, I3p

Rektascensja

16h 54m 10,8s

Deklinacja

–41° 49′ 27″

Odległość

4054 ly (1243 pc[1])

Jasność obserwowana

2,6 m

Rozmiar kątowy

14,0'[1]

Alternatywne oznaczenia
OCL 997, ESO 332-SC6

NGC 6231 (również OCL 997 lub ESO 332-SC6) – gromada otwarta znajdująca się w gwiazdozbiorze Skorpiona[2] w odległości około 4,1 tys. lat świetlnych od Słońca[1].

Zbliżenie gromady z Kosmicznego Teleskopu Hubble’a

Została odkryta przed 1654 rokiem przez Giovanniego Hodiernę, niezależnie odkrył ją Edmond Halley w 1678 roku[2]. Jest zbyt daleko na południu, by mogła znaleźć się w katalogu Messiera. Jej najjaśniejsza gwiazda Zeta Scorpii, gwiazda piątej wielkości, ma pozornego towarzysza czwartej wielkości, znacznie bliższego Ziemi[3].

Zobacz też

Przypisy

  1. ↑ a b c Wilton Dias et al: Catalog of Optically Visible Open Clusters and Candidates. Departamento de Astronomia, 2014-05-24. [dostęp 2014-12-09].
  2. ↑ a b Courtney Seligman: NGC 6231. [w:] Celestial Atlas [on-line]. [dostęp 2014-12-09]. (ang.).
  3. ↑ Encyklopedia Wszechświata. Warszawa: Wydawnictwo Naukowe PWN, 2006, s. 387. ISBN 978-83-01-14848-5.

Linki zewnętrzne

Media użyte na tej stronie

NGC 6231 and ζ Sco AOFPK.jpg
Autor: StudentAstronomyGroupUoC, Licencja: CC BY 4.0
Open cluster NGC 6231, photographed through a Celestron C 9 1/4 Schmidt-Cassegrain. At the bottom of the image are seen ζ1 (right) and ζ2 (left) Scorpii. ζ1 is a hypergiant star and member of the cluster and one of the brightest stars in Milky Way, while ζ2 lies more than 10 times closer.
Caldwell 76 (50291873217).jpg
Autor: NASA Hubble Space Telescope, Licencja: CC BY 2.0

This image captures the shining stars in a portion of the open cluster Caldwell 76, also known as NGC 6231. It combines observations taken at ultraviolet, visible, and infrared wavelengths by Hubble’s Wide Field and Planetary Camera 2. This camera, before it was retired in 2009, was the highest resolution camera on any spacecraft capable of making observations in the far-ultraviolet range of the electromagnetic spectrum. Astronomers used the unique capabilities of the camera to survey Caldwell 76 and five other open clusters in the Milky Way with unprecedented clarity. By probing open clusters in the far-ultraviolet, astronomers were able to more efficiently find white dwarfs (the cores of stars that have shed their gaseous shell) that would be difficult to detect in the cluster using other methods. This was the first far-ultraviolet survey of open clusters in the Milky Way performed at such high resolution.

Caldwell 76 is located in the constellation Scorpius, roughly 5,600 light-years from Earth. First discovered by the Italian astronomer Giovanni Battista Hodierna, it has an apparent magnitude of 2.6 and can be spotted with the naked eye when the skies are dark and clear. The cluster appears as a fuzzy patch of light to the unaided eye, but its individual stars can be resolved using a pair of binoculars. Caldwell 76 is easiest to observe during the winter in the Southern Hemisphere. It can be viewed from low latitudes of the Northern Hemisphere in the summer.

The cluster is a popular target for southern observers because it is a part of the “False Comet” — a group of celestial objects that resembles a comet streaking across Scorpius. Caldwell 76 forms the head of the “comet,” while two other clusters and a cloud of gas and dust, called an emission nebula, form the tail.

Credit: NASA, ESA, and J. Maiz Apellaniz (Centro de Astrobiologia [CSIC/INTA]); Processing: Gladys Kober (NASA/Catholic University of America)

For Hubble's Caldwell catalog website and information on how to find these objects in the night sky, visit: <a href="https://www.nasa.gov/content/goddard/hubble-s-caldwell-catalog" rel="noreferrer nofollow">www.nasa.gov/content/goddard/hubble-s-caldwell-catalog</a>