Messier 56

Messier 56
Ilustracja
Gromada kulista Messier 56. Zdjęcie wykonane przez Kosmiczny Teleskop Hubble’a
Odkrywca

Charles Messier

Data odkrycia

23 stycznia 1779

Dane obserwacyjne (J2000)
Gwiazdozbiór

Lutnia

Typ

kulista, klasa X

Rektascensja

19h 16m 35,51s

Deklinacja

+30° 11′ 04,2″

Odległość

32,9 tys. ly (10 kpc)

Jasność obserwowana

8,3 m

Rozmiar kątowy

8,8'

Charakterystyka fizyczna
Wymiary

Ø 85 ly

Alternatywne oznaczenia
M56, NGC 6779, GCl 110, C 1914+300, CSI+30-19146 3, GCRV 11736
Mapa gromady
Konstelacja Lutni

Messier 56 (również M56, NGC 6779) – gromada kulista w gwiazdozbiorze Lutni. Została odkryta 23 stycznia 1779 roku przez Charles’a Messiera, który opisał ją jako „mgławicę bez gwiazd”. Jako gromadę gwiazd po raz pierwszy opisał ją William Herschel około 1784 roku.

M56 znajduje się w odległości ok. 32,9 tys. lat świetlnych od Ziemi i przybliża się z prędkością 145 km/s. Średnica gromady wynosi ok. 85 lat świetlnych.

Najjaśniejsze gwiazdy gromady mają jasność obserwowaną ok. 13m[1]. M56 należy do typu widmowego F5. Do tej pory odkryto około tuzina gwiazd zmiennych należących do M56.

Gromada M56 znajduje się w połowie odległości między gwiazdami Albireo i γ Lyrae.

Zobacz też

Przypisy

  1. Helen Sawyer Hogg podała średnią jasność 15,31m dla 25 najjaśniejszych gwiazd.

Bibliografia

  • Hartmut Frommert, Christine Kronberg: Messier 56 (ang.). W: The Messier Catalog [on-line]. Students for the Exploration and Development of Space (SEDS), 2007-08-30. [dostęp 2015-11-16].

Linki zewnętrzne


Media użyte na tej stronie

Lyra constelation PP3 map PL.jpg
Autor: Oryginalnym przesyłającym był Blueshade z polskiej Wikipedii, Licencja: CC-BY-SA-3.0
Ta mapa gwiazdozbioru została stworzona przy pomocy programu PP3 autorstwa Torstena Brongera. Tłumaczenia na język polski oraz innych modyfikacji na potrzeby polskiej Wikipedii dokonał Przemysław 'BlueShade' Idzkiewicz. Grafika udostępniona jest na licencji GFDL w wersji 1.2 lub nowszej.
Messier 56 HST.jpg
Autor: NASA & ESA. Acknowledgement: Gilles Chapdelaine, Licencja: CC BY 3.0
The NASA/ESA Hubble Space Telescope has produced this beautiful image of the globular cluster Messier 56 (also known as M 56 or NGC 6779), which is located about 33 000 light years away from the Earth in the constellation of Lyra (The Lyre). The cluster is composed of a large number of stars, tightly bound to each other by gravity.

However, this was not known when Charles Messier first observed it in January 1779. He described Messier 56 as “a nebula without stars”, like most globular clusters that he discovered — his telescope was not powerful enough to individually resolve any of the stars visible here, making it look like a fuzzy ball through his telescope’s eyepiece. We clearly see from Hubble’s image how the development of technology over the years has helped our understanding of astronomical objects.

Astronomers typically infer important properties of globular clusters by looking at the light of their constituent stars. But they have to be very careful when they observe objects like Messier 56, which is located close to the Galactic plane. This region is crowded by “field-stars”, in other words, stars in the Milky Way that happen to lie in the same direction but do not belong to the cluster. These objects can contaminate the light, and hence undermine the conclusions reached by astronomers.

A tool often used by scientists for studying stellar clusters is the colour-magnitude (or Hertzsprung-Russell) diagram. This chart compares the brightness and colour of stars – which in turn, tells scientists what the surface temperature of a star is.

By comparing high quality observations taken with the Hubble Space Telescope with results from the standard theory of stellar evolution, astronomers can characterise the properties of a cluster. In the case of Messier 56, this includes its age, which at 13 billion years is approximately three times the age of the Sun. Furthermore, they have also been able to study the chemical composition of Messier 56. The cluster has relatively few elements heavier than hydrogen and helium, typically a sign of stars that were born early in the Universe’s history, before many of the elements in existence today were formed in significant quantities.

Astronomers have found that the majority of clusters with this type of chemical makeup lie along a plane in the Milky Way’s halo. This suggests that such clusters were captured from a satellite galaxy, rather than being the oldest members of the Milky Way's globular cluster system as had been previously thought.

This image consists of visible and near-infrared exposures from Hubble’s Advanced Camera for Surveys. The field of view is approximately 3.3 by 3.3 arcminutes.

A version of this image was entered into the Hubble’s Hidden Treasures Image Processing Competition by contestant Gilles Chapdelaine. Hidden Treasures is an initiative to invite astronomy enthusiasts to search the Hubble archive for stunning images that have never been seen by the general public. The competition has now closed and the results will be published soon.