B68, the black cloud

This photograph shows an unusual sky field in the Milky Way band. It is centred on one of the classical, dark globules, known as Barnard 68 (B68) after the American astronomer, Edward E. Barnard (1857 - 1923), who included it in a list of such objects, published in 1919. It appears as a compact, opaque and rather sharply defined object against a rich, background star field. Even on this image that registers many faint stars in the area, not a single foreground star is observed. This is a clear sign that this globule must be relatively nearby. Interstellar clouds consist of gas and dust, including many molecules, some of which contain carbon atoms (i.e. organic). For a long time considered to be "holes in the sky", molecular clouds are now known to be among the coolest objects in the Universe (the temperature is approx. 10 K, or -263 °C). Moreover, and most importantly, they are nurseries of stars and planets. It still remains a mystery how a dark cloud like Barnard 68 at some moment begins to contract and subsequently transforms itself into hydrogen-burning stars. However, deep images of these clouds, such as this one obtained by FORS1 on VLT ANTU, may provide important clues. This small cloud seems to be in its very earliest phase of collapse. It has a diameter of only 7 light-months (approx. 0.2 pc) and it is located at a distance of about 500 light-years (160 pc) towards the southern constellation Ophiuchus (The Serpent-holder). This three-colour composite was reproduced from one blue (B), one green-yellow (V) and one near-infrared (I) exposure that were obtained with VLT ANTU and FORS1 in the early morning of March 27, 1999. The field measures 6.8x6.8 arcmin 2. The image consists of 2048x2048 pixels, each measuring 0.20 arcsec; the "Full Resolution" version of the photo shows all of these. North is up and East is to the left. (See also ESO Press Release eso0102.)

Källa:

ESO

Om bilden

ID:eso9924a
Typ:Observation
Publiceringsdatum:30 april 1999
Relaterade pressmeddelanden:eso9924
Storlek:1955 x 1953 px

Om objektet

Namn:B 68, Barnard 68, LDN 57
Typ:Milky Way : Nebula : Appearance : Dark : Bok Globule
Avstånd:500 ljusår
Constellation:Ophiuchus
Kategori:Nebulae

Bildformat

Originalstorlek
10,4 MB
Stor jpeg
2,4 MB
Skärmstor jpeg
542,0 kB

Skrivbordsunderlägg

1024x768
515,7 kB
1280x1024
844,1 kB
1600x1200
1,2 MB
1920x1200
1,4 MB
2048x1536
1,9 MB

Koordinater

Position (RA):17 22 38.23
Position (Dec):-23° 49' 34.69"
Field of view:6.53 x 6.52 arcminutes
Orientering:Nord är 0.1° höger om lodrätt

Färger och filter

BandVåglängdTeleskop
Synligt ljus
B
445 nmVery Large Telescope
FORS1
Synligt ljus
V
547 nmVery Large Telescope
FORS1
Infrarött
I
806 nmVery Large Telescope
FORS1

 

Se även