A globular cluster’s striking red eye

This Picture of the Week shows the colourful globular cluster NGC 2108. The cluster is nestled within the Large Magellanic Cloud, in the constellation of the Swordfish (Dorado). It was discovered in 1835 by the astronomer, mathematician, chemist and inventor John Herschel, son of the famous William Herschel.

The most striking feature of this globular cluster is the gleaming ruby-red spot at the centre left of the cluster. What looks like the cluster’s watchful eye is actually a carbon star. Carbon stars are almost always cool red giants, with atmospheres containing more carbon than oxygen — the opposite to our Sun. Carbon monoxide forms in the outer layer of the star through a combination of these elements, until there is no more oxygen available. Carbon atoms are then free to form a variety of other carbon compounds, such as C2, CH, CN, C3 and SiC2, which scatter blue light within the star, allowing red light to pass through undisturbed.

This image was captured by the NASA/ESA Hubble Space Telescope’s Advanced Camera for Surveys (ACS), using three different filters.

Credit:

ESA/Hubble & NASA

About the Image

Id:potw1832a
Type:Observation
Release date:6 August 2018, 06:00
Size:3908 x 3110 px

About the Object

Name:NGC 2108
Type:Milky Way : Star : Grouping : Cluster : Globular
Distance:150000 light years
Constellation:Dorado
Category:Star Clusters

Image Formats

Large JPEG
5.5 MB
Screensize JPEG
469.9 KB

Zoomable


Wallpapers

1024x768
448.5 KB
1280x1024
729.4 KB
1600x1200
1.0 MB
1920x1200
1.3 MB
2048x1536
1.7 MB

Coordinates

Position (RA):5 44 6.32
Position (Dec):-69° 10' 28.35"
Field of view:3.25 x 2.59 arcminutes
Orientation:North is 27.6° left of vertical

Colours & filters

BandWavelengthTelescope
Optical
B
435 nm Hubble Space Telescope
ACS
Optical
V
555 nm Hubble Space Telescope
ACS
Optical
I
814 nm Hubble Space Telescope
ACS

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