The nucleus of comet Wirtanen

The image reveals a false-colour composite image of the nucleus of Comet Wirtanen (the point of light at the centre), recorded on December 9, 2001, with the FORS2 multi-mode instrument at the 8.2-m VLT YEPUN Unit Telescope. It is based on four exposures and since the telescope was set to track the motion of the comet in the sky, the images of stars in the field are seen as four consecutive trails.

The measured brightness and the fact that the image of the comet's 'dirty snowball' nucleus is almost star-like indicates that it is surrounded by a very small amount of gas or dust. The diameter of the nucleus is about 1 km and the distance to the comet from the Earth was ~534 million km.

The comet was located in the southern constellation of Sagittarius, rather low over the western horizon. The first two exposures were made through a standard R-filter and lasted 300s each (airmass 2.4 - 2.5); they were followed by two V-exposures of 250 (airmass 2.7) and 200 (2.8) seconds, respectively. The seeing at this low altitude was 1.0 - 1.2 arcsec. The measured magnitudes of the nucleus were R = 22.6 and V = 23.4 (both ± 0.1). North is up and east is to the left. The field measures approx. 2.0 x 2.0 arcmin 2 ; 1 pixel = 0.2 arcsec.



Sobre a imagem

Data de divulgação:26 de Fevereiro de 2002
Notícias relacionadas:eso0206
Tamanho:512 x 490 px

Sobre o objeto

Nome:Comet Wirtanen
Tipo:Solar System : Interplanetary Body : Comet
Categoria:Solar System

Formatos de imagens

JPEG grande
514,7 KB

Papéis de parede

572,8 KB
782,2 KB
963,5 KB
1007,2 KB
1,3 MB

Cores e filtros

Very Large Telescope