Available formats: HTML | PDF | (gzipped) PostScript
Dust in the wheel: The Cartwheel galaxy in the Mid-IR *
V. Charmandaris 1,2,
O. Laurent 2,
I.F. Mirabel 2,
P. Gallais 2,
M. Sauvage 2,
L. Vigroux 2,
C. Cesarsky 2 and
P.N. Appleton 3
Received 9 July 1998 / Accepted 13 October 1998
We present mid-infrared images at and of "The Cartwheel" (AM 0035-33), the prototypical collisional ring galaxy. The observations, taken with ISOCAM, reveal the distribution of hot dust in the galaxy and its two companions in the north-east. The intensity of the Mid-IR emission from the outer star forming ring of the Cartwheel shows considerable azimuthal variation and peaks at the most active H region of the ring. The 15 to 6.7 flux ratio of 5.2 is the highest among all the galaxies of our sample. A surprising result of our observations is the discovery of significant emission from the inner regions of the galaxy, including the inner ring, spokes and nucleus, where previously only low level H emission had been reported. At 6.7 , this emission is stronger than the one from the outer star forming ring, and at 15 , it represents 40% of the emission from the outer ring. The H to Mid-IR flux ratios from the inner regions are consistent with the heating of grains from weak star formation activity.
Key words: infrared: ISM: continuum galaxies: starbust galaxies: interactions galaxies: individual: The Cartwheel stars: formation
* Based on observations with ISO, an ESA project with instruments funded by ESA Member States (especially the PI countries: France, Germany, the Netherlands and the United Kingdom) with the participation of ISAS and NASA.
Send offprint requests to: V. Charmandaris (firstname.lastname@example.org)
Online publication: November 26, 1998