Information from the European Southern Observatory ESO Press Photos 08a-e/99 27 February 1999 For immediate release | |
VLT Photos of NGC 1365 Fine Details in a Barred Galaxy NGC 1365 is one of the most prominent "barred" galaxies in the sky. It is a supergiant galaxy with a diameter of about 200,000 lightyears, seen in the direction of the southern constellation Fornax (The Furnace). It is a major member of the Fornax Cluster of Galaxies . The distance is about 60 million light-years and the recession velocity has been measured as 1632 km/sec. A massive straight bar runs through this galaxy and contains the nucleus at the centre. It consists mostly of older stars that give a reddish colour to the bar. The gravitational perturbation from the bar causes interstellar gas and dust clouds to form a pair of spiral arms that extend from the ends of the bar. Young luminous hot stars, born out of the interstellar clouds, give these arms a prominent appearance and a blue colour. The bar and spiral pattern rotates clockwise, as seen from us. One full turn takes about 350 million years. Various images of NGC 1365 have recently been obtained with the three instruments, FORS1, the Test Camera (TC), and ISAAC, now installed at the VLT UT1. They show the intricate structure of this magnificent galaxy, also in the innermost region, close to the centre. Some of these images are included here.
ESO PR Photo 08a/99 [Preview - JPEG: 800 x 877 pix - 624k] [High-Res - JPEG: 2039 x 2249 pix - 4.3M] |
ESO PR Photo 08b/99 [Preview - JPEG: 800 x 946 pix - 216k] [High-Res - JPEG: 3000 x 3546 pix - 1.8M] | | PR Photo 08a/99 is a true-colour image of the major part of NGC 1365, combined from three exposures with the FORS1 multi-mode instrument at VLT UT1, in the B (blue), V (green) and R (red) optical bands. The exposure times were 360, 180 and 140 seconds, respectively. The image quality is about 0.8 arcsec. The field measures about 7 x 7 arcmin 2. North is up and East is left. | PR Photo 08b/99 was obtained by FORS1 at VLT UT1 through a narrow optical filter that isolates light emitted by hydrogen in the red H-alpha spectral line. It shows predominantly star-forming regions and other emission nebulae, most of which are located in the bar and along the spiral arms. The exposure time was 900 seconds and the image quality is excellent, about 0.36 arcsec. The field measures about 7 x 7 arcmin 2. North is up and East is left. | |
ESO PR Photo 08c/99 [Preview - JPEG: 800 x 951 pix - 160k] [High-Res - JPEG: 3000 x 3567 pix - 952k] |
ESO PR Photo 08d/99 [Preview - JPEG: 800 x 921 pix - 424k] [High-Res - JPEG: 3000 x 3455 pix - 3.0M] | | PR Photo 08c/99 : This view of the inner area of NGC 1365 was obtained through a red (R) optical filter with the VLT Test Camera (TC), mounted at one of the Nasmyth foci of VLT UT1. Dark dust clouds that obscure the light from objects behind them are seen along the bar and spiral arms. The gravitational action of the bar structure drives the large dust lanes into the nuclear region where intense star forming activity takes place. The exposure time was 900 seconds and the image quality is 0.5 arcsec (FWHM). North is up and East is left. | PR Photo 08d/99 : This is an enlargement from Photo 08b/99, obtained by FORS1 in the light of H-alpha emission of ionized hydrogen, and here processed to show the central region of NGC1365 in great detail. The star-forming regions in this area show up as knots. The nucleus itself is very bright. An analysis has shown that the matter density in the very central region is very high and there are motions with internal velocities up to about 2000 km/sec. The nucleus probably contains a very massive black hole. North is to the upper right and East is to the upper left. | |
ESO PR Photo 08e/99 [Preview - JPEG: 800 x 921 pix - 424k] [High-Res - JPEG: 3000 x 3455 pix - 2.9M] | PR Photo 08e/99 : As seen in this composite image, based on exposures in two infrared-wavebands with the ISAAC multi-mode instrument, the nucleus is also very bright in infrared light. Moreover, this infrared view penetrates further into the obscuring dust to reveal several intriguing, red objects. The reddest two to the N-NE coincide with very compact and intense radio sources which are probably supernova remnants. In others, we are seeing the radiation from dust heated by Super Star Clusters. Combination of 15-min Ks (2.16 µm) and L(3.8 µm) band images made with the Long Wavelength arm plus chopping at the telescope secondary mirror. The field is 17 x 16.5 arcsec 2 with North at the top and East to the left. |
Outlook The VLT will be able to observe a substantial number of large and bright galaxies like NGC 1365 in similar detail. In addition to imaging observations, it will also be possible to obtain detailed spectra of many of the brighter, individual stars as well as of the nebulae. It will be of particular interest to compare the properties of such objects with those of similar ones in our own galaxy, the Milky Way. ESO Press Information This is the caption to ESO PR Photo 08a-e/99 . They are issued in conjunction with ESO Press Release 05/99 and may be reproduced, if credit is given to the European Southern Observatory. Note also the comprehensive VLT Information site. © ESO Education & Public Relations Department Karl-Schwarzschild-Strasse 2, D-85748 Garching, Germany ESO Press Information is made available on the World-Wide Web (URL: http://www.eso.org../ ). |
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