A galaxy full of surprises — NGC 3621 is bulgeless but has three central black holes

This image, from ESO’s Very Large Telescope (VLT), shows a truly remarkable galaxy known as NGC 3621. To begin with, it is a pure-disc galaxy. Like other spirals, it has a flat disc permeated by dark lanes of material and with prominent spiral arms where young stars are forming in clusters (the blue dots seen in the image). But while most spiral galaxies have a central bulge — a large group of old stars packed in a compact, spheroidal region — NGC 3621 doesn’t. In this image, it is clear that there is simply a brightening to the centre, but no actual bulge like the one in NGC 6744 (eso1118), for example.

NGC 3621 is also interesting as it is believed to have an active supermassive black hole at its centre that is engulfing matter and producing radiation. This is somewhat unusual because most of these so-called active galactic nuclei exist in galaxies with prominent bulges. In this particular case, the supermassive black hole is thought to have a relatively small mass, of around 20 000 times that of the Sun.

Another interesting feature is that there are also thought to be two smaller black holes, with masses of a few thousand times that of the Sun, near the nucleus of the galaxy. Therefore, NGC 3621 is an extremely interesting object which, despite not having a central bulge, has a system of three black holes in its central region.

This galaxy is located in the constellation of Hydra (The Sea Snake) and can be seen with a moderate-sized telescope. This image, taken using B, V, and I filters with the FORS1 instrument on the powerful VLT, shows striking detail in this odd object and also reveals a multitude of background galaxies. A number of bright foreground stars that belong to our own Milky Way are also visible.

Crediti:

ESO

A proposito dell'immagine

Identificazione:potw1148a
Tipo:Osservazione
Data di pubblicazione:Lunedì 28 Novembre 2011 10:00
Dimensione:2044 x 2044 px

A proposito delll'oggetto

Nome:NGC 3621
Tipo:Local Universe : Galaxy : Type : Spiral
Local Universe : Galaxy : Component : Central Black Hole
Distanza:22 Milione Anni luce
Constellation:Hydra
Categoria:Galaxies

Formati delle immagini

JPEG grande
2,2 MB

Zoom


Sfondi

1024x768
286,5 KB
1280x1024
519,8 KB
1600x1200
876,5 KB
1920x1200
1,1 MB
2048x1536
1,3 MB

Coordinate

Position (RA):11 18 16.56
Position (Dec):-32° 48' 50.91"
Field of view:6.81 x 6.81 arcminutes
Orientazione:Il Nord è a 89.8° a sinistra della verticale

Colori e filtri

BandaTelescopio
Ottico
B
Very Large Telescope
FORS1
Ottico
V
Very Large Telescope
FORS1
Infrarosso
I
Very Large Telescope
FORS1

 

Vedere anche