* Astronomy

Blobrana · L

RE: NGC 253

Blobrana · L

A spectacular new image of the Sculptor Galaxy (NGC 253) has been taken with the ESO VISTA telescope at the Paranal Observatory in Chile as part of one of its first major observational campaigns. By observing in infrared light VISTA's view is less affected by dust and reveals a myriad of cooler stars as well as a prominent bar of stars across the central region. The VISTA image provides much new information on the history and development of the galaxy.
The Sculptor Galaxy (NGC 253) lies in the constellation of the same name and is one of the brightest galaxies in the sky. It is prominent enough to be seen with good binoculars and was discovered by Caroline Herschel from England in 1783. NGC 253 is a spiral galaxy that lies about 13 million light-years away. It is the brightest member of a small collection of galaxies called the Sculptor Group, one of the closest such groupings to our own Local Group of galaxies. Part of its visual prominence comes from its status as a starburst galaxy, one in the throes of rapid star formation. NGC 253 is also very dusty, which obscures the view of many parts of the galaxy. Seen from Earth, the galaxy is almost edge on, with the spiral arms clearly visible in the outer parts, along with a bright core at its centre.
Read more

Blobrana · L

The H.E.S.S. telescope system detects high-energy rays from the starburst region of a galactic system outside the Milky Way
Quite a few distant galaxies turn out to be cosmic delivery rooms. Large numbers of massive stars are born in the hearts of these starburst galaxies, and later explode as supernovae. In the remnants they leave behind, particles are accelerated to very high energies. Astrophysicists have now used the H.E.S.S. telescopes to make detailed measurements of the gamma rays from the NGC 253 galaxy. As predicted, these high-energy rays originate from the region of maximum supernova activity close to the centre.

Read more

Blobrana · L

HESS détecte le rayonnement gamma d'une galaxie à flambée d'étoiles
Les régions de formation stellaire dans les galaxies à flambée d'étoiles sont le berceau de nombreuses étoiles massives de faible durée de vie. Leur explosion en supernovae est propice à l'accélération de particules à des énergies élevées. Les télescopes internationaux de la collaboration HESS, qui inclut des chercheurs du CNRS (IN2P3 et INSU) et du CEA, ont permis pour la première fois la détection de l'émission d'une telle galaxie, NGC 253, ainsi que son étude détaillée. Ces observations confirment les prévisions : ce rayonnement provient effectivement de la région la plus active en supernovae de cette galaxie. Cette découverte fait l'objet d'un article qui vient d'être publié dans Science.

Read more (French)

Blobrana · L

Title: Evidence of a pure starburst nature of the nuclear region of NGC 253
Authors: A. Brunthaler (1), P. Castangia (1,2), A. Tarchi (2,3), C. Henkel (1), M. J. Reid (4), H. Falcke (5,6) K. M. Menten (1) ((1) Max-Planck-Institut fuer Radioastronomie, (2) INAF-Osservatorio Astronomico di Cagliari, (3) INAF - Istituto di Radioastronomia Bologna, (4) Harvard-Smithsonian Center for Astrophysics, (5) Radboud Universiteit Nijmegen, (6) ASTRON)

We present high-resolution spectral line and continuum VLBI and VLA observations of the nuclear region of NGC 253 at 22 GHz. While the water vapour masers in this region were detected on arcsecond and milliarcsecond scales, we could not detect any compact continuum emission with a 5 sigma upper limit of ~ 1 mJy. The observations reveal that the water maser emission is not related to a possible low-luminosity active galactic nucleus but is almost certainly associated with star-formation activity. Not detecting any compact continuum source on milliarcsecond scales also questions the presence of a - previously assumed - active nucleus in NGC 253.

Read more (55kb, PDF)

Blobrana · L

Astronomers from the Instituto de Astrofísica de Canarias in Spain used NACO, an adaptive optics instrument on the European Southern Observatory's Very Large Telescope (located in Atacama desert in northern Chile), to study NGC 253 in finer detail in the near-infrared.
Adaptive optics corrects for the blurring effect that Earth's atmosphere can have on images taken by ground-based telescopes. Sensors and deformable mirrors correct distortions of incoming light, producing images as clear as if the telescope were in space.
With its adaptive optics system, NACO revealed features of NGC 253 that were only 11 light-years across.

Read more

Blobrana · L

L'activité frénétique d'usines stellaires poussiéreuses
Grâce à l'oeil perçant en proche infrarouge (Le rayonnement infrarouge (IR) est un rayonnement électromagnétique d'une longueur d'onde supérieure à celle de la...) du VLT (Very Large Telescope), des astronomes ont découvert une multitude de nouvelles jeunes et massives pépinières stellaires dans la galaxie voisine NGC 253. Le centre de cette galaxie semble héberger un jumeau du trou noir supermassif (En astrophysique, un trou noir supermassif est un trou noir dont la masse est d'environ un million à un milliard de...) de notre Voie lactée ( Anciennement, la Voie lactée ne désignait que la bande blanchâtre traversant le ciel nocturne. Il existe plusieurs...).

Read more (French)

Blobrana · L

Zoom into NGC 253

Click to Play | View Details

Blobrana · L

Frantic activity revealed in dusty stellar factories
Thanks to the Very Large Telescope's acute and powerful near-infrared eye, astronomers have uncovered a host of new young, massive and dusty stellar nurseries in nearby galaxy NGC 253. The centre of this galaxy appears to harbour a twin of our own Milky Way's supermassive black hole.
Astronomers from the Instituto de Astrofísica de Canarias (Spain) used NACO, a sharp-eyed adaptive optics instrument on ESO's Very Large Telescope (VLT), to study the fine detail in NGC 253, one of the brightest and dustiest spiral galaxies in the sky. Adaptive Optics (AO) corrects for the blurring effect introduced by the Earth's atmosphere. This turbulence causes the stars to twinkle in a way that delights poets, but frustrates astronomers, since it smears out the images. With AO in action the telescope can produce images that are as sharp as is theoretically possible, as if the telescope were in space.
NACO revealed features in the galaxy that were only 11 light-years across.

"Our observations provide us with so much spatially resolved detail that we can, for the first time, compare them with the finest radio maps for this galaxy - maps that have existed for more than a decade" - Juan Antonio Fernández-Ontiveros, the lead author of the paper reporting the results

Read more