This Calar Alto image offers one of the best snapshots ever obtained of this stellar system. It was produced with the camera LAICA attached to the 3.5 m telescope of Calar Alto Observatory. The warped disk of NGC 7331 shows its outstanding spiral structure shinning behind a number of stars belonging to our Galaxy, and in front of a rich background populated by an overwhelming variety of distant galaxies. A good fraction of the field of view is occupied by a thin haze of the ghostly, fuzzy and dusty nebulae known as galactic cirrus.
From galactic cirrus to stars and galaxies
Galactic cirrus are diffuse clouds made up from dust, complex organic molecules and gas. Normal reflection nebulae are strongly lighted by one or several close and hot stars, but galactic cirrus shine due to the reflection of faint and diffuse light coming from the Galaxy as a whole. These structures, better seen in the lower part of the image, have been caught thanks to the darkness of Calar Alto skies, to the quality of the instruments used and thanks to the complex and careful method applied to process the data. Vicent Peris, author of this image, explains that " good data and careful digital processing allow to assert that all diffuse traits in the image are real, with the only exception of the bluish halo around the brightest star".
This image is outstanding first and foremost for the variety of objects that it contains. It will be a good challenge for astronomers to get the nature of each of these bodies, from point-like foreground stars to faint background galaxies, and to the intricate structure of the main galaxy.
Image processing: shapes and colour
Good image processing should not benefit one kind of objects at the expense of others but, instead, it has to aim at an equilibrium. To reach this goal, the image of NGC 7331 has been processed using wavelet techniques, a mathematical procedure that allows the separation of structures present in the image according to their characteristic sizes, hence allowing an individual processing to each level. The final result significantly improves the original quality. That is why this image contains accurate representations of objects as different as the foreground nebulae (belonging, as all individual stars, to our own Galaxy) or the external haloes of small and big galaxies, and the internal structures of all of them.
Colour is, also, a very important side of this photograph. The chromatic balance has been obtained assuming that all the light coming from the main galaxy, as a whole, is white. This reference allows to distinguish which parts of NGC 7331 are bluer or redder. This also makes possible to compare the hue of the main galaxy with that of its smaller neighbours and background objects.
The image was obtained with the LAICA (Large Area Imager for Calar Alto) camera attached to the prime focus of the 3.5 m Zeiss telescope of Calar Alto Observatory. The view corresponds to one of the four detectors of this camera and covers an apparent field of view of 15 × 15 arcminutes. North is up, East is left [North is right, East is up, if the image is rotated]. The picture is composed from different individual shots through Johnson filters B and V, and Sloan r' (5 images of 10 minutes and 3 of 1 minute both in B and r', plus 3 shots of 10 minutes and 3 of 1 minute in V: 2 hours and 19 minutes as total integration time).
The observations were planned by Vicent Peris, who also processed the images with the software PixInsight. The data were taken by Gilles Bergond.
David Galadi-Enriquez | alfa
One-way roads for spin currents
23.05.2018 | Singapore University of Technology and Design
Tunable diamond string may hold key to quantum memory
23.05.2018 | Harvard John A. Paulson School of Engineering and Applied Sciences
At the LASYS 2018, from June 5th to 7th, the Laser Zentrum Hannover e.V. (LZH) will be showcasing processes for the laser material processing of tomorrow in hall 4 at stand 4E75. With blown bomb shells the LZH will present first results of a research project on civil security.
At this year's LASYS, the LZH will exhibit light-based processes such as cutting, welding, ablation and structuring as well as additive manufacturing for...
There are videos on the internet that can make one marvel at technology. For example, a smartphone is casually bent around the arm or a thin-film display is rolled in all directions and with almost every diameter. From the user's point of view, this looks fantastic. From a professional point of view, however, the question arises: Is that already possible?
At Display Week 2018, scientists from the Fraunhofer Institute for Applied Polymer Research IAP will be demonstrating today’s technological possibilities and...
So-called quantum many-body scars allow quantum systems to stay out of equilibrium much longer, explaining experiment | Study published in Nature Physics
Recently, researchers from Harvard and MIT succeeded in trapping a record 53 atoms and individually controlling their quantum state, realizing what is called a...
The historic first detection of gravitational waves from colliding black holes far outside our galaxy opened a new window to understanding the universe. A...
A team led by Austrian experimental physicist Rainer Blatt has succeeded in characterizing the quantum entanglement of two spatially separated atoms by observing their light emission. This fundamental demonstration could lead to the development of highly sensitive optical gradiometers for the precise measurement of the gravitational field or the earth's magnetic field.
The age of quantum technology has long been heralded. Decades of research into the quantum world have led to the development of methods that make it possible...
02.05.2018 | Event News
13.04.2018 | Event News
12.04.2018 | Event News
23.05.2018 | Life Sciences
23.05.2018 | Physics and Astronomy
23.05.2018 | Life Sciences