GALAXYPHOTO

Astrophotography by Michael Deger

Astrophotos

NEW ASTROPHOTOS

LBN 331

10″ Lacerta Newton

IC 5070

10″ Lacerta Newton

NGC 7822

4.5″ Newton

NGC 4725 + PN LoTr 5

4.5″ Newton

On this webpage you will find astronomical images of our universe, mainly showing Deep-Sky-Objects like Galaxies, Nebulae and Star Clusters.These images were taken at Erdweg/Germany under a light polluted sky with some disturbing lights, using different telescopes and cameras. Some objects are so far away that their light have been travelling thousands or even millions of years to reach us. So we can never see the universe as it is, a deep look into space shows always the objects as they existed a lot of years ago.

If you look through a telescope, most of the faint objects appear just in gray without color. The emitted light is too dim, our eyes can only pick up the light at that very moment. A CCD camera converts light into electrical signals which can be integrated during several minutes. So it is extremely photosensitive and enables an object to be displayed in color with the help of at least three different colour filters (red, green and blue). Long exposure times are the essential precondition to produce an image with good colors and lots of details. For the most of my Deep-Sky-Images light has been captured over many hours with a modern CCD camera.

My current setup consists of a 10″ Lacerta Newton and a 4.5″ Newton, carried by a 10Micron GM1000 HPS mount. For image acquisition I use a monochrome SBIG ST8300M CCD camera with Baader filters. Thank you for stopping by. New images are added from time to time, so feel free to visit again. I hope that you enjoy your visit on my website and that you can find some nice images and useful information.

A look into the depths of the universe

Some questions about astronomy

A light year is the distance that light travels in a vacuum within one year. The speed of light c is 299,792.458 km/s. This means that light in a vacuum covers a distance of 9.4605 trillion km per year.

Some distances (light travel times):

Earth-Moon: 1.3s

Earth-Sun: 8min 20s

Earth – Proxima Centauri (nearest star): 4.3 Ly

Earth – Center of our Milky Way: 26000 Ly

Earth – Andromeda Galaxy (Neighbor galaxy): 2.2 Mio Ly

Earth – Virgo Cluster: 60 Mio Ly

Earth – Stephan’s Quintet: 300 Mio Ly

Comets are celestial bodies in our solar system that are up to 30 km in size and consist mainly of rock, dust, ice and frozen gases. Comets are located in the outer solar system in the Oort cloud outside the planets at a distance of up to one light year. Most comets have elliptical solar orbits. As soon as they come close to the sun, their speed increases sharply. The solar radiation causes gases on the surface of the comet to vaporize and form a coma around the comet’s nucleus. The tail of a comet, which can be up to several million kilometers long, is created by the solar wind and shines brightly in the reflecting sunlight. The dust tail appears along the comet’s orbit, while the gas tail points away from the sun.

Nebulae are clouds of dust and gas (interstellar matter) within a galaxy that are excited to glow or reflect light. Many new stars are formed in these huge gas clouds. Over 90% of nebulae consist of hydrogen and helium.

There are different types of nebulae:

– Emission nebulae: Emission nebulae are interstellar clouds of dust and gas that emit their own light in different colors. Many emission nebulae glow in red (Hα line in HII regions)

– Reflection nebulae: Reflection nebulae are dust clouds that reflect the radiation of the surrounding stars. The stars in reflection nebulae are not hot enough to cause the nebula to glow. However, the light is scattered by the nebula molecules, making the nebula visible. The typical color for reflection nebulae is blue, because the scattering is stronger for blue light than for red.

– Dark nebulae: Dark nebulae are large clouds of interstellar matter that absorb the light of objects behind them. Parts of emission or reflection nebulae are obscured or background stars are darkened or faded out.

– Planetary nebulae: A planetary nebula consists of a shell of ionized gas that was ejected from an old star at the end of its evolution. Many planetary nebulae shine in the [OIII] line, which is why they show a bluish green color.

A galaxy is a gravitationally bound, massive system of stars, gas nebulae, dust clouds, planetary systems and dark matter. There is a great variety of galaxies, from small dwarf galaxies with around 10 million stars to giant galaxies with up to 1 trillion stars.

-Spiral galaxies: Spiral galaxies are disk-shaped galaxies. The disk, consisting of stars, dust and gas, shows a spiral structure with several spiral arms. The central area of these galaxies (bulge) consists mainly of older stars.

– Elliptical galaxies: Elliptical galaxies are probably formed by the merging of spiral galaxies. They consist mainly of older, massive stars. These galaxies are surrounded by a large number of globular clusters.

– Irregular galaxies: Irregular galaxies are uneven galaxies that have neither a spiral nor an elliptical structure.

Star clusters are large star systems that are gravitationally bound together.

– Globular clusters: A globular cluster is a star cluster consisting of a large number of very old stars. The star density shows a spherically symmetrical distribution that decreases evenly in all directions from the center to the edge.

– Open star clusters: Open star clusters usually consist of less than a few hundred stars. Open star clusters are young stars, they are only a few hundred million years old or younger.

Stars differ not only in their brightness, but also in their colors. Some shine more in white light, others red or blue. The color of a star is determined by its surface temperature. The colors show the different types of stars (spectral types), which differ from each other by their temperature. Very hot stars shine blue, while very cool stars shine red. 

The different spectral classes of stars are designated by the letters O, B, A, F, G, K, M.

The hottest violet stars are the central stars of planetary nebulae with surface temperatures between 100,000 K and 50,000 K (type W).

Star colors:

Violet: 100.000 K to 50.000 K (type W)
Blue: 60.000 – 30.000 K (type O)
Blue-white: 30.000 – 10.000 K (type B)
White: 10.000 – 7.500 K (type A)
Yellow-white: 7.500 – 6.000 K (type F)
Yellow: 6.000 – 5.000 K (type G)
Yellow-orange: 5.000 – 3.500 K (type K)
Red: < 3.500 K (type M)

These classes are further subdivided into ten subclasses from 0 to 9 for finer differentiation, with 0 being the hottest and 9 the coolest. An F9 star is therefore hotter than a G0 star. Incidentally, our sun is a G2 star – a relatively hotter of the yellow shining stars.

The magnitude, or apparent brightness, indicates how bright a star or other celestial body appears to an observer on Earth in comparison. The lower this value is, the greater the apparent brightness of the object. Stars are divided into six magnitude classes. The brightest stars, such as Antares in Scorpius or Regulus in the constellation Leo, were defined as first magnitude stars. Visible stars that are just visible to the naked eye form the sixth magnitude class and therefore the lower end of the scale.

The scale is not linear; the brightness changes by a factor of 2.512 from one magnitude class to the next. This means that a star in the 1st magnitude class is 100 times brighter than a star in the 6th magnitude class (2.512 x 2.512 x 2.512 x 2.512 x 2.512 = 2.512⁵ = 100.023). Very bright objects have a negative magnitude.

Examples of apparent brightness:

Sun: -26,7 mag

Full moon: -12,5 mag

Venus (at maximum brightness): -4,4 mag

Jupiter (at maximum brightness): -2,9 mag

Sirius: – 1,5 mag

Wega: 0,0 mag

Pole star: 2,0 mag: 2,0 mag

Andromeda Galaxy: 3,4 mag: 3,4 mag

Orion Nebula: 3,7 mag

Limit naked eye under optimal conditions: 6,0 mag

Limit Binoculars (7×50): 9,0 mag

Visual boundary brightness telescope (10″): 14,1 mag

Limit Hubble Space Telescope: 28,0 mag

The Bortle scale indicates the extent of light pollution at an astronomical observation site. The scale ranges from class 1, the darkest sky on earth, to class 9, the inner-city sky.

Class 1: Excellent location (e.g. desert), extremely dark – limiting magnitude 8.0 to 7.6 mag

Class 2: Very good location (e.g. high mountains), very dark – limiting magnitude 7.5 to 7.1 mag

Class 3: Good location (e.g. rural regions), dark – limiting magnitude 7.0 to 6.6 mag

Class 4: Transition between country and suburb – border size 6.5 to 6.1 mag

Class 5: Suburban – limiting magnitude 6.0 to 5.6 mag

Class 6: Bright suburb – limiting magnitude 5.5 to 5.1 mag

Class 7: Transition between suburb and city – border size 5.0 to 4.6 mag

Class 8: City – limiting magnitude 4.5 to 4.1 mag

Class 9: City center – limiting magnitude 4.0 mag and brighter

“Two things are infinite: the universe and human stupidity. And I’m not sure about the universe.”

Albert Einstein

LG