Sunday, August 18, 2013

Eleven hours with Little Fox

Vulpecula is latin name for Little Fox constellation. It is little and contains no bright stars. It is placed nearby Swan constellation in the pretty bright region of Milky Way. Well known M27 Dumbbell planetary nebula is in the Little Fox constellation (http://astrojolo.blogspot.com/2012/08/wakacyjne-owy.html) and actually not much more. But if you look there and stay for over eleven hours you may notice some very faint nebulosities. Of course not look with an eye, but telescope with connected camera instead. 


In the center of the picture there is NGC6823 star open cluster. It is placed about 6000 light years away. If you point your there telescope, even large, you will notice a bunch of young, blue stars and nothing more. These stars are about two million years old, so they are pretty young. The faint, surrounding nebula is called NGC6820 (or Sharpless 86) and is typical hydrogen emission nebula (hence its red color). It contains several dark globules. And that is pretty much all about it, no bells and whistles.
Oh...
Below the picture center and little to the right there is a tiny emission cometary nebula denominated GN 19.40.3 (aka GM1-26). When you enlarge the picture you will spot small comet like shape - but it is not a comet at all.
Oh...
The total exposure time was 11 hours - it is my new personal record. Picture has been exposed during three nights. I practice my patience :) Setup as usual - GSO 6" F5 newtonian with 0.9x field flattener and modded Canon 450D at ISO800. 5 minutes subexposures.

Clear skies!

Friday, August 16, 2013

Bubble friends

In the border of Cepheus and Cassiopeia constellations some interesting objects can be found. The most famous is probably Bubble Nebula (NGC7635 aka Sharpless 162 aka Caldwell 11). One may try to recognize it by himself at the picture below and really should not fail :)
It is HII region emission nebula. The bubble shape is created by the stellar wind from a massive hot young central star that is thought to have a mass of 10-40 Solar masses (can be seen in the upper left part of the 'bubble'). The bubble expansion is beeing suppressed by external molecular cloud. Nebula is placed about 11,000 light years away and has been discovered by William Herschel in 1787 year.
In the right part of the picture you will find NGC7538 nebula. This one is located 9,100 light years away from Earth. It is home to the biggest yet discovered protostar which is about 300 times the size of our Solar System. The nebula is a region of active star formation.
To the left there is easly recognized Messier 52 open star cluster. It is evaluated at about 35 million years old cluster that contains about 190 identified members. Can be spotted with binoculars. 
Below M52 you can see 3 bright stars, and just behind it there is Czernik 43 open cluster. It is much more scattered than M52 and contains 30-40 stars.
The middle and left picture part seem to be a little bit reddish because all this region contains hydrogen clouds that are excited by nearby stars and radiates in red color (hydrogen line 656nm). It is a perfect region for narrowband astrophotography, but DSLR can also do some job here :)
Pictured with usual current setup: GSO 6" F5 newtonian with FF 0.9x and modded Canon 450D. ISO800, subexposure time 5 minutes, total 6.5h.


Clear skies!

Wednesday, August 14, 2013

Floating in the hydrogen sea

As already mentioned in the previous entry Swan nebulaes strikes back most nebulas are emission or reflection. Large, red hydrogen clouds are the most common emission nebulas. Reflection ones reflects the light of nearby stars, so they can be of different colors. Sometimes in the star neighbourhood there are both hydrogen and dust clouds and we can spot both nebula types in the same sky area. This scenario is presented in the picture below.

In the constellation of Cygnus nearby IC1318A nebula there is object called NGC6914. It blue reflection nebula placed about 6000 light years away. It is just a dust cloud illuminated by collection of young, blue stars, most of which are hidden by surrounding dust. The same dust cloud veils the red emission nebulaes behind and can be spotted as dark clouds. The illuminating stars of the nebula belong to Cygnus OB2 association. It contains about 2600 huge stars spread across 200 light years of space. Most of them are obscured by Milky Way dust clouds in that area known as a Great Rift.
Next picture shows enlarged central fragment of the previous one. Both parts of nebula are identified there and also so called "Boomerang star". Catalog name of this peculiar star is V1515 Cygni and belongs to the FU Orionis family of variable stars. This star display an extreme changes in both magnitude and spectral type. "Boomerang" comes from the small nebula shape that is barely visible in my picture - this nebula can be subject for much larger instruments.
Picture itself has been exposed during three different nights with total exposure time of 8 hours. Setup is as usual these days - GSO 6" newtonian with field flattener and effective focal ratio of f/4.5. Detector is modded Canon 450D working at ISO800. Subexposure time was 5 minutes. Setup guided with short tube guider and QHY5 camera. Postprocessing using Maxim and PS CS2.

Clear skies!

Monday, August 12, 2013

Swan nebulaes strikes back

Cygnus (The Swan) constellation is filled with hydrogen clouds that are ionized and radiate massively in red light (656nm that is hydrogen alpha line). Some time ago I shot the IC1318 Butterfly Nebula (http://astrojolo.blogspot.com/2012/09/jesienne-abedzie-spiewy.html) but in fact it was only a part of it (actually parts B and C). Now part A is going to be presented. The whole IC1318 nebula complex is about 3700 light years away from us. Most of nebulas can be described as emission or reflection ones. Reflection nebula is a dust cloud. If there is a star nearby it reflects star light. If there is no star - the dust cloud may be detected as opaque clouds blocking light from objects behind them.
Emission nebula on the other hand emits spectral light radiation from ionized gas. In case of IC1318 it is ionized hydrogen. Young blue stars in this nebulas emits large amount of UV light that ionize the surrounding gas. This giant, red hydrogen nebulas are called HII regions


The picture above has been exposed over two August nights. The total exposure time was 7.5 hours using Canon 450D camera modded for red light. GSO 6" F/5 newton telescope was equipped with 0.9x field flattener and worked with effective focal rafio of f/4.5. In spite of such long exposition the amount of detected red light is not remarkable, because in DSLR cameras only one out of four pixels detects red light.

Clear skies!