The Pleiades (M45)

The Pleiades (M45)

The Pleiades (also known as the Seven Sisters and Messier 45). This is one of my favourite autumn targets and one I feel compelled to image every year in order to try and improve on previous attempts. Their rising heralds the arrival of the constellation of Orion which pursues them. I love the mythology associated with the Pleiades and Orion and different cultures have their own stories to explain them. M45 always seems like it should be a fairly easy object to image and it is, however processing it is another matter. This image was made over two nights (24/09/18 and 03/10/18). The original idea was to capture all the data in one night but the first night, although being very clear, was a full Moon and many of the subs were washed out making processing a nightmare. The second night the Moon wasn’t an issue but conditions were still less than ideal and we were shooting into a murky sky with high cloud. Ultimately I combined the best shots from both nights and this is the result…by no means perfect but as good as I can get it, not too noisy and a reasonable amount of nebulosity coming through.

The Pleiades are an open star cluster containing middle-aged, hot B-type stars located in the constellation of Taurus. It is among the nearest star clusters to Earth and is the cluster most obvious to the naked eye in the night sky.

The cluster is dominated by hot blue and luminous stars that have formed within the last 100 million years. A faint reflection nebulosity around the brightest stars was thought at first to be left over from the formation of the cluster (hence the alternative name Maia Nebula after the star Maia), but is now likely an unrelated foreground dust cloud in the interstellar medium, through which the stars are currently passing.

Computer simulations have shown that the Pleiades were probably formed from a compact configuration that resembled the Orion Nebula. Astronomers estimate that the cluster will survive for about another 250 million years, after which it will disperse due to gravitational interactions with its galactic neighborhood.

Information courtesy of Wikipedia:
en.wikipedia.org/wiki/Pleiades
en.wikipedia.org/wiki/Pleiades_(Greek_mythology)

060 x 300 second exposures at Unity Gain (139) cooled to -20°C
030 x dark frames
063 x flat frames
100 x bias/offset frames
Binning 1×1

Total integration time = 5 hours

Captured with APT
Guided with PHD2
Polar Alignment with SharpCap Pro
Processed in Nebulosity, Fitsworks, Microsoft ICE and Photoshop

Equipment
Telescope: Sky-Watcher Explorer-150PDS
Mount: Skywatcher EQ5
Guide Scope: Orion 50mm Mini
Guiding Camera: ZWO ASI120MC
Imaging Camera: ZWO ASI1600MC Pro
Baader Mark-III MPCC Coma Corrector
Light pollution filter

Posted by Davide Simonetti on 2018-10-07 11:51:56

Tagged: , Pleiades , Seven Sisters , Messier 45 , Star Clusters , Stars , M45 , Maia , Electra , Taygete , Alcyone , Celaeno , Sterope , Merope , Pleione , Atlas , Astrophotography , Astronomy , Space

Tarantula nebula in the LMC

Tarantula nebula in the LMC

I have not generally been posting astronomical images on flickr since almost all of them are widely available on other websites. However, I have decided now to post a few which have some special interest or connection with other things that I do.

Number one has to be the Tarantula nebula photographed with the Wide Field Imager on the ESO/MPG 2.2m telescope on La Silla in Chile. The reason I choose this is that it is a spectacular image that took a lot of effort to create. It is also the first astronomical image that I processed using ‘tonemapping’ as applied to multi-exposure High Dynamic Range terrestrial images. The work was done in collaboration with Joao Alves, Benoit Vandame and Yuri Beletski with Benoit doing a great deal of hard work preparing the original filter images in this 2×2 field mosaic (which would encompass 2×2 full Moons) ready for me to combine into a 4-colour image. This combination resulted in an enormous image which, at the time it was done, stretched the capabilities of desktop computers – and took about a week to do!

The image contains a huge range of brightness that needed HDR techniques in order to enable display on a print or a computer screen. This extends from the centre of the stellar cluster in 30 Doradus to the wreaths of dark dust obscuration surrounding the individual nebulae.

Although there are many images of this region taken with different telescopes, including Hubble, this image has somehow become iconic. It has been featured by Apple in the "Inside the Image" series:

www.apple.com/science/insidetheimage/fosbury/

and the full-resolution data can be obtained from ESO at:

www.eso.org/public/images/eso0650a/

This region in the Large Magellanic Cloud (about 170,000 light years away) is a huge stellar nursery containing infants (bright green nebulae) to mature teenagers (blue stellar clusters). It also contains the remnant of supernova 1987a – the brightest supernova in several centuries (which I was lucky enough to see with the naked eye when observing on La Silla). This is a real challenge to find and is best seen on the full-resolution image from ESO – although it can be seen on the ‘original’ image here on flickr.

The four filters used to capture the colour information were the usual broad-band B (blue) and V (visible/green) as well as narrow band filters that isolated the green light of glowing oxygen (minus 2 electrons; we call it O^2+ or the [OIII] nebular lines at 496 and 501nm) gas and the red light of hydrogen (Hydrogen-alpha or the first line in the Balmer series: level 3 to 2). The nebulae that are green generally contain hotter, younger stars than the red nebulae.

If I were to choose one other image of this region to look at, it would have to be the wonderful UV-NIR image taken with the new Wide Field Camera 3 (WFC3) on Hubble:

www.spacetelescope.org/images/opo0932a/

which shows the central R136 cluster in exquisite detail.

Posted by The^Bob on 2012-08-01 07:11:05

Tagged: , astronomy , image , eso , mpg , 2.2m , wfi , b , v , ha , oiii , vandame , alves , beletski , hdr , tonemapped , mosaic , sn1987a , honeycomb , star-clusters , stars , nursery

The Pleiades (M45)

The Pleiades (M45)

The Pleiades, or Seven Sisters (Messier 45 or M45), is an open star cluster approximately 444 light years away from Earth containing middle-aged hot B-type stars located in the constellation of Taurus. It is among the nearest star clusters to Earth and is the cluster most obvious to the naked eye in the night sky.

The cluster is dominated by hot blue and extremely luminous stars that have formed within the last 100 million years. Dust that forms a faint reflection nebulosity around the brightest stars was thought at first to be left over from the formation of the cluster (hence the alternative name Maia Nebula after the star Maia), but is now known to be an unrelated dust cloud in the interstellar medium, through which the stars are currently passing. Computer simulations have shown that the Pleiades was probably formed from a compact configuration that resembled the Orion Nebula. Astronomers estimate that the cluster will survive for about another 250 million years, after which it will disperse due to gravitational interactions with its galactic neighborhood.

The name of the Pleiades comes from Ancient Greek. It probably derives from plein because of the cluster’s importance in delimiting the sailing season in the Mediterranean Sea: ‘the season of navigation began with their heliacal rising’. However, the name was later mythologised as the name of seven divine sisters, whose name was imagined to derive from that of their mother Pleione, effectively meaning ‘daughters of Pleione’. However, in reality the name of the star-cluster almost certainly came first, and Pleione was invented to explain it. [Wikipedia]

8 x 2 minute exposures at 800 ISO
11 x dark frames
11 x flat frames
24 x bias/offset frames

Equipment
Celestron NexStar 127 SLT
GoTo AltAz mount with homemade wedge
Orion 50mm Mini Guide Scope
ZWO ASI120 MC imagaing and guiding camera
Canon 700D DSLR (piggybacked on scope)
Tamron 70-30mm lens at 300mm

Guided with PHD
Stacked and calibrated in Maxim DL
Post processed in Maxim DL, Nebulosity, and Photoshop

Posted by Davide Simonetti on 2015-08-22 09:23:34

Tagged: , Pleiades , Seven Sisters , Messier 45 , M45 , Star Clusters , Stars , Astrophotography , Astronomy