M51 - NGC5194 - Whirlpool Galaxy  
Canes Venatici

Interacting grand-design spiral galaxy, one of the most famous spiral galaxies in the sky. 		 
 
It is located at a distance of approximately 23 million light-years in the constellation Canes Venatici. The galaxy and its companion (NGC 5195) are easily observed by amateur astronomers, and the two galaxies may even be seen with binoculars.

he Whirlpool Galaxy was discovered by Charles Messier on October 13, 1773. Its companion galaxy, NGC 5195, was discovered in 1781 by Pierre Méchain. It was however not until 1845 that the Whirlpool became the first galaxy to be recognized as a spiral. This was achieved by Lord Rosse employing a 72-inch reflecting telescope which he constructed at Birr Castle, Ireland. In 2005 a supernova (SN 2005cs) was observed in the Whirlpool Galaxy, peaking at apparent magnitude 14. Sometimes M51 is used to refer to the pair of galaxies, in which case the individual galaxies may be referred to as M51A (NGC 5194) and M51B (NGC 5195).

With derived estimate of 23 Mly distance, and an angular diameter of roughly 11.2′, we can infer that M51's bright circular disk has a radius of about ~38 kly. Its mass is estimated to be 160 billion solar masses. Compared to 100 kly diameter of the Milky Way, M51 has about half its size and mass.

Decades ago, it wasn't known for certain if the companion galaxy NGC 5195 was actually a true companion or rather some other galaxy passing at a distance. The advent of radio astronomy and subsequent radio images of M51 unequivocally demonstrated the reality of the interaction.

Recent simulations bear out that M51's spiral structure was caused by NGC 5195 passing through the main disk of M51 about 500 to 600 million years ago. In this model, NGC 5195 came from behind M51 through the disk towards the observer and made another disk crossing as recently
as 50 to 100 Myrs ago until it is where we observe it to be now, slightly behind M51.

A black hole surrounded by a ring of dust exists at the heart of the spiral. The dust ring stands almost perpendicular to the relatively flat spiral galaxy. A secondary ring crosses the primary ring on a different axis, a phenomenon that is contrary to expectations. A pair of ionization cones extend from the axis of the main dust ring.
 
 
Technical details:  
Location:  
 Valdemorillo - Spain
Date:  
 21/01/2011 (dd/mm/yyyy)
Conditions:  
 Good
Temperature:  
 -5ºC
Humidity:  
 low
 
Telescope:  
 GSO Reflector 200mm f/4
Reducer/corrector:  
 Baader MPCC
Filter:  
 IDAS LPS 2"
Mount:  
 Orion Atlas EQG
Camera:  
 Atik 314L+
Exposure:  
 124 x 30s, T=-5ºC
Guiding tube:  
 B&C 60/350 f7
Guiding camera:  
 Meade DSI Pro
Guiding software:  
 PHD Guiding
 
Procesing:  
 Calibrated, registered and integrated with PixInsight Core.
Processing with PixInsight Core.		  
Notes:  
 First light Atik 314L+.
No dark. Flats and bias used, but still no good flats tehnique learned for Atik314L.
Very noisly for 127 shots, may be due to such small subexposure time (30s).
--
29/ene: Perdidos los FIT originales.
 
     

 
All Contents Copyright by Jaime Fernández and Copyright of their respectives owners. Text mainly extracted from Wikipedia.
All Jaime Fernandez propietary contents freely available for non-profit purposes,
otherwise I beg you for a fair contribution to NGO Medicos Sin Fronteras proportional to the profit obtained.

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