The Tulip and Cygnus X-1

in Cygnus

The Tulip and Cygnus X-1
Éder Iván
Cygnus X-1 rajz
Cygnus X-1 system drawing. (NASA)
Cygnus X-1 ábra
Cygnus X-1 jet and wavefront
The Tulip Nebula

The most prominient part of the image is the Tulip Nebula, cataloged as Sharpless 101 (Sh2-101). It is a H II region emission nebula lying at a distance of about 6,000 light-years from us. It is called Tulip Nebula because it resembles the outline of a tulip when imaged photographically.

Cygnus X-1

At the right of the Tulip Nebula there is located the brightest X-ray source of the constellation Cygnus, discovered in the middle '60s. It consists of a bright blue star (HDE 226868) and a high mass very small object that orbit around each other in a period of 5,6 days. This object was one of the first candidates for a black hole, but astronomers were unable to determine the hole’s exact nature for a long time. By 2011 they managed to measure its distance with high accuracy, so now the numbers show that the the compact object has a mass of 15 Suns and its diameter is about 50 kms only. That means this is a black hole. The black hole pulls gas off the surface of the star and this gas heats up and shines in X-rays as it falls towards the black hole. At the same time a pair of relativistic jets form as well and they emanate perpendicular to the accretion disk of the black hole. The curved bow shock structure shown in the image is the result of one of these jets interacting with a dense interstellar material.

Image details

300/1200 Newton, 3" Wynne-corrector (1130mm effective focal length)
QSI 683 WSG-8, Ha, OIII, RGB filters
Fornax 51 + Boxdörfer DynoStar
Off axis, Lacerta-MGen autoguider + Mgen2Maxim
Exposure time, filters:
Ha: 270 min, OIII: 420 min, RGB: 30-30-30 min. 13 hours total.
Location, date:
Ágasvár, (Mount Mátra), Hungary; 2015 summer
Observing conditions:
Transparency: 7/10, Seeing: 6/10
ImagesPlus, Registar, Pixinsight LE, Photoshop

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