The Horsehead Nebula

Click on the image to view full size! Image Acquisition Details: 86x 120s Ha + 38x 120s Sii + 10x 120s Oiii subs: total 4.4 hrs.

Equipment:

• William Optics Zenith Star Z73 APO telescope

• Ha, Sii and Oiii Narrowband filters

• ZWO ASI 294 MM Pro Camera @ -10 c

• Skywatcher EQ6-R mount

• Guided using ASIair Pro.

The Horsehead nebula (Barnard 33) and the Flame nebula (IC434) lie in the constellation of Orion right beside the third and lowest star of the three stars of Orions belt, this star is the bright class O star, Alnitak. To give a sense of scale, the dark cloud of the actual 'Horsehead' is 7 light years in diameter making the entire width of this image approx 210 light years across.

Alnitak is a triple star system, with the primary star a hot blue supergiant, this is the brightest Class O star in the night sky. Alnitak is a star estimated to be 33 times more massive than our own sun, is around 21,000 times brighter and lies about 1260 Light years (Ly) from earth.

Alnitak and the sun for size comparison

The horsehead itself (Barnard 33) is a column of dark interstellar dust rising in front of a vast cloud of primarily ionised Hydrogen gas and ionised sulphur. To the left of the image and directly below Alnitak is IC434 - The flame nebula