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M106

(James Clark - 2022)
(James Clark - 2022 + 2023)
(Ivor Trueman)
Cropped close-up (Ivor Trueman)

Information...

M106, which lies in the constellation of Canes Venatici, is an intermediate spiral galaxy (i.e. one where the central region has a slight 'bar' structure, but which isn't as pronounced as you find in a barred spiral).

It lies at approx 22-25 million light-years from Earth and it's bright active nucleus makes the Galaxy a Type II Seyfert, with a supermassive black hole at the centre. Radio wavelength observations indicate that a disk of molecular gas orbits within 1 light-year of the central black hole.

One charactersistic of this galaxy is the amazing Hα jets, which can be seen in James' combined 2022/23 image. This is the result of over 68 hours exposure (40.5 hours Hα + 14 hours luminance & 14 hours RGB). For higher resolution see James' Astrobin page.

For more info. see the Wikipedia entry.

 

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Map

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Measuring Angles

Hold your arm at full length, then close one eye & use the hand shapes shown above to measure the angular distance between the stars.

(Ain't anatomy wonderful!)

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Apparent Magnitude

The apparent magnitude of a star is a measure of how bright it appears from Earth. The scale was introduced over 2,000 years ago by the Greek astronomer Hipparchus, who grouped stars into six categories. The brightest 20 or so were deemed to be 'first magnitude', slightly dimmer stars 'second magnitude', and so on until the barely visible stars were classed as 'sixth magnitude'.

Later it was recognised that our eyesight, once it has been given time to get used to darkness, has a logarithmic response. i.e. a Mag. 1 star is actually 2.512 times brighter than a Mag. 2 star, or 6.310 times brighter than a Mag. 3 star (2.512 x 2.512 = 6.310).

The six Magnitudes thus corresponds to a 2.5126 difference in brightness or 100x.

Apparent magnitude

Today the scale has now been extended, so that brighter objects can have an apparent magnitude of 0 or even negative. The brightest star Sirius, for example, has an apparent magnitude of -1.44 and the Sun is a whopping -26.74, due to it's close proximity to Earth.

 

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