I'm about 7 weeks into a distance learning MSc in astrophysics with LJMU. Over the past two weeks the topic being covered was the interstellar medium (ISM) - the vast regions filled with gas and dust between the stars throughout the Milky Way.
During this time the weather has been mostly awful! But there have been a couple of clear nights and during those I've finally been able to try a modified DSLR on loan from a friend to get some images nebulae that are beyond the reach of my normal DSLR.
Here are two pictures taken by stacking dozens of images together. Both were captured through an 80mm refractor.
These nebulae are created when radiation from a hot, young star ionises neutral hydrogen nearby. When the electrons recombine with the hydrogen a very particular photon (corresponding to red light) is emitted. If the star was surrounded by a uniformly dense hydrogen cloud then the resulting nebula would be spherical, with the boundary of the nebula being the place where ionisations and recombinations balance. That's nearly the case for NGC280 above! But hydrogen clouds aren't necessarily distributed so perfectly around stars. In the picture of NGC1499 the nebula is created by the bright star near the bottom of the picture. The hydrogen cloud is clearly some distance from the star.
Hydrogen exists in several forms throughout the Milky Way. Clouds of hydrogen atoms are called HI (H-one!) regions. These ionised nebulae are called HII regions (not to be confused with H2 regions of molecular hydrogen).
I always enjoy getting pictures of these fantastic objects but the astrophysics course is adding a new layer of appreciation to what I'm doing.
Comet 2013 US10 Catalina will appear in the morning sky for UK observers from the end of November. It looks like it will become a binocular object at least; fingers crossed that it becomes brighter still!
Here's a finderchart showing the trajectory of the comet during December and early January.
Comet Catalina is tracking north very rapidly. During December it moves from Virgo into Bootes. On the first day of 2016 the comet will pass within 1 degree of Arcturus - the brightest star in the northern hemisphere of the sky. The contrasting colours of orange Arcturus and the dusty comet (perhaps with a green coma) should make an excellent photo!
Comet Catalina reaches perihelion (closest point to the Sun) on November 15th. The comet will be 0.82 AU (123 million km) from the Sun; between the orbits of Venus and Earth. Catalina won't be visible from the UK until it has moved further north, away from the Sun's glare towards the end of the month. Comet Catalina will be closest to Earth on January 17th 2016, at a distance of 0.72 AU (108 million km).
Comet Catalina was discovered by the Catalina Sky Survey in 2013. It is a dynamically new comet; it was perturbed from the Oort Cloud several million years ago and the trajectory after perihelion shows it will likely be ejected from the solar system - never to return.
Catalina is predicted to fade slightly after perihelion with brightness estimates putting it between 5th and 6th magnitudes. Dark skies away from light pollution should allow anyone with binoculars and telescopes to view the comet.
Dr Adrian Jannetta
Guitar strummin' explorer of the universe. Mild mannered maths teacher by day and astronomer by night.