Just in from a short imaging session in the back garden. This a picture of the star cluster M41 in Canis Major --- just to the south of Sirius, the brightest star in the night sky.
M41 is one of the brighter star clusters in the night sky, shining at magnitude +5.0 and its 100 or so stars are scattered over an area larger than the full moon.
Viewed from the UK the cluster is at best about 15 degrees above the southern horizon. From my home in Northumberland I'm always viewing this part of the sky through severe light pollution created by Newcastle, Cramlington, Blyth, Ashington and nearby village lights.
The pictures below show what I have to contend with and how I deal with it.
The picture on the left is one of the raw images and it's almost washed out with the pinkish contribution from streetlight pollution. The picture on the left is a "map" of the background created with free software called IRIS. Basically the second picture gets subtracted from the first to leave something looking a lot healthier that eventually ends up as the picture at the top of the page. I described the exact process in an earlier article and it's absolutely crucial to obtaining deep sky images from light polluted skies.
Twelve million years ago, give or take, a star exploded in nearby galaxy M82. Light from this event is arriving at Earth right now. Astronomers given this supernova the official designation SN 2014J.
Here's a picture I took with the 8 inch telescope last night. The supernova is indicated by the red lines.
This supernova has been classified as type 1a - a white-dwarf detonation. The precise mechanism is not well understood. It might be that the white dwarf star - probably about the size of the Earth but and with a mass comparable to the Sun - was drawing material from a companion star onto it and a runaway nuclear chain reaction led to the complete destruction. Or maybe two white dwarfs collided. Whatever the case the tiny, tiny star was obliterated in one of the biggest bangs in the universe.
M82 is a reasonably bright galaxy and I took an image of it last Autumn. Now I have before and after images of a supernova:
M82 is fairly bright galaxy in the night sky and quite easy to find even without a GoTo telescope. M82 is not far from the familiar seven star pattern of The Plough - and always visible from the UK. The galaxy is best viewed later in the evening when it is almost overhead in the UK.
SN 2014J will continue to increase in brightness in the coming days. The luminosity increase is not instantaneous. Radioactive Nickel-56 is produced during the supernova and when it decays it excites the surrounding gas to incandescence. The half-life of 6 days means that peak brightness occurs well after the supernova first happens.
The bright star pattern of Orion is a great place to begin navigating the sky at this time of the year. Orion is easy enough to find; face south and look for three bright stars a straight line. Those stars mark Orion's Belt and is the centre of the constellation.
If you can find the stars of Orion then you can use the shape to find other interesting stuff in the sky. For example, you can hop from the three Belt stars to a few other things.
Follow the line from the stars down towards the horizon and you spot the brilliantly twinkling star called Sirius. This is actually the brightest star in the sky (and one the nearest to us). Sirius is a bit more massive than the Sun and this translates to it putting out more that 25 times as much energy as the Sun does. It is only outshone in the night sky by the planets Venus, Jupiter and occasionally Mars. From the UK it never gets particularly high in the sky and so its light has to pass through the atmosphere at a shallow angle. This causes it to twinkle violently and flash different colours of the rainbow. This can make for some interesting pictures!
The early evening night sky in January looks something like this in the Uk.
Stars and constellations
The southern part of the sky is dominated by the bright stars of the constellation Orion.
This striking star pattern lies on the celestial equator and is visible from all inhabited places on Earth. Orion in mythology was a great hunter and it doesn't take much imagination to visualise a human figure holding a shield (or a bow). Big broad, shoulders but a few faint stars marking the head (showing that he is more brawn and not much brain, according to Eva Hans, formerly of South Tyneside College Planetarium!)
The brightest stars in the constellation are Betelgeuse (with a definite orange/red hue) marking the right shoulder and Rigel (white/blue colour) marking a knee. In star atlases Betelgeuse is labelled "alpha" and Rigel is "beta". However, Rigel is usually the brighter of the two, with Betelgeuse occasionally fluctuating enough to surpass it in brilliance. Betelgeuse is a big star near the end of it's life and good candidate for becoming one our galaxy's next supernovae.
Beneath the Belt stars is a compact group of stars known as Orion's Sword. Binoculars show this region has a large fuzzy region, which telescopes reveal to be a bright nebula --- the Orion Nebula. The other stars of the Sword are revealed to be star clusters rather than individual stars.
The whole region is superb to see with telescopes of any size.
The three prominent Belt stars, which make an almost perfect straight line, point upwards towards Taurus and the orange star Aldebaran, marking the eye of the Bull. Follow the line of the Belt stars down towards the horizon and you'll see the madly twinkling Sirius - the brightest star in the sky.
Above Orion the planet Jupiter is at its most brilliant. The planet is at opposition (meaning opposite to the Sun in the sky) this month. This month, not only is Jupiter at its closest to Earth of the year it is also at the best place in the 12 year long orbit for observing in the UK.
The Milky Way runs from northwest to southeast in the sky. Although this section of the Milky Way is less prominent than the part visible in the late summer and autumn in the UK, there are numerous star clusters and nebulae visible with binoculars and small telescopes as it flows through Auriga, Gemini and to the east of Orion and on to Canis Major in the south.
By contrast, the western part of the evening sky is fairly devoid of the bright stars. The autumn patterns of the Square of Pegasus, Pisces and Cetus mark a direction in which we can look out of the plane of the Milky Way, where there are fewer stars in that direction between us and the great voids between other galaxies.
In the east, particularly later in the evening, the galaxy filled constellations of Leo and Virgo are coming into view. More about those next month!
The moon and hours of darkness
The best evening opportunities to have moonless sessions of astronomy come in the first week, before first quarter moon and then from January 19th until the end of the month.
Mercury will be visible in the evening sky in latter half of January. The picture shows the view towards the western horizon at about 5.30pm at the end of January. Mercury will be shining a full magnitude brighter than Vega (over the northwest horizon). Mercury reaches a maximum elongation of 18 degrees east of the Sun on January 31st and should be visible easily for a week either side of this date.
Venus is quickly slipping between the Earth and Sun and will be visible in the evening sky shortly after sunset during the first few days of January. Venus is at inferior conjunction on January 11th and emerges in the morning sky before sunrise later in the month.
Mars and Saturn are best seen in the morning sky. The picture shows the view towards the southeast in the middle of the month at about 4.30am. Mars is among the stars of Virgo near the bright star Spica. The colour of orange/red Mars and bluish Spica will contrast nicely as both are about the same brightness. Saturn is in the constellation Libra and closer to the horizon. Saturn is shining as brightly as Mars and Spica but with a more yellowish/cream colour.
The planet Jupiter reaches opposition in January and is observable all night. Jupiter is in the constellation Gemini and is the brightest "star" in the sky after sunset. Visible in the east during the early evening Jupiter climbs high into the southern sky by the middle of the night. Binoculars, steadily held, will reveal up to four of its moons and a view similar to that seen by Galileo when be discovered them. Telescopes will show the two equatorial belts of dark cloud on the planet, while larger instruments will reveal the some of the larger Jovian storms such as the Great Red Spot.
The rotation period of Jupiter is just under 10 hours so the long winter nights in the UK make it possible to watch the entire planet rotate between dusk and dawn.
Quadrantid Meteor Shower
The annual Quadrantid meteor shower is active between December 28th and January 12th. The peak in 2014 comes on the evening of January 3rd, with the best time to observe being the early hours of January 4th. During the narrow peak rates as high as 120 meteors per hour might be possible.
The Quadrantid meteors radiate away from the border of the constellations Bootes and Hercules and it is named after a now defunct constellation – Quadrans Muralis - the Mural Quadrant.
The crescent moon will have set long before the radiant is high in the sky. More details to follow in a post nearer the time.
Comet 2013 R1 Lovejoy
The brightest comet in the sky at present is Comet 2013 R1 Lovejoy.
Comet Lovejoy peaked in brightness (mag +4.5) in early December and was a naked eye object from dark observing sites. The comet continued to approach the Sun during December and reached perihelion on the 22nd (0.8AU from the Sun).
Comet Lovejoy is best seen in the hours before sunrise in the UK. It remains bright enough to be seen with binoculars and small telescopes but is now fading. Telescopes with apertures of 4 inches or more will show the tail easily. Images of the comet taken in mid-December showed a tail stretching across 20 degrees of the sky!
Although Comet Lovejoy is fading and moving towards the southern hemisphere of the sky, it will remain observable in the UK for the rest of January. The following star chart shows the movement of Lovejoy during the month.
The comet begins the month in the southern part of Hercules at around 5th magnitude. It is expected to fade to 7th magnitude by the end of the month.
A new star has appeared in the sky. Well, not really. It was there all along but it suddenly flared in brightness and caught the attention of an astronomer on August 14th. Astronomers call it Nova Delphini 2013.
A nova is a stellar outburst but on a less violent scale than a supernova. Unlike a supernova, a nova does not destroy the star.
Novae occur in binary systems where one of the pair of stars is a hot, compact object called a white-dwarf. The other star in the system (maybe a main sequence or red giant star) orbits close enough for material to drawn into an accretion disk around the white dwarf. The material (hydrogen and helium mostly) adds mass to the surface of the white dwarf and increases the temperature and pressure until a runaway nuclear reaction begins. Some of the energy released is in the form of light (the nova in this case brightened by 25,000 times than the progenitor binary system) and intense stellar winds - strong enough to blow away the deposited material so that the reaction eventually grinds to a halt. The flare in brightness is followed by a decay to normality.
The nature of the binary system means that the process may repeat after intervals of decades, centuries or many millennia.
Novae can recur if we wait long enough.
Finding the nova
The nova has the following coordinates:
Right Ascension 20h 23m 30.1s
Declination: +20° 46' 04"
That puts it in a very convenient part of the sky for UK astronomers at this time of the year. Here's a star chart showing the location of the nova in relation to bright stars of the Summer Triangle.
The nova is within the borders of Delphinus (hence the name Nova Delphini 2013) and the borders of Vulpecula and Sagitta. It's probably easiest to locate it visually using Sagitta as a starting point.
I put a couple of green arrows on to show how to star-hop to it from the relatively easy-to-see shape of Sagitta. Follow the shaft of the arrow - it almost points straight to the nova. in binoculars, there are only a couple of stars nearby to rival the nova in brightness.
The nova was about 6th magnitude when it was discovered. That means it was barely visible to the naked eye from darksky site. In a few days it had doubled in brightness and is currently shining at 5th magnitude. That makes it one of the brightest novae of recent years and an easy target for binoculars and small telescopes.
This is the best time of the year to appreciate the crowded starfields of the Milky Way. Until last week Nova Del 2013 was white dwarf lost among the countless millions of stars beyond the reach of all but the biggest amateur telescopes. For now it stands out from the crowd.
Sat in the garden with a cup of coffee watching the Perseids zip across the sky. I saw a couple of dozen - it averaged out at about one per minute. The camera was taking one minute exposures of the whole sky. The best picture I got showed a Perseid shooting down the Milky Way as it emerged from behind a cloud.
The shower is building towards a maximum this evening and forecast is good. I'd like to get another meteor picture without a pesky cloud in the way.
I was torn between leaving the camera taking whole sky pictures and getting a shot of some deepsky object through the telescope. The DSO won and I took about eight 3 minute exposures of the Veil Nebula.
A star detonated here between five and eight thousand years ago. The gaseous wreckage continues to expand into the interstellar medium, carrying heavy elements which might get incorporated into a future generation of star formation and perhaps planets capable of supporting life. The Veil Nebula covers a huge area of the sky; there's a clear 2.5 degrees between the east and west portions of the nebula. That's big enough to fit more than 5 full-moons edge to edge!
The only big DSO left that I want to photograph is the Heart Nebula in Cassiopeia; hopefully I'll get a chance tonight with a clear sky.
Dr Adrian Jannetta
Guitar strummin' explorer of the universe. Mild mannered maths teacher by day and astronomer by night.