WADHURST ASTRONOMICAL SOCIETY

NEWSLETTER April 2002

INDEX: MEETINGS, OTHER NEWS, CONTACTS,

MEETINGS

LAST MONTH

The last meeting of the Wadhurst Astronomical Society was held on 13th March. The speaker was Konrad Malin Smith, who gave us a talk on the subject of Supernovae. Konrad started with a brief introduction into Supernovae in general, including the differences between the two types. Type II supernovae were the main subject for the talk and we even listened to an audio recording of a pulsar. Konrad had a number of slides to illustrate the talk, many of which were taken on his various trips to foreign countries. The list of supernovae and their remnants included the Crab Nebula, Casseiopia A, M101, NGC 5253, Zeta Aurigae, SN1987A and Eta Carinae. The talk did become fairly technical detailing the chemical reactions that take place in the death of a star that form all the various elements that are found. After a short break for refreshments, Konrad continued with a look at what actually happens when the core of a star collapses. This was demonstrated with the use of two superballs to great effect! This then led into a discussion about neutrinos, and the ways in which they can be detected. Konrad pointed out that in a Supernova explosion only 0.01% of the energy is visible light, the other 99.9% being neutrino energy. It has been calculated that 10 to the power 54 neutrinos are given of in a supernova! Konrad then looked briefly at a number of different stars that may become supernovae in the future. The talk finished with a quick look at the pistol star that is so massive that it will become a black hole.

After the talk there were a few society notices which as usual have been dealt with under separate headings below.

NEXT MONTH

The next society meeting is on 10th April, at the usual time of 7:30 pm. The speaker this time will be Greg Smye-Rumsby of Orpington Astronomical Society, and the talk is intriguingly titled "What size is that?" The talk is about various astronomical objects and their true sizes sometimes in comparison to Earth objects. It has been reported from various sources that Gregg is an extremely entertaining speaker, so please make the effort to come along if at all possible.

GO TO INDEX

OTHER NEWS

SPELDHURST FETE

As has been mentioned previously this is on 22 June, and the society hopes to make an interesting exhibition for the public. The committee are therefore still looking for ideas that will make the stand as attractive and innovative as possible. One idea is that as the date falls 1 day after the summer solstice we could perhaps have a large simple illustration that shows the Earth's path around the Sun explaining why this happens. Another idea is that we could have four big posters that show what the night sky should look like at a certain time i.e. North, South, East and West. If any member has any experience, skills, know-how or suggestions please come forward. Please make any comments to any committee member at the usual meeting or contact Tim (01732 832745) or Ian (01892 784255).

COMET

At the end of the last meeting mention was made of Comet Ikeya-Zhang, which is at present visible in the Western evening sky. It is found about 90 minutes after sunset in the constellation of Pisces. It is hoped that it will become brighter and may reach magnitude 3 or 4 at the end of March. There are a couple of links that may be of interest to members: The Society for Popular Astronomy has a page with map and general info here and there is an ephemeris available here.

CONSTELLATION OF THE MONTH

Monoceros - The Unicorn

Pronunciation - mo-NOS-er-os, Genitive - mo-NOS-eh-ROW-tis, Abbreviation - Mon

Myth and Legend

Monoceros is not one of the original 48 'ancient' constellations, so the nearest it gets to myth and legend is its name itself - The Unicorn. While the constellation may have been in existence prior to the seventeenth century, its first historical reference appears in Jakob Bartsch's star chart of 1624, under the name "Unicornu". It is believed that Bartsch, who was Johannes Kepler's son-in-law, relied on earlier works, but such works have never been identified.

The stars of Monoceros are relatively dim, with only a handful of forth magnitude stars. It lies in, and around, the 'Winter Triangle' formed by the bright stars Sirius, Betelgeuse, and Procyon in Canis Minor. It takes a lot of imagination to make a unicorn out of this group of stars, and star charts depict the unicorn in several different ways, if they bother at all! Its lack of bright stars doesn't mean there's nothing of interest here. Monoceros has several celebrated deep sky objects, and even a meteor shower. The Alpha Monocerotitds are among the fastest meteors colliding with the Earth. Some of them can be very bright. The shower occurs mid to late November, with its peak around 21-23 November, when the constellation will be approximately South East by midnight.

Bright stars and Selected Deep Sky Objects

(beta) Mon is a white triple star system 470 - 590 light years away. William Herschel discovered it in 1781 and thought it 'one of the most beautiful sights in the heavens'. The smallest of telescopes should split the two main AB components, and telescopes over 100mm should split the B component to find the fainter C component. The visual magnitudes and separations are as follows: AB (4.7, 5.2; 132 degrees, 7.3"), AC: (6.1, 124 degrees, 10"). overall magnitude 4.7.

M50 (NGC 2323) - Mag: 5.9 RA:07h 03m 17.6s Dec:-08d 20' 19" This is the only Messier object in Monoceros. This large open cluster about 2500 light years away, contains about a hundred tightly grouped stars, many in pairs, triplets and small groups. It may be visible with the naked eye, so it's ideal for binoculars and small telescopes. To star hop to M50, draw a line between Sirius and Procyon, you'll find the cluster about a third of the way up from Sirius.

NGC 2264 - The Christmas Tree Cluster. - Mag: 3.9 RA:06h 41m 12.3s Dec:+09d 52' 50" - I saw this for the first time last month, when Murray pointed it out when we were on Ashdown Forrest. The brighter stars of this open cluster really do look like the lights on a Christmas Tree, albeit upside down! The Christmas Tree shape can even be seen with binoculars. To star hop to the cluster, follow a line from Bellatrix though Betelgeuse in Orion and extend it 1.5 times the separation past Betelgeuse, then move northwards 1 degree. If that fails, ask Murray! The Cone Nebula lies at the tip of the Christmas Tree Cluster. This emission nebula has a spectacular cone shape in photographs, but like the horsehead nebula, requires an aperture of at least 12 inches and a hydrogen beta filter to see it visually.

NGC 2244 - The Rosette Cluster, and NGC 2237-9 - The Rosette Nebula. - Mag: 4.8 RA:06h 32m 30.0s Dec:+04d 51' 50" - This open cluster consists of about 40 stars and is the birthplace of the nebula itself. This nebula is a super-massive cloud of gas and dust, 130 light years in diameter that contains the equivalent mass of about 10,000 Suns. At a distance of 5,500 light years, it still accounts for a full degree of sky, which is about twice the apparent size of the full moon. Although visually it will only show as circular area of faint grey smudges, long exposure colour photos show that this spectacular nebula well deserves its name. To star hop to the cluster, follow a line between Meissa and Betelgeuse in Orion, and extend it 1.5 times their separation. If you have a Telrad finder, try to center the Telrad on Betelgeuse, then move the telescope to the west about 2-1/2 Reticule diameters.

NGC 2244 also contains Plaskett's Star. The 6th Mag binary star system discovered in 1922 comprises of two giant O-type stars, each of which orbits a common centre of gravity every 14.4 days. While John Plaskett arrived at a mass of 90 Suns for each star, it is now probable that the total mass of the two does not exceed 100 Suns. Even so, this pair still stands as the most massive double star system yet discovered.

NGC 2261 - Hubble's Variable Nebula RA:06h 39m 18.2s Dec:+08d 43' 49" - This reflection nebula sporadically fluctuates in brightness in just a few weeks. Discovered over 200 years ago, but named after Edwin Hubble who studied it early last century. The variable star R Mon was thought to be responsible for the variations in brightness, but it's not that simple. Dense condensations of dust near the star cast moving shadows onto the reflecting dust seen in the rest of the nebula. As the dust clouds move, the illumination changes, giving rise to the variations first noted by Hubble. The nebula is about 2,500 light-years away, and about one light year across.

While the nebula can be seen in small scopes, it is a little tricky to find. One method I've found, but not tried, is to star-hop from epsilon Monocerotis, then up to 13 Monocerotis, then up, to the northeast, is S Monocerotis. About half way between these two, the great nebulosity surrounding S Monocerotis begins. At the extreme southern edge of this nebulosity is the distinguishing comet shape of Hubble's Variable Nebula. If anyone knows of an easy way to star hop to it please let me know!

There are a couple of links that may be of interest to members; There are some realistic views of various objects through a telescope here, and there is a site with maps and general information here

GO TO INDEX

CONTACTS

Chairman: Murray R. Barber 01892 654618 murray.barber@virgin.net

Secretary: Tim Bance 01732 832745 timbance@hotmail.com

Treasurer: Ian Reeves 01892 784255

Editor: Peter Bamblett 01732 368656 pbamblett@hotmail.com

Web site: Rob Cray rob@arcray.net

Publicity: Michael Harte 01892 783292 michael@greenman.demon.co.uk

Dir. of Obs.: Sean Tampsett 01892 667092 sean_tampsett@hotmail.com

Librarian: Joan Grace 01892 783721

Custodian of Equipment: Peter Prince 01892 836284

GO TO INDEX