Ursa Major


The Ursa Major is a polar constellation and you may see it over the horizon any time, but highest over hem and so good it been seen at a springs and summers nights.
Over hem are the constellations Boots, Canes Venatici, Leo Minor, Linx and Ursa Minor.
It the Ursa Major constellation, over clears nights, with the naked eye, way see 125 stars, but 20 of them are the Brighter of this 4th star magnitude. The bring stars are 7 and them know to every character figure to this constellation: Ursa Major. But is wanting a big effort to fancy, in order to see in this figure: the big bear, want in the stars shards himself. The ? and ? stars, are index - the unreal line meditate over them. The constellation Ursa Major- from Greece, see itself high over the Nord side to horizon.

URSA MAJOR the Great bear. The third-largest constellation in the sky. Its central feature is the seven stars that make up the familiar shape variously called the Plough or the Big Dipper, the best known of all star patterns, although why sî many people, including the North American Indians, visualized this group as a bear remains a mystery. In Europe the pattern was seen as awagon or chariot. Others, notably the Arabs, viewed the dipper shape not as a bear, but as a bier or coffin. In Greek mythology the bear àre presented Callisto, who was turned into a bear in punishment for her illicit love affair with Zeus. The stars of the Big Dipper, except Alkaid and Dubhe, are moving together through space. Two stars in the bowl of the dipper, Merak and Dubhe act as a pointer to Polaris, the North Pole Star in neighbouring Ursa Minor. The handle of the Big Dipper points to the bright star Arcturus in Bootes. At Ilk 03.3m, +35° 58', lies the mag. 7.5 red dwarf Lalande 21185, which is the Sun's fourth- closest stellar neighbour, 8.2 l.y Away. Its name comes from its number in a catalogue drawn up by the 18th-century French astron-omer Joseph Lalande. Ursa Major contains numerous galaxies, but only a few of them are easily visible in amateur telescopes.
Alpha Ursa Majors, Ilk 04m +62°, (Dubhe, 'the bear'), mag. 1.8, is a yellow giant 1081.y.away. It has a clots mag. 4.8 companion that orbits it every 45 years. The two can be split in 220 mm aperture, apart from the few years either side of 2011, when they are at there closest.
Beta UMa, lIb 02m +56°, (Merak, 'flank'), mag. 2.4, is a whit star 781.y. away.
Gamma UMa, Ilh 54m +54°, (Phccda, 'thigh'), mag. 2.4, is a white star 88 1y away.
Delta UMa, 12h 15m +57°, (Megrez, 'root of the tair), mag. 3.3, is a white star 62 I.y. away.
Epsilon UMa, 12h 54m +56°, (Alioth), mag. 1.8, is a white star with a peculiar spectrum and of unccrtain distance.
Zeta UMa, 13h 24m +55°, (Mizar), mag. 2.3, is a celebrated multiple star. Keen eyesight, or binoculars, reveal its mag. 4.0 companion Alcor. Mizar is 60 I.y. from Earth and Alcor 90 ly away, too far apart to make this a genuine binary. However, a small telescope reveals that Mizar has another mag. 4.0 companion closer to it, which definitely is related. The Italian astronomer Giovanni Riccioli first saw this star in 1650, making Mizar the first double star to BC discovered telescopically. Mizar was also the first star discovered to be a spectroscopic binary, by the American astronomer E. C. Pickering in 1889. The companion of Mizar is another spectroscopic binary, as is Alcor, making this a highly complex group. (See the diagram on page 245.) 1/ (eta) UMa, 13h 48m +49°, (Alkaid or Benetnasch, both from the Arabic for' leader of the mourners'), mag. 1.9, is a blue-white star about 100 I.y. away. illicit love affair with Zeus. The stars of the Big Dipper, except.


The Ursa Major - the brightest, the most remarkable, the most ancient of the defined by people constellation on the north sky.Who does not know the Ursa Major! It is easy to explain, why it is big, but who knows why it is called "bear"!
There are enough reasons. That the name bear existed more than 100 000 years ago. The brightest stars of this constellation have differently orientated of their own's moving. That's why their total configuration is changing very slightly for centuries. The outlines of these stars have noting to do with a "bear". They resemble a big ladle or a pot with a handle.
100 000 years ago the figure of the bright stars had been formed a great bear.
The outlines picture of a "bear" is created by six stars, while the 7th one looks like a mottle.
100 000 ago people really saw a "bear" in Ursa Major.
There is really an ancient myth about Ursa Major, which explains the popular by of this name.
The supreme god on the Greeks - Zeus fall in love with the nymph Callisto.
Zeus' jealous wife - Herra, turned the nymph in to a bear, but Zeus saved his beloved and she became a constellation.
But it was turned out that the 'bear'-constellation had a long tail, which real bears had never had and which astronomers had to draw on their maps. Here the mythological interpretation were forced to step in again tens threw the bear Callisto on the sky hanging it for the tail. This is now the tail had been made longer.
This is a romantic story.But is it possible to explain why the Indians called this constellation 'bear' too.
Gradually astronomers related that each star is a whole world and that the relationship between the stars-constellation is just a conventionality.In fact they came to the conclusion that there was no such relationship as a rule.
The star ? from Ursa Major, for example, is fourth times away from us that the star eta from the same constellation. There is meteoritic shower going through Ursa Major, which called Ursidi, intended for Ursa Major.

The Ursa Majors objects

Double star in Ursa Major
Winnecke4 12h 20m.0 +58?

Basic data: In searching for a nebula said by the 17th-century observer Johann Nevelius to this vicinity, Messier could find only a pair of faint stars, to with he nevertheless gave a number in his catalogue. The two components are of visual magnitudes 9.0 and 9.3, and their separation on the sky is 49 seconds of arc.
Visual appearance: The double star was very easy with the 4-inch refractor at 25x. It shows the 13th- magnitude galaxy NGC 4290 forming a right triangle with 6th-magnitude 70 Ursae Majors and M40. This barred spiral, about 2 by 1 minutes in size, could not be seen in the 4-inch.

Galaxy in Ursa Major
NGC 3031 9h 51m.5 +69? 18'

Basic data: Messier 81 has a total magnitude of about 7.9 visually and 8.4 photographically. Its extreme dimensions on photographs are 21-by-10 minutes of arc. This splendid Sb spiral is about 7,000,000 light-years distant, according to Allan Sandage in 1954. As is to be expected for such a relatively galaxy, the red shift is small: 88 kilometers per second.
Visual appearance: In the 5-inch refractor, a beautiful object! As seen in that telescope, M81 has the most strongly granular central region of almost any galaxy. The outer parts are mottled and uneven in brightness and texture. Two other visual characteristic are the fairly sharp outer edge and the bright arcs at the ends of the major axis.

Galaxy in Ursa Major
NGC 3034 9h 51m.9 +69? 56'
Basic data: An irregular galaxy about 9-by-4 minutes of arc in extent, M82 is of magnitude 8.8 visual and 9.4 photographically. About the same distance from us as its neighbor M81, it also has a small spectral red shift, 322 kilometers per second. The finder chart is on the previous page.
Visual appearance: A gem! In a low-power field, it forms a beautiful pair with M81. In shape and color M82 is a silver sliver, with its brightest part off-center as in the drawing. The dark absorption band seen in the photograph was not detected in the 4-inch. This telescope showed the galaxy to by highly uneven in brightness but with little or none of the grainy texture seen in M81.

Planetary nebula in Ursa Major
NGC 3587 11h 12m.0 +55? 18'
Basic data: M97 has a total visual magnitude of about 11, though it is harder to see than this might suggest, because its light is over an area about 3 minutes of arc across. This planetary is about 1? light years in diameter, and lies at a distance of 2,000 light-years, according to K. M. Cudworth.
Visual appearance: At 120x in the 4-inch refractor of author John Mallas, M97 appears as a rather large gray oval. It is practically featureless, though there is a slight indication of two dark areas (the Owl's eyes), which are exaggerated in the drawing.


Galaxy in Ursa Major
NGC 5457 14h 01m.4 +54? 35'

Basic data: Through an 18th-century error, this galaxy was also called M102. It is a very large, bright spiral seen face on. Appearing 22 minutes in diameter on photographs, it has a total light equivalent to an 8th-magnitude star. Its distance is about 15 million light-years.
M101 is a late-type spiral of class Sc, with narrow spiral arms only about 900 light-years across and containing many hot, blue stars.
Visual appearance: A beautiful object. In the Mallas 4-insh it appears only about half as large as on photographs. Low powers are best. The clearly seen central region has a fluffy texture and a silvery hue. Surrounding this area is a soft sheen containing some nebulous patches.

Galaxy in Ursa Major
NGC 3556 11h 08.7 +55? 57'

Basic data: Seen nearly edgewise, 10th-magnitude M108 is very elongated, 8-by-1 minutes of arc. With greatly foreshortened spiral arms and no pronounced nuclear bulge, it is a Sc-type spiral, about 25 million light-years away and receding from us at some 760 kilometers a second.
Visual appearance: A silver-white beauty for small telescopes, saucer-shared and fairly well defined. The central region is quite bright and irregular, surrounded by light and dark nodules. Mallas found it difficult to match and the photograph, so it is not certain is with M97.

Galaxy in Ursa Major
NGC 3992 11h 55m.0 +53? 39'
Basic data: This conspicuous barred spiral lies 2/3 degrees southeast of Gamma Ursae Majoris. It is about 7-by-4 minutes of arc on long-exposure photographs. Through its bright central core extends a stubby bar from the ends of which trail narrow, sharp spiral arms. The total magnitude of M109
is about 9?.
Visual appearance: A splendid galaxy for small apertures, though only the brighter central region can be seen. It is pear-shaped, whit a strong suspicion of a granular texture, and close to a faint star whose glow obliterates the outer region. The finder chart is with M106.

Lesson for observation of the stellar sky
Theme of îbservation: Observation of the constellation Ursa Major
I. Purpose of the observation:
Students can be/should:
1. The schoolboys can orientates themselves for the position of the constellation UMa on a stellar sky,
2 The schoolboys makes registration to the visible rotation of the stellar sky, during 2 hours;
II. Tasks
1. Determine the border of the visible stellar magnitude for the night of the observation, by standard area 16 (?CVn, ?-? UMa).
2. Make visual observation to the constellation UMa. Discover the typical figure on the constellation. Collate the areas on the constellations: Ursa Major and CVn.
3. With a telescope make observation to the remarkable objects, inaccessible for naked eyes.
4. Make observations to the changes in to the positions of the constellations: Ursa Major and Ursa Minor for one night (during 2 hours). Make
III Necessary means and materials: map to the sidereal sky; lantern; astronomical almanac, telescope and watch.
IV. Basic knowledge:
Concept for a magnitude; a constellation; the configuration to the constellations: Ursa Major, standard areas; celestial sphere; sidereal map
VI. Theory
The gloss of stars express in the special conditional scale, gated in still in II in BC by the Greek astronomer Hiparhh. This scale is called as a scale of stellar magnitudes. Title of a scale, maybe, also is not absolutely successful, as the scale does not evaluate linear dimensions of stars but only allows comparing one another gloss of stars. Presently scale of stellar magnitudes considerably is advanced and for definition of gloss of stars the precise optical aids is used.
The scale of stellar magnitudes is based on perceptions of a light by an eye. It appears, the human voice legibly marks discrepancy of intensity of light sources, if one of them approximately in 2,5 times more brightly other.
To the brightest stars Hiparhh as attributed the maiden stellar magnitude; following on gradation of gloss it has counted as stars of the second stellar magnitude. The stars are more gentle than stars of the second stellar magnitude in 2.5 times, were called as stars of the third stellar magnitude and etc.; to stars on a limit of visibility a unaided eye was call the sixth stellar magnitude.
The stars are figured on maps by mugs of different diameters depending on their gloss expressed, as we already know, in stellar magnitudes. Than more brightly star, that the its stellar magnitude is less, the large circle she are figured. The special signs mark the dual and variable stars, stellar congestion and nebulas. The arguments are given to which one on fields of a map.
All the sky can be dissected on plots inside which one star as though are clustered in different figures. These sky regions are called as constellations.
That the map of constellations on a map did not differ from their view on a sky, we exhibit a stellar sky as by transparent sphere. Though actually celestial sphere does not exist also us environs boundless room, nevertheless impression about it form because the celestial heavenly bodies are expelled from the Earth on enormous spacing intervals discontentedly apparent to us identical.
No wonder that at such huge spacing intervals all extraterrestrial heavenly bodies are represented us finding on an internal surface of imaginary celestial sphere a critical, but enormous radius, and we involuntarily think at its center.
To orient on celestial sphere it is possible with the help of the parties of horizon and point of zenith (point on celestial sphere disposed directly above a head). Blue pole of a world is disposed above a point of a north of horizon at the altitude, equal geographic latitude of a place of supervising. The site of northern world "is noted" on a sky by a Polar star.

Our observation:
1. In the night at 05.09.2002 our group (Dobromir, Iglika, and Greta, with leader miss Ivanova) organised an observation on stellar sky. It was a 20 hour summer local time (17 UT) and to the place of our UAO - Silistra
2. We determined border of the stellar magnitude like 5m,3 because we numbered a 9 stars on a standard area 16.
3. We maked observation to the remarkable objects on the constellation Uma, with a telescope.
4. We make observations to the changes in to the positions of the constellations: Ursa Major and Ursa Minor for one night (during 2 hours).

This isto the positions of the constellations at 20:00 hour.

This is to the positions of the constellations at 22:00 hour.

Team: Dobromir Ivalinov Hristov, Greta Dimitrova Nicolova, Iglica Dimitrova Georgieva

Leader: Nelly Ivanova

adres: str. "7-th September" 61, P. B. 134, Silistra 7500 Bulgaria, e-mail: nao_ggalilej@mail.bg