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ORION - the Hunter - Ori

Date & Time
Angular separation Rigel - Betelgeuse = 18°
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Click on a star name for more informations        
NameMagn.Dist. (L.Y.)Temp.°KC.TypeGreekConst.
Rigel0.1291012.400 B8BetaOri
Betelgeuse0.503103.280 M1AlphaOri
Bellatrix1.6436023.200 B2GammaOri
Alnilam1.701.21028.000 B0EpsilonOri
Alnitak2.051.12030.400 O9ZetaOri
Saiph2.066828.000 B0KappaOri
Mintaka2.231.30030.400 O9DeltaOri
Nair al Saif2.771.81030.400 O9IotaOri
Tabit3.1923.86.480 F6Pi 3Ori
Saif al Jabbar3.361.42025.600 B1ETaOri
Meissa3.542.17032.800 O8LambdaOri
Thabit4.621.81028.000 B0UpsilonOri
orion nebulaThe Great Nebula.

Many other much larger nebulae than M42 in Orion are known, but none offers us so intimate a view of a nearby stellar nursery. To the eye the appears as a misty patch around the central star of the line of three which form Orion's sword. Binoculars or a modest telescope will show that these three “stars” are loose groups of several individuals some of which can be seen in this photograph.The central group of stars, the Trapezium cluster, is hidden in the glow of the Orion Nebula, but these stars are responsible for producting the nebula. It is the high concentration of dust and gas in this part of the sky that has resulted in the formation of the stars, so the Orion Nebula is no random association of bright stars and dusty gas. (Royal Observatory Edinburgh).

horseheadThe Horsehead Nebula region.

This distinctive red emission nebula (IC 434) is the result of radiation from Sigma Orionis interacting with the surface of a dusty cloud of gas (B 33) from which project the dark shape of the head of a horse. The bright small nebula close and left of the Horsehead in our image is the reflection nebula NGC 2023, which must also lie in front of the dark nebula. Sigma is the second brightest star in the picture and is at about the same distance from the Sun as the nebula.The brightest star here is Zeta Orionis (Alnitak), easily visible to the unaided eye as the eastermost star in the line of three that form Orion's Belt. horsehead namedPartly obscured by the glare of Zeta is the curious yellowish nebula NGC 2024, the Christmas Tree emission nebula, whose energy comes from a star hidden in the dark lane, while other nebulae simply reflect the light of embedded hot stars and appear blue. (Photograph by David Malin, Anglo-Australian Telescope).Barnard 33 
Barnard 33
Dark Nebula

M43 is part of the M42 Nebula complex, separated from the main core of the nebula by a dark lane called the "Fish Mouth" by observers. Having the distinct shape of a comma, M43 is illuminated by the 6.9 magnitude star n Orionis. M43 was observed by De Mairian before Charles Messier added it to his famous list.
NGC 1973 
NGC 1973-75-77 in Orion is located just north of M42. It is an amazing complex of blue reflection nebulae mixed with dark lanes and red emission nebulae. The blue color comes from reflected starlight scattered by dust. It is often overlooked because of its spectacular neighbor, but is outstanding in its own right, being one of the brightest reflection nebulae in the sky.

CANIS MAJOR - the Greater Dog - CMa

Date & Time
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NameMagn.Dist. (L.Y.)Temp.°KC.TypeGreekConst.
Sirius -1.468.69.680 A1AlphaCMa
Adhara1.5057023.200 B2EpsilonCMa
Wezen1.842.5206.240 F8DeltaCMa
Mirzam1.9872025.600 B1BetaCMa
Aludra2.452.51016.000 B5EtaCMa
Furud3.0228623.200 B2ZetaCMa
Muliphein4.121.00012.400 B8GammaCMa
Angular separation Sirius - Adhara = 12°
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canis maior
M 41 
M 41
NGC 2287
Open Cluster
Magn. 4.6
Dist. 2280 l.y.
80 stars from 7th magnitude

CANIS MINOR - the Lesser Dog - CMi

Date & Time
Angular separation Procyon - Gomeisa = 4°
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NameMagn.Dist. (L.Y.)Temp.°KC.TypeGreekConst.
Procyon0.3811.26.600 F5AlphaCMi
Gomeisa2.911012.400 B8BetaCMi

TAURUS - the Bull - Tau

Date & Time
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NameMagn.Dist. (L.Y.)Temp.°KC.TypeGreekConst.
Aldebaran0.85604.200 K5AlphaTau
Nath1.6514013.600 B7BetaTau
Alcyone2.8738513.600 B7EtaTau
Al Hecka3.0049018.400 B4ZetaTau
Ain3.531504.940 G9EpsilonTau
Hyadum I3.651164.800 K0GammaTau
Hyadum II3.761554.800 K0DeltaTau
Angular separation Nath - x Tauri = 33°
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NameMagn.Dist. (L.Y.)Temp.°KC.TypeGreekConst.
Alcyone2.8738513.600 B7EtaTau
Atlas3.6338512.400 B8-Tau
Electra3.738514.800 B6-Tau
Maia3.8738512.400 B8-Tau
Merope4.1838514.800 B6-Tau
Taygeta4.338514.800 B6-Tau
Pleione5.0938512.400 B8-Tau
Celaeno5.4638513.600 B7-Tau
Asterope5.7638512.400 B8-Tau

pleiades photo
The Pleiades, M 45, Open Cluster.
The Pleiades are one of the finest and nearest examples of a reflection nebula associated with a cluster of young stars. The cluster itself is a group of many hundreds of stars about 385 light years from Earth in the northern constellation of Taurus and has been recognized since ancient times. Seven of the brightest stars are quite easy to see with the unaided eye and bear the names of the Seven Sisters, the daughters of Atlas. The nebulosity seen here is light reflected from the particles in a cloud of cold gas and dust into which the cluster has drifted. It appears blue because these tiny interstellar particles scatter blue light more efficently than the longer wavelengths of red light and it is streaky because the particles have been aligned by magnetic fields between the stars. (Royal Observatory Edinburgh).

crab grafico

crab nebula  
The Crab Nebula.
M1, NGC 1952, in the constellation Taurus.
The most conspicuous known supernova remnant. This object caused Messier to begin his catalog. The supernova was noted on July 4, 1054 A.D. by Chinese astronomers, and was about four times brighter than Venus, or about mag -6. According to the records, it was visible in daylight for 23 days, and 653 days to the naked eye in the night sky.
The Supernova 1054 was also assigned the variable star designation CM Tauri. It is one of few historically observed supernovae in our Milky Way Galaxy.

The nebulous remnant was discovered by John Bevis in 1731, according to Messier, who independently found it on August 28, 1758, and first thought it was a comet. Of course, he soon recognized that it had no apparent proper motion and cataloged it on September 12, 1758. It was christened the "Crab" on the ground of a drawing made by Lord Rosse about 1844.

The nebula consists of the material ejected in the supernova explosion, which has been spread over a volume approximately 10 light years in diameter, and is still expanding at the very high velocity of about 1,800 km/sec.
It emits light which consists of two major contributions: A reddish component which forms a chaotic web of bright filaments, which has an emission line spectrum like that of diffuse gaseous (or planetary) nebulae, and a blueish diffuse background of highly polarised `synchrotron radiation', which is emitted by high-energy (fast moving) electrons in a strong magnetic field; synchrotron radiation is also apparent in other "explosive" processes in the cosmos, e.g. in the active core of the irregular galaxy M82 and the peculiar jet of giant elliptical galaxy M87.

In 1948, the Crab nebula was identified as a strong source of radio radiation. X-rays from this object were detected in 1964 with a high-altitude rocket; the energy emitted in X-rays by the Crab nebula is about 100 times more than that emitted in the visual light. Nevertheless, even the luminosity of the nebula in the visible light is enormous: At its distance of 6,300 light years (which is quite well-determined), its apparent brightness corresponds to an absolute magnitude of about -3.2, or more than 1000 solar luminosities. Its overall luminosity in all spectral ranges was estimated at 100,000 solar luminosities.
On November 9, 1968, a pulsating radio source, the Crab Pulsar (also cataloged as NP0532, "NP" for NRAO Pulsar), was discovered in M1 by astronomers of the Arecibo Observatory 300-meter radio telescope in Puerto Rico. This star is the right (south-western) one of the pair visible near the center of the nebula in our photo. It has now been established that this pulsar is a rapidly rotating neutron star: It rotates about 30 times per second! This period is very well investigated because the neutron star emits pulses in virtually every part of the electromagnetic spectrum, from a "hot spot" on its surface. The neutron star is an extremely dense object, denser than an atomic nucleus, concentrating more than one solar mass in a volume of 30 kilometers across. Its rotation is slowly decelerating by magnetic interaction with the nebula; this is now a major energy source which makes the nebula shining; as stated above, this energy source is 100,000 times more energetic than our sun.

In the visible light, the pulsar is of 16th apparent magnitude. This means that this very small star is roughly of absolute magnitude +4.5, or about the same luminosity as our sun in the visible part of the spectrum !
This object has attracted so much interest that it was remarked that astronomers can be devided into two fractions of about same size: Those who do work related to the Crab nebula, and those who don't. The IAU symposium No. 46, held at Jodrell Bank (England) in August 1970 was solely devoted to this object. Simon Mitton has written a nice book on the Crab Nebula M1 in 1978, which is still most readable and informative (it is also source for some of the informations here).

GEMINI - the Twins - Gem

Date & Time
Angular separation Castor - Alhena = 20°
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NameMagn.Dist. (L.Y.)Temp.°KC.TypeGreekConst.
Pollux1.14354.800 K0BetaGem
Castor1.88499.360 A2AlphaGem
Alhena1.935710.000 A0GammaGem
Tejat p.2.881633.040  M3MuGem
Mebsuta2.989305.080  G8EpsilonGem
Propus3.281863.040 M3EtaGem
Alzirr3.36596.600 F5XiGem
Wasat3.53537.080 F2DeltaGem
Mekbuda3.795406.360 F7ZetaGem

Cr 89 and M 35Bottom right:
M 35 - NGC2168
Open Cluster
Magn. 5.1 - Dist. 2840 l.y.
200 stars from 8th magnitude
Top left:
Cr 89 - Open Cluster
Magn. 5.7

AURIGA - the Charioteer - Aur

Date & Time
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NameMagn.Dist. (L.Y.)Temp.°KC.TypeGreekConst.
Capella0.08415.500 G5AlphaAur
Menkalinan1.9729.360 A2BetaAur
Bogardus2.628210.000 A0ThetaAur
Al Kab2.692674.440 K3IotaAur
Almaaz2.994.6607.400 F0EpsilonAur
Hoedus II3.1719920.800 B3EtaAur
Hoedus I3.755304.320 K4ZetaAur
Angular separation Menkalinan - Hassaleh = 16°
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M37. NGC 2099. Open Star Cluster.
Visual Magnitude 5.6
Membership number 150
Angular diameter 14.0"
Distance 4.700 L.Y.
Linear diameter 25 L.Y.
Type B9
Magnitude of the brightest star 11.0
M36. NGC. Open Star Cluster.
Visual Magnitude
Membership number
Angular diameter
Distance L.Y.
Linear diameter L.Y.
Magnitude of the brightest star
Thomas V. Davis photo
M38. NGC. Open Star Cluster.
Visual Magnitude
Membership number
Angular diameter
Distance L.Y.
Linear diameter L.Y.
Magnitude of the brightest star
Michael Richmann photo

IC 405 named The Flaming Star Nebula 
M38 - IC 417 - IC 410 - IC 405
Thomas V. Davis photo
The Flaming Star Nebula 
IC 405 (also known as the Flaming Star Nebula, SH 2-229, or Caldwell 31) is an emission/reflection nebula in the constellation Auriga, surrounding the bluish star AE Aurigae. It shines at magnitude +6.0. The nebula measures approximately 37.0' x 19.0', and lies about 1,500 light-years away. It is believed that the proper motion of the central star can be traced back to the Orion's Belt area. The nebula is about 5 light-years across.
Jorge Garcia photo

CANCER - the Crab - Cnc

Date & Time
Angular separation Altarf - Iota Cancri = 21°
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Click on a star name for more informations        
NameMagn.Dist. (L.Y.)Temp.°KC.TypeGreekConst.
Altarf3.522904.320 K4BetaCnc
Asellus Aus.3.941304.800 K0DeltaCnc
Acubens4.251368.400 A5AlphaCnc
Asellus Bor.4.662049.680 A1GammaCnc
Tegmine5.63846.240 F8Zeta 1Cnc
m 44 
The Praesepe or Beehive Cluster
M 44 - NGC 2632 - Open Cluster
Dist 577 l.y. - Magn. 3.7 - 200 stars
m 44 grafThis famous cluster, M 44, is also called Praesepe (Latin for "manger"), or the Beehive cluster. It is also one of the objects easily visible to the naked eye, and thus known since prehistoric times. Some ancient lore is associated with it: Greeks and Romans saw this "nebula" as the manger (Greek: Phatne) associated with two asses who eat from it, Asellus Borealis, the Northern Ass and Asellus Australis, the Southern Ass.
Galileo has first resolved this "nebulous" object, and reported: "The nebula called Praesepe, which is not one star only, but a mass of more than 40 small stars." With larger telescopes, more than 200 of the 350 stars in the cluster area have been confirmed as members.
According to the new determination by ESA's astrometric satellite Hipparcos, the cluster is 577 light years distant, and its age was estimated at about 400 million years. Curiously, both this age and the direction of proper motion of M44 coincide with that of the Hyades, another famous naked-eye and longly known cluster, which however was neither included in Messier's list nor in the NGC and IC catalogs. Probably these two clusters, although now separated by hundreds of light years, have a common origin in some great diffuse gaseous nebula which existed 400 million years ago.Consequently, also the stellar populations are similar, both containing red giants (M 44 at least 5 of them) and some white dwarfs.

m67M 67 - NGC 2682
Open Cluster
Magn. 6.8 - Dist. 2.710 l.y.

M67 is one of the oldest known open clusters, and by far the oldest of Messier's open clusters, being aged at 4.0 billion years. Note: This is still less than the age of our Solar System, but open clusters usually get destructed much faster. It has been calculated that M67 can expect to exist as a cluster for about another 5 billion years. Only few known open clusters were found to be older, among them probably NGC 188 (Cepheus) at about 5 billion years, longly quoted as the oldest known cluster, and NGC 6791 (Lyra), which is about 7 billion years old, and is currently the oldest known open cluster in our Milky Way galaxy. The total number of stars in M67 is probably at least about 500.

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