Bear keeper

Bearkeeper constellation
Latin name	Boats
Latin genitive	Bootis
Abbreviation	Boo
Right ascension	13 h 35 m 49 s to  3 h 49 m 28 s
declination	+ 7 ° 21 ′ 38 ″ to  + 55 ° 02 ′ 42 ″
surface	906.831 deg² rank 13
Completely visible	90 ° N to 35.3 ° S
Observation time for Central Europe	November - September
Number of stars brighter than 3 mag	3
Brightest star (size)	Arcturus (-0.04)
Meteor streams	Quadrantids Alpha bootids June bootids
Neighboring constellations ( clockwise from north )	Dragon Big Bear Hunting dogs Berenike's hair Virgin Snake (head) Northern crown Hercules
swell	IAU ,
Engraving from the star atlas by Johann Elert Bode

The Bear Keeper is a bright constellation north of the celestial equator , near the Great Bear . The common name of the constellation is Bootes [ boˈoːteːs ] (in English the trema is sometimes used, "Boötes", to prevent the speaker from pronouncing the double "o" with the sound "u", which in German however leads to confusion with can lead to an umlaut), and comes from Latin bootes from ancient Greek βοςτης boōtēs , who plows with bulls. The translation cattle shepherd is also occasionally used for the picture.

The bear guardian is unusually rich in double stars , some of which (e.g. δ, ι and µ bootis) can be easily separated with binoculars . The constellation hardly contains star clusters and nebulae.

description

The Bear Guardian constellation as seen with the naked eye.

The Bear Guardian is a striking constellation in the spring and summer skies . His figure represents a slightly curved male figure, whose main stars 1st to 3rd size are reminiscent of a child's kite or a large ice cream cone.

He stands between Hercules and the Virgin . To find it, you can use the Big Dipper ( Big Bear ) as a guide. By lengthening the arc of the drawbar stars , the striking reddish arcture is achieved, which is not only the brightest star of the bear guardian, but of the entire northern sky.

The northern part of the bear guardian is circumpolar in the middle latitudes .

history

The Bear Guardian is one of the 48 constellations of ancient Greek astronomy that were already described by Ptolemy .

The name "Bear Guardian" (Greek: Ἀρκτοφύλαξ Arktophýlax ) refers to the proximity to the constellations of the Big and Little Bear and is also related to the constellation of hunting dogs as a mythological embodiment of the companion dogs of the ox driver or bear guardian. The main star of the constellation, Arcturus, seems to follow the “tail” of the Great Bear in the sky . The star β Bootis (incorrect assumption from Arabic as “Nekkar” instead of correctly “baqqār”) also bears the name “Ox driver”. Ancient and medieval authors use a. a. the names ancient Greek Βοητης , Boōtēs / Latin. Bootes (see e.g. Homer, Od. e, 272; Arat, 91/93 / fr. 16, 1–2 = Cicero, De natura deorum 2, 42, 109: Arctophylax , vulgo qui dicitur esse Bootes, / quod quasi temone adiunctam prae se quatit Arctum. Ovid, Met. 10, 450; Ovid, Fasti 2, 1, 152–192 (153: Custodem protinus Ursae / Adspicies geminos exscruisse pedes (for the constellation pops up "lying down" in such a way that the legs quickly appear one behind the other), esp. 191; 3, 403–406 (... sive est Arctophylax, sive est piger individuelle Bootes ...); 5, 733 (Auferat ex oculis veniens aurora boats); 6, 235f. Ovid, Phaenomena 91–95, 579–585, 721–723.)), because presented as the leader of the big chariot (Greek βοῦς bous, Latin bos = ox), he drives the seven Oxen (the stars of our Big Dipper , according to Varro "septem triones") around the celestial pole every 24 hours; gr. Ἀρκτοφύλαξ Arktophýlax / lat. Arctophylax, because presented as the leader (φύλαξ phylax: guardian) of the great bear (gr. ἄρκτος = bear; gr. Ἄρκτος / lat ) (see e.g. Ovid, Trist. 1, 10, 15: Custos Ursae; Vitruv 9, 4: Custos; Seneca, Thy. 874: custos sui tardus plaustri.) Occasionally, Latin Arcturus (from the Greek Ἀρκτοῦρος , from οὖρος ouros = guardian) used for the constellation.

With the introduction of the official boundaries of modern constellations by the International Astronomical Union (IAU), two old constellations were dissolved in favor of the bear keeper. In the northern part of the constellation, on the border with the Dragon , there was the constellation Wall Quadrant , after which the meteor shower of the Quadrantids is named, and in the south, on the border with Virgo , there was the constellation Mount Maenalus .

Meteor streams

In the bear guardian lies the radian of the Quadrantids , a meteor shower that reaches its maximum on January 3rd of each year, at which 40 to 200 meteors can be observed every hour.

mythology

There are several versions of the mythological origin of the constellation.

An ancient myth sees the bear guard as Arkas (Ἀρκάς), the son of Zeus and the nymph Callisto . To save her from Hera's revenge, he turned her into a bear . When Arkas ignorantly wanted to kill them while hunting, Zeus carried them both to heaven.

According to another tradition, the bear keeper is Philomelos , the son of Iasion and Demeter , who invented the cart and the ox- drawn plow. According to Catherine Tennant, the ox driver represents the transition from nomadism to sedentary ancient farming.

A third version sees the bear guardian Ikarios , whom the wine god Dionysus initiated into the art of viticulture. Ikarios went out one day to sell the grape juice. When he poured the previously unknown drink to a group of shepherds, they believed Ikarios was trying to poison them and killed him. Erigone , the daughter of Icarius, then hanged herself from mourning. Dionysus immortalized Ikarios and his daughter in heaven, who can be seen as a virgin near her father.

In Mesopotamian mythology, the bear keeper is the zodiac sign of the god Enlil .

Celestial objects

Stars

B.	F.	Names or other designations	Apparent brightness (mag)	Absolute brightness (Mag)	Lj	Spectral class
α	16	Arcturus , Arcturus, Haris el sema	−0.04	−0.31	36.7	K2 III
ε	36	Izar , Mirak, Pulcherrima	2.35	−1.69	210	K0 II + A2 V
η	8th	Mufrid	2.68	2.41	37	G0 IV
γ	27	Seginus , Ceginus, Haris	3.03	0.96	85	A7 III
δ	49	Delta Bootis	3.46	0.69	117	G8 III
β	42	Nekkar , Nakkar, Meres	3.49	−0.64	148	G8 III
ρ	25th		3.57	0.27	149	K3 III
ζ	30th		3.78
θ	23	Asellus primus	4.04		47	F7 V
υ	4th		4.05
λ	19th		4.18		97	A0p
μ	51	Alkalurops , incalunis, clava, venabulum	4.31		120
σ	28		4.47
π 1	29		4.49
τ	49	Tau bootis	4.50	3.53	50.8	F6 IV
ψ	43		4.52
κ	17th	Asellus Tertius	4.54		155	A8 IV + A5
ξ	37	Xi Bootis	4.59		22nd	G7 Ve + K5 Ve
ο	35		4.60
ι	21st	Asellus Secundus	4.75		97	A9 V + A2
ω	41		4.80
A.			4.80
d	12		4.82
i	44		4.83
e	6th		4.92
c	45		4.93
ν 2	53		4.98
ν 1	53		5.04
φ	54	Ceginus	5.25
H	38	Merga , Marrha, Falx Italica	5.7		160	F6 IVs

Arktur (α Bootis) is the brightest star in the northern sky and the third brightest star in the sky. It is a red giant of the spectral class K2 with 30 times the diameter of our sun . At a distance of 36.7 light years , it is the closest giant star. Its high proper motion of 2.28 arc seconds per year was discovered by Edmond Halley .

The name Arctur is derived from the Greek and means something like "hunter who keeps an eye on the she-bear". The Arabic name Haris el sema means "ruler of heaven".

The stars θ ι and κ Bootis have the Latin names Asellus Primus , Secundus and Tertius , which means first, second and third donkey, respectively.

λ Bootis (Lambda Bootis, HR 5351) is the prototype of a class of stars, the Lambda Bootis stars , with a special chemical composition of their surface, and was discovered in 1943 by William W. Morgan , Philip C. Keenan and Edith Kellman in in their "Atlas of Stellar Spectra". This is very poor in some metals and has the same abundance of elements as the surrounding interstellar gas. The reason for this is believed to be that when the star traverses dusty areas, its radiation pressure pushes interstellar dust in front of it and collects interstellar gas.

Double stars

system	Apparent brightness (mag)	distance
ε	2.5 / 4.9	2.8 "
δ	3.5 / 7.8	105 "
η	4.3 / 7.1 / 7.8	108 "
ζ	4.5 / 4.6	0.7 "
κ 2	4.5 / 6.7	13.6 "
τ	4.5 / 11.0	14.4 "
ξ	4.7 / 7.0	6.0 "
ι	4.8 / 7.7	38.5 "
π	4.9 / 5.8	5.5 "
ξ	4.8 / 6.9	6.6 "
ν	4.98 / 5.04	14 '
44	5.1 / 7.0	2.2 "
39	6.2 / 6.8	2.8 "

There are a number of multiple stars in the bear guardian.

Epsilon Bootis is a binary star 150 light years away. In the telescope , a deep yellow, bright star reveals who is accompanied by a blue star. This binary star system is often referred to as one of the most beautiful. The Arabic name Izar means "belt", the Latin name Pulcherrima means "beautiful".

Eta Bootis is a triple system 55 light years away. Two of the stars can already be separated with prism binoculars . In the telescope you can see another companion in the weaker component. The origin of the name Muphrid is not clear.

Iota Bootis is a triple system at a distance of 100 light years. The two brightest stars can also be resolved into individual stars with binoculars. The weaker companion is also a variable star (see below).

The stars ν ¹ and ν ² bootis are so far apart with 14 arc minutes that they can be separated with the naked eye.

Variable stars

object	Apparent brightness (mag)	period	Type
W.	4.7 to 5.4	30 to 450 days	semi-regular
ι	6.5 to 7.1	0.2678 days	Coverage variable

W Bootis is a semi-regularly changing star 400 light years away. Its brightness fluctuates between 4.7 and 5.4 ^{m over} a period of 30 to 450 days .

Iota Bootis is an eclipsing star of the Beta Lyrae type . These are close binary star systems in an early phase of their development, in which the gas from an inflated main star flows onto the accretion disk of a companion star and periodically darkens it.

NGC objects

NGC	Apparent brightness (mag)	Type
5248	10.1	Galaxy
5466	8.0	Globular clusters
5966	12.2	Galaxy

Although the bear guardian is very extensive, it contains only a few conspicuous star clusters , gas nebulae or galaxies .

NGC 5466 is a globular cluster 50,000 light years away. A powerful binoculars or telescope is required to observe it.

Planetary systems

So far, four planetary systems have been identified in this constellation :

• BD + 36 ° 2593 with the planet HAT-P-4b (orbital period 3.06 d)
• Tau Bootis with the planet Tau Bootis A b (orbital period 3.31 d)
• HD 128311 with 2 planets (459 or 928 d)
• HD 132406 with the planet HD 132406 b (orbital period 974 d)

See also

• List of constellations

Web links

Commons : Bear Guardian Constellation  - Collection of images, videos and audio files

• Cross reference for 61 stars in the constellation.

Individual evidence

1. ^ Wilhelm Pape , Max Sengebusch (arrangement): Concise dictionary of the Greek language. 3rd edition, 6th impression, Vieweg & Sohn, Braunschweig 1914. 1914, accessed on January 3, 2018 . 
2. ↑ Rotatable star map, KOSMOS
3. ↑ Article in the DLF http://www.deutschlandfunk.de/bootes-der-rinderhirte.732.de.html?dram:article_id=106606
4. ^ Wilhelm Pape , Max Sengebusch (arrangement): Concise dictionary of the Greek language. 3rd edition, 6th impression, Vieweg & Sohn, Braunschweig 1914. 1914, accessed on January 3, 2018 . 
5. ↑ (More common, especially later, is the use (only) for the name of the brightest star (in the left "knee" of the constellation). In Hesiod, Erg. 566, 610 the reference (star or constellation) is unclear.)
6. ↑ Catherine Tennant: Great moments. A practical guide through the night sky and its myths , Wunderlich / Rowohlt 1994
7. ↑ Michael v. Streck (Ed.): Reallexikon der Assyriologie und Vorderasiatischen Aräologie. tape 2 , p. 382 ff .
8. ↑ Stars and Space, April 2006: Lambda Bootis Stars - Vacuum Cleaner of the Interstellar Medium