天龙座

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天龙座
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缩写	Dra
所有格	Draconis
象征物	龍
赤经	15 h
赤纬	+75°
面积	1083平方度位次：第8位
亮星数目 (星等 < 3)	3
最亮星	天龙座γ 天棓四(Etamin) (视星等 2.23)
流星雨	天龙座流星雨
邻接星座	牧夫座獵戶座天琴座天鵝座仙王座小熊座鹿豹座大熊座
纬度变化位于 +90°和−15°之间可全见最佳观测月份在7月

天龍座 Draco（龍的拉丁文寫法）是北方的星座，北半球的觀星者可在天極附近看到它。它是八十八個現代星座之一，也是托勒密所定的四十八個星座之一。

[编辑] 特徵

大約在西元前二千七百年，右樞（Thuban）（天龍座α）是古埃及人所見的北極星。因為歲差，它會於大約西元21,000年再次成為極星。

雖然右樞的巴耶命名為天龍座α，它郤不是天龍座最亮的星。它的目視星等為3.65，比起最亮的天棓四（Eltanin）（天龍座γ）的亮度2.23低一度。

天龍座有幾組值得留意的雙星。天棓二（Kuma）（ν Draconis）包含了兩顆亮度4.9的星，相距62角秒；用望遠鏡便可以分辨。

R Draconis and T Draconis are 芻蒿變星 R ranges between magnitudes 6.7 and 13 with a period of 245.5 days, and T ranges between magnitudes 7.2 and 13.5 with a period of 421.2 days.

σ Draconis is relatively close to Earth, only 18.8 light years away.

The north pole of the ecliptic lies within the constellation Draco. This point is very close to the galaxy NGC 6552 and within 10 arcminutes of the Cat's Eye Nebula - NGC 6543

[编辑] Notable deep sky objects

One of the deep-sky objects in Draco is the Cat's Eye Nebula (NGC 6543), a planetary nebula that is said to look like a blue disc. There are several faint galaxies in Draco, one of which is the Lenticular Galaxy NGC 5866, sometimes considered to be Messier Object 102.

[编辑] Mythology

There are a number of myths behind the constellation Draco, due to its resemblance to a dragon [1].

In the most famous of the myths, Draco represents Ladon, the hundred-headed dragon that guarded the golden apples of the Hesperides. The eleventh of The Twelve Labours of Heracles was to steal the golden apples. Herakles killed Ladon with a poisoned arrow, allowing him to freely take the golden apples. According to the legend, Hera later placed the dragon in the sky as the constellation Draco. Due to its position and nearby constellations in the zodiac sign of Libra (i.e. Ursa Major, Ursa Minor, and Boötes), the group of constellations can be seen to tell the tale of the eleventh labour.

In another legend, Draco represents the dragon killed by Cadmus before founding the city of Boeotia. In a third legend, it represents the dragon that guarded the Golden Fleece and was killed by Jason.

In a somewhat Roman/Greek legend, the dragon pictured in the constellation of Draco was said to guard the polar star. By astronomical chance, the Dragon's Head and Dragon's Tail marks the positions of the lunar nodes, those points where the paths of the solar and lunar orbits intersect and where solar and lunar eclipses may occur. The Dragon's head refers to the ascending node, the Dragon's tail the descending node. In several cultures, an eclipse was attributed to the disappearance of the moon or sun as they were swallowed by a dragon. The fact that the stars of this circumpolar constellation never set plays an important part in its mythologies.

Very anciently, the stars of Ursa Minor were considered to represent the Dragon's wing.

[编辑] Table of leading stars

The following table lists all stars in Draco that have either a Bayer or Flamsteed designation, or are magnitude 4.5 or brighter.

Common name	Bayer designation	Flamsteed designation	Variable designation	Other designation	Right ascension (J2000)	Declination (J2000)	Magnitude
				HR 3751	09h 37m 05.2s	+81° 19' 35"	4.29
Gianfar	λ Dra	1			11h 31m 24.2s	+69° 19' 52"	3.84
		2			11h 36m 02.8s	+69° 19' 22"	5.20
		3			11h 42m 28.4s	+66° 44' 42"	5.30
		4	CQ		12h 30m 06.7s	+69° 12' 04"	4.95v
	κ Dra	5			12h 33m 29.0s	+69° 47' 18"	3.87v
		6			12h 34m 44.0s	+70° 01' 19"	4.94
		7			12h 47m 34.4s	+66° 47' 25"	5.43
		8			12h 55m 28.5s	+65° 26' 19"	5.24
		9			12h 59m 55.1s	+66° 35' 50"	5.32
	i	10	CU	ADS 9039	13h 51m 25.9s	+64° 43' 24"	4.65v
Thuban	α Dra	11			14h 04m 23.3s	+64° 22' 33"	3.65
Ed Asich	ι Dra	12			15h 24m 55.8s	+58° 57' 58"	3.29
	θ Dra	13			16h 01m 53.3s	+58° 33' 55"	4.01
	η Dra	14		ADS 10058	16h 23m 59.5s	+61° 30' 51"	2.74
		15			16h 27m 59.0s	+68° 46' 05"	5.00
		16		ADS 10129C	16h 36m 11.5s	+52° 54' 01"	5.53
		17		ADS 10129AB	16h 36m 13.9s	+52° 55' 28"	5.08
	g	18			16h 40m 55.1s	+64° 35' 21"	4.83
	h	19			16h 56m 01.7s	+65° 08' 05"	4.89
		20		ADS 10279	16h 56m 25.2s	+65° 02' 21"	6.41
Arrakis	μ Dra	21		ADS 10345	17h 05m 19.8s	+54° 28' 13"	4.92
Aldhibah	ζ Dra	22			17h 08m 47.2s	+65° 42' 53"	3.17
Rastaban	β Dra	23		ADS 10611	17h 30m 26.0s	+52° 18' 05"	2.79
Kuma	ν¹ Dra	24		ADS 10628A	17h 32m 10.6s	+55° 11' 03"	4.88
Kuma	ν² Dra	25		ADS 10628B	17h 32m 16.0s	+55° 10' 23"	4.87
	f	27			17h 31m 57.9s	+68° 08' 06"	5.05
		26		ADS 10660	17h 34m 59.5s	+61° 52' 30"	5.23
	ω Dra	28			17h 36m 57.1s	+68° 45' 29"	4.80
Dziban	ψ¹ Dra	31		ADS 10759	17h 41m 57.2s	+72° 09' 11"	4.27
		30			17h 49m 04.3s	+50° 46' 52"	5.02
Grumium	ξ Dra	32			17h 53m 31.7s	+56° 52' 22"	3.75
		35			17h 49m 27.0s	+76° 57' 46"	5.04
Eltanin	γ Dra	33		ADS 10923	17h 56m 36.4s	+51° 29' 20"	2.23
	ψ² Dra	34			17h 55m 11.2s	+72° 00' 18"	5.45
		40		ADS 11061B	18h 00m 03.4s	+80° 00' 03"	6.04
		41		ADS 11061A	18h 00m 09.2s	+80° 00' 15"	5.68
		36			18h 13m 53.8s	+64° 23' 50"	5.03
		37			18h 15m 17.0s	+68° 45' 21"	5.95
	φ Dra	43		ADS 11311	18h 20m 45.5s	+71° 20' 16"	4.22v
	b	39		ADS 11336	18h 23m 54.5s	+58° 48' 02"	4.98
	χ Dra	44			18h 21m 03.4s	+72° 43' 58"	3.57
		42			18h 25m 59.1s	+65° 33' 49"	4.82
	d	45			18h 32m 34.5s	+57° 02' 44"	4.77
	c	46			18h 42m 37.9s	+55° 32' 22"	5.04
		50			18h 46m 22.2s	+75° 26' 02"	5.35
	ο Dra	47		ADS 11779	18h 51m 12.1s	+59° 23' 18"	4.66v
		48			18h 56m 45.0s	+57° 48' 54"	5.66
	υ Dra	52			18h 54m 23.9s	+71° 17' 50"	4.82
		49			19h 00m 43.4s	+55° 39' 30"	5.48
		51			19h 04m 55.2s	+53° 23' 48"	5.38
		55			19h 09m 45.8s	+65° 58' 43"	6.25
		53			19h 11m 40.5s	+56° 51' 33"	5.12
		54			19h 13m 55.2s	+57° 42' 18"	4.99
Nodus Secundus	δ Dra	57			19h 12m 33.3s	+67° 39' 42"	3.07
		59			19h 09m 09.8s	+76° 33' 38"	5.13
	τ Dra	60			19h 15m 33.0s	+73° 21' 20"	4.45
	π Dra	58			19h 20m 40.1s	+65° 42' 53"	4.59
Alsafi	σ Dra	61			19h 32m 21.6s	+69° 39' 40"	4.68
Tyl	ε Dra	63		ADS 13007	19h 48m 10.4s	+70° 16' 04"	3.83
	e	64			20h 01m 28.5s	+64° 49' 16"	5.27
		65			20h 02m 20.3s	+64° 38' 04"	6.57
	ρ Dra	67			20h 02m 49.1s	+67° 52' 25"	4.51
		69			19h 59m 36.6s	+76° 28' 53"	6.20
		66			20h 05m 32.8s	+61° 59' 44"	5.39
		68			20h 11m 34.9s	+62° 04' 43"	5.75
		71	DE		20h 19m 36.7s	+62° 15' 27"	5.72v
		73	AF		20h 31m 30.4s	+74° 57' 17"	5.20v
		75			20h 28m 14.6s	+81° 25' 22"	5.46
		74			20h 29m 27.5s	+81° 05' 29"	5.96
		76			20h 42m 35.2s	+82° 31' 52"	5.75

Source: The Bright Star Catalogue, 5th Revised Edition

[编辑] Table of notable double stars

Designation	Right Ascension	Declination	Magnitudes
μ (Arrakis)	17h 05m 19.8s	+54° 28' 13"	5.80, 5.83
ν¹+ν² (Kuma)	17h 32m 13.3s	+55° 10' 43"	4.88, 4.87
ε (Tyl)	19h 48m 10.4s	+70° 16' 04"	3.83, 7.4

[编辑] Table of notable variable stars

Designation	Right Ascension	Declination	Range	Period
R	16h 32m 40.3s	+66° 45' 18"	6.7-13.2	245.5 days
T	17h 55m 37.4s	+58° 13' 24"	7.2-13.5	421.2 days
RY	12h 54m 28.1s	+66° 15' 52"	6.5-8.0	172 days

[编辑] Table of notable deep sky objects

Designation	Type	Right Ascension	Declination	Size	Magnitude
NGC 6504	Galaxy	17h 49m 24.0s	+70° 09' 00"	6.2'×2.3'	10.2
NGC 6543	Planetary nebula	17h 58m 33.4s	+66° 37' 59.1"	23"×17"	8.1
NGC 5866 (M102?)	Galaxy	15h 06m 29.3s	+55° 45' 47"	6.5'×3.0'	11.1

[编辑] Stars

Stars with proper names:

(11/α Dra) 3.67 Thuban or Adib or Dragon’s Tail

< الثعبان aθ-θu^cbān The basilisk

< الذئبة að-ði'bah The female wolf

(23/β Dra) 2.79 Rastaban [Rastaben] or Alwaid or Asuia

< راس الثعبان ar-rās[u] aθ-θu^cbān The head of the basilisk

(33/γ Dra) 2.24 Eltanin [Etamin, Etanin, Ettanin] or Zenith Star (or Rastaban [Rastaben], see β Dra)

< راس التنين ar-rās at-tinnīn The head of the dragon (also called Caput Draconis)

(57/δ Dra) 3.07 Altais or Nodus Secundus [Nodus II] or Aldib

< التيس at-tais The billy goat

< nōdus secundus The second knot

< الذيب\الذئب að-ðīb: The wolf

(63/ε Dra) 3.84 Tyl or Kin Yu

< 金魚 (Mandarin jīnyǘ)
(22/ζ Dra) 3.17 Aldhibah [Eldsib] or Kaou Pih or Nod (or Nodus I, see ξ Dra)

Aldhibah < ? The (two) wolves [with η Dra]
(14/η Dra) 2.73 Booboo or Aldhibain

Aldhibain < ? The (two) wolves [with ζ Dra]
(12/ι Dra) 3.29 Edasich [Eldsich, Ed Asich, Al Dhiba, Al Dhihi] – has a planet

Edasich < ? að-ðix The hyena
(1/λ Dra) 3.82 Giausar [Giauzar, Gianfar, Giansar, Gaiusar] or Juza

(21/μ Dra) 4.91 Arrakis [Errakis, Al Rakis]

< الراقص ar-rāqiş The dancer (twinkling?)

(24/ν¹ Dra) (or Kuma, see ν² Dra) 4.89
(25/ν² Dra) 4.86 Kuma
(32/ξ Dra) 3.75 Grumium [Genam] or Nodus Primus [Nodus I]

(61/σ Dra) 4.68 Alsafi [Athafi] – nearby

(?) < الصافي The clear (?) al-aθafi The cooking tripods?

(31/ψ Dra) 4.58 Dziban [Dsiban]

< ذيبان\ذئبان ðībān: Two wolves

Stars with Bayer designations:

13/θ Dra 4.01; 5/κ Dra 3.85; 47/ο Dra 4.63; 58/π Dra 4.60; 67/ρ Dra 4.51; 60/τ Dra 4.45; 52/υ Dra 4.82; 44/χ Dra 3.55; 43/Φ Dra 4.22; 28/ω Dra 4.77; 39/b Dra 4.98; 46/c Dra 5.03; 45/d Dra 4.77; 64/e Dra 5.22; 27/f Dra 5.07; 18/g Dra 4.84; 19/h Dra 4.88; 10/i Dra 4.58; 15/A Dra 4.94

Stars with Flamsteed designations:

2 Dra 5.19; 3 Dra 5.32; 4 Dra 5.01; 6 Dra 4.95; 7 Dra 5.43; 8 Dra 5.23; 9 Dra 5.37; 16 Dra 5.53; 17 Dra – 5.07, 6.53; 20 Dra 6.40; 26 Dra 5.23; 29 Dra 6.61; 30 Dra 5.02; 34 Dra 5.43; 35 Dra 5.02; 36 Dra 4.99; 37 Dra 5.96; 38 Dra 6.79; 40 Dra 6.11; 41 Dra 5.74; 42 Dra 4.82; 48 Dra 5.67; 49 Dra 5.51; 50 Dra 5.37; 51 Dra 5.40; 53 Dra 5.13; 54 Dra 5.00; 55 Dra 6.26; 59 Dra 5.11; 65 Dra 6.27; 66 Dra 5.40; 68 Dra 5.70; 69 Dra 6.20; 71 Dra 5.71; 73 Dra 5.18; 74 Dra 5.96; 75 Dra 5.38; 76 Dra 5.75; 77 Dra 5.91; 78 Dra 5.18; 205 Dra 7.29

Other notable stars: