Dolphin (constellation)

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Dolphin constellation
Delphinus constellation map.png
Legend
Latin name Delphinus
Latin genitive Delphini
Abbreviation Del
Right ascension 20141420 h 14 m 14 s to  21 h 08 m 00 s210800
declination 2022408+ 2 ° 24 ′ 08 ″ to  + 20 ° 56 ′ 24 ″2205624
surface 188,549 deg²
rank 69
Completely visible 90 ° N to 69.5 ° S
Observation time for Central Europe March - January
Number of stars brighter than 3 mag 0
Brightest star (size) Rotanev (3.63)
Meteor streams

no

Neighboring constellations
(
clockwise from north )
swell IAU ,

The dolphin (also Delfin , Latin Delphinus ) is a constellation near the celestial equator .

description

The constellation eagle as seen on autumn evenings in the southwest
Animation with fade-in of the constellation eagle (Aquila) with its main star Altair, the constellations dolphin and arrow (Sagitta) as well as the summer Milky Way, recorded in the star park Westhavelland in the southern star sky.

The dolphin stands northwest of the bright star Altair in the eagle (Aquila) and can therefore be easily found. It is a small but memorable summer constellation and, because of its location on the celestial equator, can be seen from all over the inhabited world. In the dolphin, the stars Sualocin , Rotanev , Delta and Gamma Delphini form a diamond-shaped constellation, which is called "Job's Coffin" in English.

history

The dolphin is one of the classic 48 constellations of antiquity mentioned by Ptolemy .

The names alpha delphini and Rotanev for the brightest stars to go to the Italian astronomer Niccolo Cacciatore back, the successor of Giuseppe Piazzi at the observatory of Palermo . If you read the star names backwards, "Nicolaus Venator" is a Latin form of Cacciatores name. He added the names to a star catalog in 1814 and in this way immortalized himself twice in the sky. So far he was the only astronomer who managed to do this.

mythology

There are two versions of the mythological origin:

The sea god Poseidon freed the nereid Amphitrite . Since she did not want to lose her virginity, she fled to the Atlas Mountains . Poseidon then sent out several scouts, including a certain Delphinos. He eventually stumbled upon Amphitrite and persuaded her to agree to the wedding. In gratitude, the god of the sea moved the image of a dolphin to the sky.

The second version is about the Greek singer Arion of Lesbos , who served at the court of Periander , the ruler of Corinth . Arion became rich on a trip to Italy and Sicily . On the way home from Taranto , the crew of his ship conspired against him to take the treasure. With death in sight, Arion made one last request: he wanted to sing a lament. The crew granted him this. But while Arion was singing, he jumped overboard and was rescued by a dolphin who was infatuated with the music. The dolphin dropped Arion on the coast of Greece and disappeared.

Celestial objects

Stars

B. F. Names or other designations size Lj Spectral class
102β 6th Rotanev 3.63 100 F5 III + F2 IV
101α 9 Sualocin 3.77 250 B9 IV
103γ 12 3.87 125 K1 IV + F7 V
105ε 2 Deneb Dulfim 4.03 330 B6 III
104δ 11 4.42 (var) 220 kA7hF0mF0 IV-V
106ζ 4th 4.65 220 A3 V
117ρ Rho Aquilae 4.95 150 A2 V
110κ 7th 5.05 (var) 98 G2 IV
400 17th 5.18 480 K0 III
107η 3 5.38 (var) 240 A3 IVs
109ι 5 5.42 190 A1 IV
400 18th 5.51 245 G6 III
400 16 5.54 200 A5 V
400 13 5.56 430 A0 V
400 HR 8044 5.70 (var) 520 M3 III
108θ 8th 5.71 2,000 K3 Ib
400 HR 7774 5.94 260 A5m
400 HR 7899 5.98 1,300 B3 V
400 15th 5.99 100 F5 V
400 10 6.00 (var) 500 K4 III
400 1 6.08 750 A1 III
400 14th 6.32 500 A1 Vs
400 HD 196885 6.39 109 F8 IV: + M1 V
400 HD 195019 6.97 123 G1 V + K3:
400 WASP-2 11.98 (var) 470 K1 V + M
400 HR (Nova Delphini 1967) 12.4 (var) 3,000
400 V1339 (Nova Delphini 2013) 16.9 (var) 14,000

Double stars

system Sizes (mag) distance
α 3.9 / 6.4 0.2 ″
β 4.0 / 4.9 0.3 ″
γ 4.3 / 5.1 9.0 ″
1 6.2 / 8.0 0.9 ″
13 5.6 / 8.6 1.5 ″
16 5.6 / 11.8 34.4 ″
18th 5.6 / 9.9 197.5 ″
NGC 6933 10.6 / 11.6 29.3 ″

Sualocin (α Delphini) is a binary star system about 250 light years away. The single stars orbit each other once every 17 years. With an angular distance of only 0.2 ″, they cannot be separated by amateur astronomers.

The star system Rotanev (Beta Delphini) has an orbital period of 26.7 years and consists of a giant star with 1.75 solar masses and a subgiant with 1.5 solar masses. The stars are 4.0 mag and 4.9 mag bright and are currently 0.3 ″ apart. The distance is therefore too small for a separation with an amateur telescope. They will reach the maximum mutual angular distance of 0.6 ″ around the year 2030. Rotanev is 100 light years from the Sun.

γ Delphini is the most beautiful double star in the dolphin because of its color contrast. Next to the 4.3 mag bright, yellowish-orange glowing main star γ 2 Delphini (spectral type K1 IV) is at a distance of 9.0 ″ its 5.1 mag bright, white companion γ 1 Delphini (spectral type F7 V). The orbital period is approximately 3,250 years. Even a small telescope with an aperture of 5 cm separates this double star from 30 to 40 times magnification. γ Delphini is 125 light years away from us.

A double star that is far apart, but only optical, is 18 Delphini . This one has a planet , namely 18 Delphini b .

Spectroscopic binary stars in dolphins are (the period in brackets): δ Delphini (40.58 days), ι Delphini (11.04 days) and 14 Delphini (10.88 days).

For NGC 6933 see section: Messier and NGC objects .

Variable stars

star Size (mag) period Type
δ 4.4 to 4.5 0.1568 days δ Scuti star
R. 7.6 to 13.8 285.5 days Mira star

R Delphini is a variable star of the Mira type that changes its brightness significantly over a period of 285.5 days.

In the past few decades, two novas have appeared in the dolphin that could be seen with the naked eye: the Nova Delphini 1967 (HR Delphini) in December 1967 and the Nova Delphini 2013 (V339 Delphini) in August 2013.

NGC objects

NGC other data-sort-type = "number" | size Type Surname
6891 10.5 planetary nebula
6905 10.9 planetary nebula Blue Flash Nebula
6933 10.2 optical double star
6934 8.9 Globular clusters
7006 10.6 Globular clusters

NGC 6905 is a 10.9 mag planetary nebula. It is nicknamed the Blue Flash Nebula because it appears bluish-turquoise in photographs. Its distance is only roughly known and is estimated to be 7,000 light years.

The brightest deep sky object in the dolphin is the globular cluster NGC 6934 . This is about 50,000 light years away and has an apparent magnitude of 8.9 mag. It is visible as a foggy spot with a telescope or telescope from an opening of 7 cm. Single stars at the edge are recognizable from an opening of 25 cm.

NGC 6933 is a faint optical double star whose components 10.6 mag and 11.6 mag are bright and have an angular distance of 29.3 ". Since the discoverer Herman Schultz mistakenly believed he recognized a faint nebula around this double star, it was included in the New General Catalog .

With a distance of 135,000 light years, NGC 7006 is one of the most distant globular star clusters in the Milky Way. To observe it, you need a medium-sized telescope with an opening of 15 cm or more.

See also

literature

Web links

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

Individual evidence

  1. esky - Job's Coffin
  2. ^ Günther Bendt: Constellation Dolphin. In: Astronomie.de. Retrieved August 22, 2019 .