Dolphin (constellation)
Dolphin constellation |
|
---|---|
Latin name | Delphinus |
Latin genitive | Delphini |
Abbreviation | Del |
Right ascension | 20 h 14 m 14 s to 21 h 08 m 00 s |
declination | + 2 ° 24 ′ 08 ″ to + 20 ° 56 ′ 24 ″ |
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 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 |
---|---|---|---|---|---|
β | 6th | Rotanev | 3.63 | 100 | F5 III + F2 IV |
α | 9 | Sualocin | 3.77 | 250 | B9 IV |
γ | 12 | 3.87 | 125 | K1 IV + F7 V | |
ε | 2 | Deneb Dulfim | 4.03 | 330 | B6 III |
δ | 11 | 4.42 (var) | 220 | kA7hF0mF0 IV-V | |
ζ | 4th | 4.65 | 220 | A3 V | |
ρ | Rho Aquilae | 4.95 | 150 | A2 V | |
κ | 7th | 5.05 (var) | 98 | G2 IV | |
17th | 5.18 | 480 | K0 III | ||
η | 3 | 5.38 (var) | 240 | A3 IVs | |
ι | 5 | 5.42 | 190 | A1 IV | |
18th | 5.51 | 245 | G6 III | ||
16 | 5.54 | 200 | A5 V | ||
13 | 5.56 | 430 | A0 V | ||
HR 8044 | 5.70 (var) | 520 | M3 III | ||
θ | 8th | 5.71 | 2,000 | K3 Ib | |
HR 7774 | 5.94 | 260 | A5m | ||
HR 7899 | 5.98 | 1,300 | B3 V | ||
15th | 5.99 | 100 | F5 V | ||
10 | 6.00 (var) | 500 | K4 III | ||
1 | 6.08 | 750 | A1 III | ||
14th | 6.32 | 500 | A1 Vs | ||
HD 196885 | 6.39 | 109 | F8 IV: + M1 V | ||
HD 195019 | 6.97 | 123 | G1 V + K3: | ||
WASP-2 | 11.98 (var) | 470 | K1 V + M | ||
HR (Nova Delphini 1967) | 12.4 (var) | 3,000 | |||
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
- Richard Wagner : Dolphin 2 . In: Paulys Realencyclopadie der classischen Antiquity Science (RE). Volume IV, 2, Stuttgart 1901, Col. 2509 f.
Web links
Individual evidence
- ↑ esky - Job's Coffin
- ^ Günther Bendt: Constellation Dolphin. In: Astronomie.de. Retrieved August 22, 2019 .