Swan (constellation)
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Constellation swan |
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| Latin name | Cygnus |
| Latin genitive | Cygni |
| Abbreviation | Cyg |
| Right ascension | 19 h 07 m 30 s to 22 h 03 m 03 s |
| declination | + 27 ° 43 ′ 57 ″ to + 61 ° 21 ′ 28 ″ |
| surface | 803,983 deg² rank 16 |
| Completely visible | 90 ° N to 29.1 ° S |
| Observation time for Central Europe | summer |
| Number of stars brighter than 3 mag | 5 |
| Brightest star (size) | Deneb (1.25) |
| Meteor streams | |
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Neighboring constellations ( clockwise from north ) |
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| swell | IAU , |
The swan ( Latin / technical language Cygnus ) is a constellation in the northern sky .
description
The swan, with its eagle and lyre, is one of the most striking summer constellations , but due to its northern position it can still be seen in autumn and on early winter evenings. Its two bright rows of stars form a striking cross in the sky, which is why it is also known as the Northern Cross or Northern Cross (counterpart to the Southern Cross ).
The constellation is supposed to represent a flying swan , with the brightest star α Cygni ( Deneb ) symbolizing the broad tail feathers, while the stars η and β ( Albireo ) form the long neck stretched out in flight. In the central star γ Cygni ( Sadr ), the widely spread wings begin (the inner parts of which correspond to the crossbar of the cross). Both wings are slightly bent backwards, as it corresponds to the actual flight image.
Deneb is the north-eastern corner of the large summer triangle that it forms with the stars Vega in the lyre and Altair in the eagle .
The bright band of the Milky Way runs through the swan , which is why the constellation is rich in special stars and foggy objects. If you sweep back and forth with your eyes or binoculars , you can see the structures of the Milky Way and their division south to the eagle. The multiple alternation between extremely star-rich and dark areas as well as several bright star clusters is interesting .
The second strongest cosmic radio source in the sky is located in the constellation . The radio emission is of an active galaxy emitted the name Cygnus A received. The galaxy is 650 million light years away and only becomes visible on long-exposure telescope images.
The swan also houses the cosmic X-ray source Cygnus X-1 . Its X-rays come from a binary star 8200 light years away . The main star has a small but very massive companion that appears to have turned into a black hole . Gas from the shell of the main star flows over it at high speed, with extremely high temperatures occurring due to friction and X-rays being released.
history
The swan is one of the 48 constellations of ancient Greek astronomy , which were already described by Claudius Ptolemy .
On the star 61 Cygni , the astronomer Friedrich Wilhelm Bessel succeeded for the first time in 1838 in measuring the distance to a star precisely using parallax . At only 11.4 light years away, 61 Cygni is one of the closest neighbors to our sun .
mythology
The swan ( Latin Cygnus ) is a large, conspicuous constellation north of the celestial equator and can be seen in the summer and autumn skies . In Greek mythology , the swan embodied the god Zeus , who in this figure stalked young women without being recognized.
Another interpretation connects it with the legend about the demigod Phaethon . Phaethon had borrowed his father Helios' sun chariot . However, in the high-spirited journey across the sky, the car got out of control and wreaked havoc that threatened to burn the world. To prevent a complete annihilation of the world and to punish the hubris of Phaeton, Zeus killed him with lightning and fell into the river Eridanus . Phaeton's friend Cyknos , the king of the Ligurians , was inconsolable over his death and wandered incessantly along the banks of the Eridanus. Finally he was lifted into the sky in the shape of the swan.
In Ovid is Cygnus as an ally of the Trojans in the Trojan War mentioned. With the sea god Neptune as father and a Nereid (water deity, daughter of Nereus ) as mother, he is invulnerable to weapons. Only when Achilles strangles him with his hands does he die. Neptune turns his dead body into a swan.
According to another interpretation, the constellations of the summer triangle ( eagle , lyre and swan) are the Stymphalic birds .
Meteor streams
From August 3rd to 25th every year the Kappa-Cygnids can be observed, the radians of which are at the star κ Cygni.
Celestial objects
Stars
| B. | F. | Names or other designations | size | Lj | Spectral class |
|---|---|---|---|---|---|
| α | 50 | Deneb | 1.25 m (var) | 2,000 | A2 Iae |
| γ | 37 | Sadr , Schedir | 2.23 m | 1,800 | F8 Iab |
| ε | 53 | Gienah | 2.48 m | 72.7 | K0 III |
| δ | 18th | Fawaris | 2.87 m | 165 | B9 III + F1 V |
| β | 6th | Albireo | 2.93 m | 430 | K3 II + B8: p + B8 Ve |
| ζ | 64 | 3.21 m | 143 | G8 III-IIIaBa0.5 + D | |
| ξ | 62 | 3.73 m | 800 | K5 Ib + A2 V | |
| τ | 65 | 3.73 m (var) | 66 | F2 IV + G0 V + M2.5 Ve | |
| ι 2 | 10 | 3.76 m | 121 | A5 V | |
| κ | 1 | 3.76 m | 124 | G9 III | |
| ο 1 | 31 | V695 | 3.80 m (var) | 900 | K4 Ib + B4 V + B9 |
| η | 21st | 3.88 m | 135 | K0 III | |
| ν | 58 | 3.94 m | 370 | A1 Vne | |
| ο 2 | 32 | V1488 | 3.98 m (var) | 1,100 | K5 Iab + B7 V |
| 41 | 4.01 m | 800 | F5 Ib-II | ||
| ρ | 73 | 4.02 m | 124 | G8 IIIFe0.5 | |
| π 2 | 81 | 4.18 m (var) | 1,100 | B3 III | |
| 52 | 4.23 m | 200 | K0 IIIa | ||
| σ | 67 | 4.24 m | 3,000 | B9 Iab | |
| χ | 4.24 m (var) | 600 | S6-9 / 1-2e | ||
| 33 | 4.27 m | 159 | A3 IV – Vn | ||
| υ | 66 | 4.42 m (var) | 600 | B2 Vne | |
| 39 | 4.44 m | 250 | K2.5 IIIFe0.5 | ||
| θ | 13 | 4.48 m | 59.8 | F3 V + M3 V + M2-3 | |
| μ | 78 | 4.50 m | 73 | F7 V + F3 V | |
| f 2 | 63 | 4.51 m | 1,000 | K4 Ib-IIa | |
| λ | 54 | 4.54 m (var) | 800 | B5 V | |
| 47 | V2125 | 4.64 m (var) | 900 | K6: Ib + B2.5: | |
| π 1 | 80 | Azelfafage | 4.66 m | 1,700 | B3 III |
| φ | 12 | 4.67 m | 270 | K0 III + K0 III | |
| 8th | 4.72 m | 900 | B3 IV | ||
| f 1 | 59 | V832 | 4.75 m (var) | 1,400 | B1.5 Vnne |
| 57 | 4.77 m | 530 | B5 V + B5 V | ||
| 61 | V1803 (Bessel star) | 4.79 m (var) | 11.4 | K5 V + K7 V | |
| P | 34 | 4.82 m (var) | 6,000 | B1-2 Ia-0ep | |
| 30th | 4.82 m | 600 | A5 IIIn | ||
| 55 | V1661 | 4.86 m (var) | 2,700 | B4 Ia | |
| 15th | 4.89 m | 290 | G8 III | ||
| 72 | 4.91 m | 230 | K0.5 IIIFe0.5 + M5 | ||
| ψ | 24 | 4.92 m | 280 | A4 Vn + F4 | |
| b 2 | 28 | V1624 | 4.93 m (var) | 1,000 | B2.5 Ve |
| T | 4.93 m (var) | 440 | K3 III | ||
| ω 1 | 45 | V2021 | 4.94 m (var) | 900 | B2.5 IV |
| HR 7633 | 4.96 m | 900 | K4.5 IIIa | ||
| 22nd | 4.97 m | 1,400 | B5 IV | ||
| 17th | 4.97 m | 69 | F5.5 IV-V + K6 V: + K5 V + K5 V | ||
| 2 | 4.98 m | 800 | B3 IV | ||
| b 3 | 29 | V1644 | 4.99 m (var) | 139 | A2 V |
| A. | 68 | V1809 | 5.00 m (var) | 3,000 | O7.5 IIIn ((f)) |
| d | 20th | 5.03 m | 202 | K3 IIICN2 | |
| 74 | 5.04 m | 210 | A3 Vn | ||
| e | 26th | 5.05 m | 430 | G8 III | |
| 56 | 5.05 m | 134 | A6 V | ||
| HR 7495 | 5.06 m | 162 | F5 II-III | ||
| 75 | 5.09 m | 400 | M1 IIIab | ||
| 19th | V1509 | 5.12 m (var) | 700 | M2 III | |
| 23 | 5.13 m | 600 | B5 V | ||
| 4th | V1741 | 5.15 m (var) | 700 | B8pSi (FeII) | |
| 35 | 5.16 m | 3,000 | F6 Ib + B6.5 | ||
| HR 7468 | 5.17 m | 132 | G8.5 IIIbFe0.5 | ||
| 25th | V1746 | 5.19 m (var) | 1,300 | B3 IVe | |
| G | 71 | 5.22 m | 220 | K0 III | |
| HR 7759 | 5.24 m | 1,500 | K3 IIIaFe1 | ||
| 70 | 5.29 m | 1,300 | B3 V | ||
| HR 8216 | 5.31 m | 410 | A4 VpSiCrHg | ||
| c | 16 | 5.32 m | 69 | G1.5 Vb + G3 + MV | |
| HR 7444 | 5.34 m | 580 | A2 V | ||
| b 1 | 27 | V2008 | 5.36 m (var) | 78 | G8.5 Va |
| W. | 5.38 m (var) | 600 | M4-6 IIIe | ||
| 14th | 5.40 m | 700 | B9 III | ||
| 51 | 5.40 m | 1,300 | B2 V | ||
| 9 | 5.41 m | 600 | G8 III + A2 III: | ||
| 60 | V1931 | 5.43 m (var) | 1,500 | B1 Ve | |
| ω 2 | 46 | 5.44 m | 400 | M2 III | |
| HR 7628 | 5.46 m | 1,100 | B5 V | ||
| HR 8003 | 5.46 m | 1,000 | K0 II | ||
| HR 8005 | 5.47 m | 600 | K5 III | ||
| HR 7640 | 5.50 m | 470 | B9 Vn | ||
| 49 | 5.51 m | 800 | G8 IIb | ||
| HR 8306 | 5.51 m | 600 | M2 IIIbCa1 | ||
| HR 7427 | 5.54 m | 460 | K1 III | ||
| HR 8035 | 5.55 m | 260 | K0 III: Fe0.5 | ||
| HR 7969 | 5.56 m | 600 | K5 III | ||
| HR 7798 | 5.57 m | 410 | K0 IIIv | ||
| 36 | 5.58 m | 200 | A2 V | ||
| V1942 | 5.60 m (var) | 500 | A0 IV | ||
| HR 8040 | 5.60 m | 1,100 | B7 Vn + B7 V | ||
| HR 8208 | 5.60 m | 109 | F0 V | ||
| 40 | 5.62 m | 270 | A3 V | ||
| HR 7589 | 5.63 m | 4,000 | O9.5 Iab | ||
| V2140 | 5.64 m (var) | 6,000 | B8 Iae | ||
| V1768 | 5.65 m (var) | 5,000 | B1.5 Ia + | ||
| HR 7926 | 5.66 m | 1,100 | B8 II-III | ||
| HR 7904 | 5.67 m | 350 | K2 III | ||
| HR 8185 | 5.67 m | 330 | K0 III | ||
| V380 | 5.68 m (var) | 3,200 | B1.1 III + B2.5-3 V: | ||
| V389 | 5.69 m (var) | 380 | B9 V | ||
| 79 | 5.70 m | 270 | A0 V | ||
| HR 7743 | 5.70 m | 320 | G8 III | ||
| HR 7451 | 5.70 m | 82 | F7 V | ||
| 777 | 5.71 m | 52 | G7 IV-V + M4.5 V | ||
| 43 | V2121 | 5.72 m (var) | 123 | F0 V: | |
| 77 | 5.73 m | 410 | A0 V + A0 V + F2 V | ||
| HR 8161 | 5.74 m | 550 | B6 V | ||
| HR 8220 | 5.74 m | 150 | F0 V + M3.5 | ||
| ι 1 | 7th | 5.75 m | 350 | A1 V | |
| HR 8106 | 5.75 m | 440 | B9 III | ||
| HR 7781 | 5.76 m | 300 | A2 IV + F3 V | ||
| HR 8246 | 5.76 m | 490 | A0 V | ||
| V2015 | 5.78 m (var) | 430 | B8pSi | ||
| HR 7606 | 5.78 m | 1,200 | G1 Ib-IICH2Fe1 | ||
| HR 8403 | 5.78 m | 1,000 | B5 III | ||
| DT | 5.82 m (var) | 2,000 | F7 II | ||
| HR 7543 | 5.82 m | 470 | B8 Vn | ||
| HR 8025 | 5.82 m | 170 | F0 III | ||
| HR 7767 | 5.84 m | 2,400 | O8.5 III + B2.5 V + O9 Vnn + B1.5 V | ||
| HR 7514 | 5.84 m | 600 | M0 III | ||
| V460 (DS Pegasi) | 5.84 m (var) | 2,000 | C6.3 | ||
| HR 7697 | 5.85 m | 119 | F5 V | ||
| HR 7756 | 5.86 m | 112 | F5 V: | ||
| V1143 | 5.88 m (var) | 133 | F5 V + F5 V | ||
| V1334 | 5.88 m (var) | 2,300 | F1 II + B 7.0V | ||
| V1762 | 5.89 m (var) | 230 | K1 IV | ||
| V2119 | 5.90 m (var) | 1,400 | B2 Vne | ||
| 42 | 5.90 m | 3,000 | A2 Iab-Ib | ||
| HR 7591 | 5.90 m | 1,700 | B2 III | ||
| HR 7843 | 5.91 m | 900 | B8.5V | ||
| HR 8026 | 5.91 m | 800 | G8 II-III | ||
| HR 8078 | 5.92 m | 370 | K0 III | ||
| HR 7646 | 5.93 m | 450 | A5 III | ||
| HR 7502 | 5.93 m | 2,000 | A5 III | ||
| HR 7800 | 5.93 m | 800 | K7 III | ||
| 69 | V2157 | 5.94 m (var) | 8,000 | B0 Ib | |
| HR 8023 | 5.96 m | 4,000 | O6.5V ((f)) + B1-2V | ||
| V1743 | 5.96 m (var) | 1,300 | M 4.5 III | ||
| HR 7919 | 5.97 m | 450 | K2 III | ||
| HR 8218 | 5.99 m | 450 | B7 III | ||
| HR 8051 | 6.00 m | 600 | G5 III | ||
| HR 7322 | 6.00 m | 138 | F6I V: + M2.5V | ||
| 11 | 6.03 m | 600 | B8 Vne | ||
| 76 | 6.08 m | 500 | A2 V | ||
| 44 | 6.18 m | 3,000 | F5 Ib | ||
| 48 | 6.30 m | 900 | B8 IIIn | ||
| HD 197036 | 6.61 m | 1,200 | B5 IV | ||
| HD 185269 | 6.67 m | 170 | G2 V | ||
| HD 188753 | 7.43 m | 150 | G9 V | ||
| HD 187123 | 7.83 m | 160 | G5 V | ||
| Cygnus X-1 | 8.91 m (var) | 6,000 | O9.7 Iabpvar | ||
| HAT-P-7 | 10.48 m | 1,100 | F6 V | ||
| KY | 11.14 m (var) | 5,000 | M4 I | ||
| Kepler-22 | 11.7 m | 600 | G5 V | ||
| KIC 8462852 (Boyajian's star) | 11.88 m (var) | 1,400 | F3 V | ||
| Kepler-36 | 11.94 m | 1,500 | |||
| V1331 | 11.99 m (var) | 2,000 | F0 / F4-G5 | ||
| KIC 9832227 | 12.37 m (var) | 1,800 | G5 | ||
| Cyg OB2 # 12 | 12.54 m | 5,000 | B3-4 Ia + | ||
| Kepler-452 | 13.5 m | 1,400 | G2 | ||
| Kepler-33 | 13.7 m | 3,800 | |||
| Kepler-69 | 13.7 m | 2,700 | G4 V | ||
| Kepler-6 | 13.8 m | 1,600 | |||
| Kepler-11 | 14.2 m | 1,700 | G | ||
| Kepler-70 (KOI-55) | 14.9 m | 4,000 | sdB | ||
| Kepler-34 | 15.0 m (var) | 4,900 | |||
| Kepler-186 | 15.3 m (var) | 500 | M1 V | ||
| Kepler-35 | 15.8 m (var) | 5,400 | |||
| Kepler-47 | 15.8 m | 5,000 | |||
| Kepler-42 | 16.1 m | 130 | M4 V | ||
| Kepler-32 | 16.5 m (var) | 1,000 | M1 V | ||
| NML | 16.6 m (var) | 5,000 | M6 I | ||
| V1974 (Nova Cygni 1992) | 17 m (var) | 6,000 | |||
| V476 (Nova Cygni 1920) | 17.1 m (var) | ||||
| V1500 (Nova Cygni 1975) | 18 m (var) | 5,000 | |||
| V404 (Nova Cygni 1938 or 1989) | 19 m (var) | 8,000 | K0 IV | ||
| V1668 (Nova Cygni 1978) | 20 m (var) | 17,000 | |||
| Cygnus X-3 | 23,000 | WN4 / 5-6 / 7 | |||
| Kepler-1625 | 7,000 |
Deneb (α Cygni) is the brightest star in the swan with an apparent magnitude of 1.25 m . Its distance is not known exactly. Two independent distance determinations (both from 2008) resulted in values of 2,600 ± 200 and 1,550 ± 300 light years . It is a very luminous, bluish-white luminous supergiant of the spectral type A2 with 20 times the solar mass , 200 times the solar diameter and 200,000 times the solar luminosity . Its surface temperature is 8500 K . The name Deneb is an abbreviation of the Arabic name ḏanab al-daǧāǧa ("tail of the hen").
ε Cygni (Gienah, from Arabic ǧanāḥ "wing") is much closer with a distance of 73 light years. It is a yellowish glowing giant star belonging to the spectral class K0.
The star 61 Cygni has a certain importance in the history of astronomy as it was the first star to be able to measure distances. It was determined by Friedrich Wilhelm Bessel in 1838 to be 10.3 and a year later to be 9.3 light years (the modern value is 11.4 light years).
The section of the sky that was selected as a target area for the Kepler Space Telescope to search for extrasolar planets is mainly in the constellation Swan (the other two constellations are Lyra and Dragon ). As a result, many of the exoplanets discovered so far are in this constellation. Particularly interesting are the stars Kepler-11 , in which six planets were detected, and Kepler-22 , whose planet is in the habitable zone and could be an ocean planet .
Other stars or star systems in the swan of interest for research include the X-ray binary stars Cygnus X-1 and Cygnus X-3 , the hypergiant and LBV star P Cygni , the blue hypergiant Cyg OB2 # 12 , the red hypergiant NML Cygni and the abnormal variable star KIC 8462852 .
Double stars
| system | Sizes | distance |
|---|---|---|
| β | 3.2 m / 5.8 m / 5.1 m | 0.4 ″ / 34.6 ″ |
| δ | 2.9 m / 6.3 m | 2.7 ″ |
| ε | 2.5 m / 12.0 m / 14.7 m | 74.8 ″ / 93.4 ″ |
| λ | 4.7 m / 6.3 m | 1.1 ″ |
| μ | 4.7 m / 6.2 m | 1.5 ″ |
| ο 1 | 3.8 m / 7.0 m / 4.8 m | 108.6 ″ / 336.7 ″ |
| τ | 3.8 m / 6.6 m / 12.2 m / 13.8 m | 89.5 ″ / 1.0 ″ / 0.4 ″ |
| υ | 4.4 m / 10.8 m / 10.0 m | 15.2 "/ 22.1" |
| ψ | 5.0 m / 7.5 m | 2.8 ″ |
| ω 2 | 5.4 m / 6.6 m | 257 ″ |
| b 3 | 5.0 m / 6.6 m | 215.3 ″ |
| e | 5.2 m / 8.0 m | 41.6 ″ |
| 16 | 6.0 m / 13.0 m / 6.2 m | 3.2 ″ / 40.0 ″ |
| 17th | 5.0 m / 9.3 m / 8.5 m / 8.6 m | 792 ″ / 25.9 ″ / 3.0 ″ |
| 44 | 6.2 m / 9.0 m | 2.5 ″ |
| 48 | 6.4 m / 6.5 m | 182.7 ″ |
| 49 | 5.8 m / 8.1 m | 2.7 ″ |
| 52 | 4.3 m / 9.5 m | 6.6 ″ |
| 61 | 5.2 m / 6.0 m | 31.4 ″ |
| 77 | 6.3 m / 6.7 m / 8.1 m / 8.6 m | 159.1 ″ / 0.2 ″ / 0.4 ″ |
| 79 | 5.7 m / 11.1 m / 7.0 m | 1.8 ″ / 149.5 ″ |
Albireo (β Cygni) is a popular observation object because of the clear orange-blue color contrast of the individual stars and is therefore one of the most beautiful double stars in the summer sky . The angular distance between the main star β 1 Cygni (3.1 m , spectral type K2) and the companion star β 2 Cygni (5.1 m , spectral type B8) is 34.6 ″. A telescope with a 5 cm opening is sufficient for separation. On closer inspection, Albireo is a triple star , because β 1 Cygni is itself a narrow, subordinate double star. Its single stars are only 0.4 ″ apart; they are 3.2 m and 5.8 m bright (adding up the 3.1 m mentioned above ) and circle each other in 210 years. Between β 1 and β 2 Cygni, however, the orbital period is estimated to be at least 100,000 years. Some authors even assume that this is an optical double star . The name Albireo in use today goes back to a transmission error. The original Arabic name was al-minqar al-daǧāǧa ("the beak of the hen").
Other visually appealing “color contrast double stars” with orange and bluish components are ο 1 Cygni, ω 2 Cygni and b 3 (= 29) Cygni with distances of 337 ", 257" and 215 ". However, all three are clearly just optical double stars.
δ Cygni is a binary star system 165 light-years away with an orbital period of 920 years. The angular distance is 2.7 ″. In order to separate δ Cygni into two single stars, a telescope with a 10 cm aperture is required, whereby the separation is not very easy due to the great difference in brightness between the components.
τ Cygni is a physical four-fold system (probably even five-fold system) 66 light years away. It consists of two pairs of double stars 89.5 ″ apart, which in turn form a system of higher order. The components of the brighter system, a subgiant of the spectral type F2 with 3.8 m and a main sequence star of the spectral type G0 with 6.6 m , are 1.0 ″ apart and orbit each other in 49.6 years; the components of the weaker system, two red dwarfs , are 12.2 m and 13.8 m bright and are 0.4 ″ apart. Far away from this quadruple system (approx. 530 ″) is a star only 16 m bright, whose proper motion makes it very likely that it belongs to the τ-Cygni system.
Also a fourfold system, which is composed of two pairs of binary stars, is 17 Cygni, whereby the main systems with 792 ″ are very far apart. The distance and orbital period for the lighter system (5.0 m and 9.3 m ) are 25.9 ″ and 9,000 years and for the weaker system (8.5 m and 8.6 m ) 3.0 ″ and 230 years. The orbital period of the two systems to each other is extremely long at an estimated 1.1 million years. The 17 Cygni system is 69 light years away.
System 61 Cygni , 11.4 light years away, consists of two orange glowing main sequence stars that orbit each other once every 680 years. With a distance of 31.4 ″ it can be separated with a telescope with a 5 cm opening.
Spectroscopic binary stars in the swan are (the orbital period in brackets): ε Cygni (55 years), ζ Cygni (17.8 years, the companion is a white dwarf ), λ Cygni (11.7 years), ξ Cygni (18.5 Years), ο 1 Cygni (10.37 years), ο 2 Cygni (3.14 years), π 1 Cygni (26.33 days), π 2 Cygni (72.02 days), φ Cygni (434.17 days ), 4 Cygni (35.02 days), 9 Cygni (4.56 years), 22 Cygni (78.2 days), 35 Cygni (6.68 years), 39 Cygni (at 86 years one of the longest periods among the spectroscopic binary stars), 57 Cygni (2.85 days) and 60 Cygni (147 days).
Variable stars
| star | size | period | Type |
|---|---|---|---|
| α | 1.21 m to 1.29 m | α-Cygni star | |
| λ | 4.47 m to 4.54 m | Be star | |
| ο 1 | 3.7 m to 3.9 m | 3,784 days | ζ aurigae star |
| ο 2 | 3.9 m to 4.1 m | 1,147 days | ζ aurigae star |
| τ | 3.65 m to 3.75 m | δ Scuti star | |
| υ | 4.3 m to 4.5 m | γ-Cassiopeiae star | |
| χ | 3.3 m to 14.2 m | 409 days | Mira star |
| A. | 4.98 m to 5.09 m | ellipsoid variable | |
| P | 3 m to 6 m | bright blue changer | |
| b 1 | Amplitude = 0.05 m | RS Canum Venaticorum Star | |
| b 2 | 4.9 m to 5.0 m | 0.7 days | SX Arietis star |
| b 3 | 4.94 m to 4.97 m | 0.031 days | δ Scuti star |
| 4th | Amplitude = 0.02 m | α 2 -Canum Venaticorum star | |
| 19th | 5.1 m to 5.4 m | slowly irregularly changeable | |
| 47 | 4.7 m to 4.8 m | slowly irregularly changeable | |
| 55 | 4.8 m to 4.9 m | α-Cygni star | |
| 60 | 5.3 m to 5.5 m | Eclipsing variable and Be star | |
| 61 | 4.8 m to 4.9 m | BY-Draconis star / Flare star | |
| DT | 5.6 m to 6.0 m | 2.50 days | classic Cepheids |
| KIC 8462852 | 11.88 m (max.) | aperiodic drops in brightness |
Deneb (α Cygni) is the namesake of the α-Cygni stars , a subgroup of the pulsation-variable stars . The apparent brightness of Deneb varies between 1.21 m and 1.29 m and has no clear periodicity.
The star χ Cygni , 600 light years away, is a variable star of the Mira type . Stars of this type show strong fluctuations in brightness, although they are extraordinarily large even for a Mira star. At its maximum, χ Cygni has a brightness of 3.2 m and is clearly visible to the naked eye. At a minimum it sinks to 14.2 m ; in order to observe it then you need a larger telescope. The brightness fluctuations take place over a period of 409 days. χ Cygni lights up yellow-orange and belongs to the spectral class S.
The hypergiant P Cygni (34 Cygni) belongs to the rare group of bright blue variable stars (also called S-Doradus stars). The extremely massive and luminous star (approx. 30 solar masses and 600,000 times the luminosity of the sun) changes its brightness between 3 m and 6 m without any recognizable regularity . Its distance is 5,000 to 6,000 light years.
Both components of the double star 61 Cygni are variable. The main star is a BY Draconis star with 5.19 m at maximum and 5.27 m at minimum; with the companion, a flare star , the brightness fluctuates between 6.02 m and 6.09 m .
Of particular interest is the star KIC 8462852 , which is 1,400 light-years away - in and of itself an ordinary main sequence star of the spectral type F3, whose irregular drops in brightness puzzles astronomers. The star also received media attention when a Dyson swarm from an alien civilization was speculated as the cause. The most plausible reason for the fluctuations in brightness is an uneven dust ring that surrounds the star and blocks the light, but this explanation also leaves questions unanswered.
Messier and NGC objects
The Milky Way runs through the swan . Parallel to this, the “Great Rift” (literally “large crack”), a band of dust or dark clouds , runs to the south . In the swan, the Milky Way appears particularly bright and rich in stars. This is due to the position of the solar system in the Milky Way. It is located on the inside of the Orion arm , a spiral arm of the Milky Way. When looking towards the swan, our line of sight runs roughly the length of this arm; so we look “into” him. As a result, this area of the sky is rich in objects that are interesting for both research and amateur astronomy.
The open star cluster M 29 , 3,500 light years away, stands south of the bright star γ Cygni and can be easily found. A group of 20 to 30 individual stars can be seen in binoculars and a small telescope.
The open star cluster M 39 is about 1,100 light years away. A loose collection of 10 to 15 stars can be seen in binoculars and in the small telescope.
The planetary nebula NGC 6826 , 3,600 light years away , was discovered by Wilhelm Herschel in 1773 . In the telescope you can see a round, misty spot. The central star, a white dwarf, is one of the seemingly brightest central stars of a planetary nebula in the night sky at 10.6 m .
NGC 6914 is a group of three reflection nebulae with a north-south extension of about 15 arc minutes . The southern nebula is known as NGC 6914a (also vdB 131), the middle nebula as NGC 6914b (also vdB 132) and the northern nebula as NGC 6914c. On photographic recordings, the blue reflection nebulae appear in the midst of glowing red, surrounding H-II regions .
The Cygnus Arc or Cirrus Nebula is the remnant of a supernova explosion that occurred approximately 8,000 years ago. The entire supernova remnant is referred to as the Cygnus arc, while the Cirrus Nebula only refers to the visually visible part. This is divided into several parts. NGC 6960, also known as the Petrel Nebula, is the name of the 1 ° long nebula filament in the western part of the nebula that just passes the star 52 Cygni. NGC 6974 and NGC 6979 are two bright nodes in the northern part. In the eastern part is the “bone hand”, a 1 ° long, arched filament, consisting of NGC 6992 (northern part), NGC 6995 and IC 1340 (both southern part). If the sky is very dark, the extensive cirrus nebula can already be seen with binoculars. Interesting structures and filaments become visible with a telescope. It is best to use an interference filter such as a UHC or O-III filter for observation .
East of Deneb are the North American Nebula (NGC 7000), the Pelican Nebula (IC 5067 and IC 5070) and the dark cloud LND 935. All three objects also belong together physically and are part of the molecular cloud W 80, whereby LND 935 visually separates the North American Nebula from the Pelican Nebula . The North American Nebula got its name from its shape, which is reminiscent of a map of the North American continent. Despite its apparent brightness of 5 m , it is not easy to observe due to the low surface brightness . When observing with amateur instruments, a dark sky without light pollution is crucial, with a UHC or O-III filter making visibility much easier. The sighting in binoculars under excellent sky conditions is also reported. The part "Mexico" is a little brighter than the rest of the fog and easier to see. In the area of the North American nebula is the open star cluster NGC 6997 (often wrongly equated with NGC 6996). This contains 40 to 50 stars and is around 2,500 light years away. Whether it also belongs spatially to the nebula is questionable, especially since its distance is only vaguely known. The "Mexico part" and LND 935 represent the part of W 80 closest to the Sun with a distance of 2,000 light years, although this value is reasonably certain. In contrast to this, the distance of the “USA part”, in which NGC 6997 is located, is only roughly known and much greater - distance estimates are between 3,500 and 6,000 light years. Thus NGC 6997 appears to be a foreground object with no relation to the nebula.
NGC 7027 is a planetary nebula about 3,000 light-years away that was discovered in 1879. At only 600 years old, it is a very young planetary nebula. In the binoculars it is shaped like a star. At higher magnification in the telescope, an elongated nebula with a dark notch becomes visible.
In the constellation Swan there are two larger dark cloud regions, namely LND 906 ("Northern Coal Sack") south of Deneb and Le Gentil 3 halfway between the connecting line Deneb - Elephant Trunk Nebula . Both regions have a diameter of 5 ° to 6 ° and can be seen with the naked eye as “holes” in the bright band of the Milky Way when the sky is not polluted by light.
The swan houses a total of nine OB associations. These star associations usually occupy a section of the sky of several degrees of angle, which corresponds to a true size of many hundreds of light years. The member stars are formed from the same giant molecular cloud and are not gravitationally bound to one another. Of this, the association Cygnus OB2, 4,500 light years away, with 30,000 solar masses, is the most massive OB association in the swan and at the same time one of the most massive in the entire Milky Way. It includes 60 to 120 O stars, around 2,600 B stars and several thousand lighter stars. Many of them occur in close binary star systems. Also Cyg OB2 # 12 and NML Cygni , two of the currently largest and most massive stars known are also part of the association.
In the area of the swan cross lies the region Cygnus X (not to be confused with Cygnus X-1 ), a related complex of stars and molecular clouds with an angular extent of approx. 7 ° by 7 °. With a total mass of around 4 million solar masses, the region, 4,500 to 5,500 light years away, is one of the largest, most massive and most active star formation regions in the Milky Way. Observation is only possible in the radio and infrared range of the electromagnetic spectrum, as Cygnus X is mainly obscured in visible light by the upstream dark clouds of the Great Rift.
See also
Web links
- What is Cygnus X1? from the alpha-Centauri television series(approx. 15 minutes). First broadcast on June 23, 2004.
Individual evidence
- ↑ Rounded values. The exact distances are 802 ± 66 pc (Schiller, Przybilla, 2008, bibcode : 2008A & A ... 479..849S ) and 475 +90−75pc (Apellániz, Alfaro, Sota, 2008, bibcode : 2008arXiv0804.2553M ).