55 Cygni

55 Cygni is a variable and double supergiant star in the constellation of Cygnus.

55 Cygni visual magnitude is 4.84. Because of its moderate brightness, 55 Cygni should be easily visible from locations with dark skyes, while it can be barely visible, or not visible at all, from skyes affected by light pollution.

The table below summarizes the key facts about 55 Cygni:

Color of 55 Cygni ⬤

Magnitude of 55 Cygni 4.84

Class Supergiant

VISIBILITY RIGHT NOW 55 Cygni is above the horizon from Greenwich, United Kingdom edit_location_alt. Altitude: 19°.

Celestial coordinates and finder chart of 55 Cygni

55 Cygni is situated north of the celestial equator, as such, it is more easily visible from the northern hemisphere. Celestial coordinates for the J2000 equinox as well as galactic coordinates of 55 Cygni are provided in the following table:

Right Ascension J2000 20h 48m 56s

Declination J2000 +46° 06’ 51”

Galactic Longitude 85.75°

Galactic Latitude 1.49°

Constellation Cygnus

The simplified sky map below shows the position of 55 Cygni in the sky:

Simplified finder chart for 55 Cygni.

Visibility of 55 Cygni from your location

Location: Greenwich, United Kingdom edit_location_alt
Latitude: 51° 28’ 47” N
Longitude: 0° 00’ 00” E
Timezone: Europe/London

55 Cygni is circumpolar and transits at 04:15 UTC (altitude: 84.6°)

Digitized Sky Survey image of 55 Cygni

The image below is a photograph of 55 Cygni from the Digitized Sky Survey 2 (DSS2 - see the credits section) taken in the red channel. The area of sky represented in the image is 0.5x0.5 degrees (30x30 arcmins). The proper motion of 55 Cygni is 0.004 arcsec per year in Right Ascension and 0 arcsec per year in Declination and the associated displacement for the next 100000 years is represented with the red arrow.

DSS2 image of 55 Cygni. The red arrow shows the motion of 55 Cygni during the next 100000 years (6.67 arcmin in Right Ascension and 0.00 arcmin in declination);

Distance of 55 Cygni from the Sun and relative movement

55 Cygni is distant 2,248.28 light years from the Sun and it is moving towards the Sun at the speed of 7 kilometers per second.

Distance (parsec) 689.66 pc

Distance (light year) 2,248.28 ly

Heliocentric radial velocity -7 km/s

Proper Motion RA 0.004 arcsec/year

Spectral properties of 55 Cygni

55 Cygni belongs to spectral class B3 and has a luminosity class of I corresponding to a supergiant star.

Absolute magnitude -4.35

Spectral Type B3I

Color Index (B-V) 0.41

Temperature of 55 Cygni 6827K

The red dot in the diagram below shows where 55 Cygni is situated in the Hertzsprung–Russell diagram.

H-R diagram showing the position of 55 Cygni. Attribution: Richard Powell / CC BY-SA

55 Cygni star system properties

55 Cygni is a visual double star which can be observed only with the help of very large telescopes. The table below shows key information about the 55 Cygni double sysyem:

Main star magnitude 4.84

Secondary star magnitude 11.14

Magnitude difference 6.3

Separation 21.3 arcsec

Alternative designations of 55 Cygni

Flamsteed designation 55 Cygni

Henry Draper Catalogue HD198478

SAO Catalogue SAO50099

Hipparcos Catalogue HIP102724

Durchmusterung Catalogue BD+45 3291

General Catalogue of Variable Stars V1661 Cyg

Aitken Double Star Catalogue ADS14337

In Evidence

Other stars in Cygnus