21 Aquilae

21 Aquilae is a variable and double bright giant star in the constellation of Aquila.

21 Aquilae visual magnitude is 5.15. Because of its reltive faintness, 21 Aquilae should be visible only from locations with dark skyes, while it is not visible at all from skyes affected by light pollution.

The table below summarizes the key facts about 21 Aquilae:

Color of 21 Aquilae ⬤

Magnitude of 21 Aquilae 5.15

Class Bright giant

VISIBILITY RIGHT NOW 21 Aquilae is below the horizon from Greenwich, United Kingdom edit_location_alt.

Celestial coordinates and finder chart of 21 Aquilae

21 Aquilae is situated close to the celestial equator, as such, it is at least partly visible from both hemispheres in certain times of the year. Celestial coordinates for the J2000 equinox as well as galactic coordinates of 21 Aquilae are provided in the following table:

Right Ascension J2000 19h 13m 42s

Declination J2000 +02° 17’ 36”

Galactic Longitude 37.52°

Galactic Latitude -3.9°

Constellation Aquila

The simplified sky map below shows the position of 21 Aquilae in the sky:

Simplified finder chart for 21 Aquilae.

Visibility of 21 Aquilae from your location

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

Today's 21 Aquilae rise, transit and set times from Greenwich, United Kingdom edit_location_alt are the following (all times relative to the local timezone Europe/London):

Azimuth: 87.7° RISE 21:34

Max altitude: 40.8° TRANSIT 3:48

Azimuth: 272.3° SET 9:57

RIGHT NOW 21 Aquilae is below the horizon from Greenwich, United Kingdom

Digitized Sky Survey image of 21 Aquilae

The image below is a photograph of 21 Aquilae 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 21 Aquilae is 0.009 arcsec per year in Right Ascension and -0.003 arcsec per year in Declination and the associated displacement for the next 100000 years is represented with the red arrow.

DSS2 image of 21 Aquilae. The red arrow shows the motion of 21 Aquilae during the next 100000 years (15.00 arcmin in Right Ascension and -5.00 arcmin in declination);

Distance of 21 Aquilae from the Sun and relative movement

21 Aquilae is distant 640.47 light years from the Sun and it is moving towards the Sun at the speed of 5 kilometers per second.

Distance (parsec) 196.46 pc

Distance (light year) 640.47 ly

Heliocentric radial velocity -5 km/s

Proper Motion RA 0.009 arcsec/year

Proper Motion Dec -0.003 arcsec/year

Spectral properties of 21 Aquilae

21 Aquilae belongs to spectral class B8 and has a luminosity class of II corresponding to a bright giant star.

Absolute magnitude -1.32

Spectral Type B8II

Color Index (B-V) -0.07

Temperature of 21 Aquilae 11092K

The red dot in the diagram below shows where 21 Aquilae is situated in the Hertzsprung–Russell diagram.

H-R diagram showing the position of 21 Aquilae. Attribution: Richard Powell / CC BY-SA

21 Aquilae star system properties

21 Aquilae 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 21 Aquilae double sysyem:

Main star magnitude 5.15

Secondary star magnitude 12.65

Magnitude difference 7.5

Separation 36.2 arcsec

Alternative designations of 21 Aquilae

Flamsteed designation 21 Aquilae

Henry Draper Catalogue HD179761

SAO Catalogue SAO124408

Hipparcos Catalogue HIP94477

Durchmusterung Catalogue BD+02 3824

FK5 Catalogue 3537

General Catalogue of Variable Stars V1288 Aql

Aitken Double Star Catalogue ADS12182

In Evidence

Other stars in Aquila