τ Boötis (tau Boötis)

Above the horizon. Rise: 13:21 | Tran: 20:51 | Set: 4:25

Alt: 16.64° Az: 277.11° Direction: West

τ Boötis is a variable and double sub-giant star of spectral class F6 in the constellation of Boötes.

τ Boötis visual magnitude is 4.5. Because of its moderate brightness, τ Boötis is easily visible to the naked eye from locations with dark skies, while it might be barely visible, or not visible at all, from light-polluted skies.

DSS2 image of τ Boötis. The red arrow shows the motion of τ Boötis during the next 1000 years (-8.03 arcmin in Right Ascension and 0.68 arcmin in declination);

Celestial Coordinates

Apparent

Right Ascension 13h 48m 29s

Declination +17° 19’ 49”

Hour Angle 05h 39m 25s

Sidereal Time 19h 27m 54s

J2000

Right Ascension 13h 47m 15s

Declination +17° 27’ 24”

Galactic Coordinates

Galactic Longitude 358.95°

Galactic Latitude 73.88°

Finder Chart

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Finder chart for τ Boötis (tau Boötis).

Magnitude, Color, Spectral Class

Color ⬤

Magnitude 4.5

Class Sub-giant

Absolute magnitude 3.53

Spectral Type F6IV

Color Index (B-V) 0.48

Temperature 6481K

The red dot in the diagram below shows where τ Boötis is situated in the Hertzsprung–Russell diagram.

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

Star System Properties

τ Boötis 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 τ Boötis double sysyem:

Main star magnitude 4.5

Secondary star magnitude 12

Magnitude difference 7.5

Separation 5 arcsec

Distance, Radial Speed, Proper Motion

τ Boötis is distant 50.84 light years from the Sun and it is moving towards the Sun at the speed of 16 kilometers per second.

Distance (parsec) 15.60

Distance (light year) 50.84

Radial Speed -16 km/s

Proper Motion RA -0.482 arcsec/y

Proper Motion Dec 0.041"/y

Alternative Designations

Bayer designation τ Boötis
(tau Boötis)

Flamsteed designation 4 Boötis

Henry Draper Catalogue HD120136

SAO Catalogue SAO100706

Hipparcos Catalogue HIP67275

Durchmusterung Catalogue BD+18 2782

Gliese Catalogue Gl 527 A

FK5 Catalogue 507

General Catalogue of Variable Stars 6444

Aitken Double Star Catalogue ADS9025

Visibility from Your Location

Today's τ Boötis (tau Boötis) rise, transit and set times from Greenwich, UK are the following (all times relative to the local timezone Europe/London):

Azimuth: 72.7° RISE 13:21

Max altitude: 55.9° TRANSIT 20:51

Azimuth: 287.3° SET 4:25

Set Location

Other stars in Boötes