τ2 Aquarii (tau2 Aquarii)

τ2 Aquarii is a variable and double hypergiant star in the constellation of Aquarius.

τ2 Aquarii visual magnitude is 4.01. Because of its moderate brightness, τ2 Aquarii 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 τ2 Aquarii:

Color of τ2 Aquarii ⬤

Magnitude of τ2 Aquarii 4.01

Class Hypergiant

VISIBILITY RIGHT NOW τ2 Aquarii (tau2 Aquarii) is above the horizon from Greenwich, United Kingdom [change]. Altitude: 6°.

Celestial coordinates and finder chart of τ2 Aquarii

τ2 Aquarii 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 τ2 Aquarii are provided in the following table:

Right Ascension J2000 22h 49m 35s

Declination J2000 -13° 35’ 32”

Galactic Longitude 52.27°

Galactic Latitude -58.52°

Constellation Aquarius

The simplified sky map below shows the position of τ2 Aquarii in the sky:

Finder chart τ2 Aquarii (tau2 Aquarii) star

Simplified finder chart for τ2 Aquarii (tau2 Aquarii).

Visibility of τ2 Aquarii from your location

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

Today's τ2 Aquarii (tau2 Aquarii) rise, transit and set times from Greenwich, United Kingdom [change] are the following (all times relative to the local timezone Europe/London):

Azimuth: 103.6° RISE 6:23

Max altitude: 24.9° TRANSIT 11:11

Azimuth: 256.4° SET 15:59

RIGHT NOW τ2 Aquarii (tau2 Aquarii) is above the horizon from Greenwich, United Kingdom

Digitized Sky Survey image of τ2 Aquarii

The image below is a photograph of τ2 Aquarii 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 τ2 Aquarii is -0.012 arcsec per year in Right Ascension and -0.038 arcsec per year in Declination and the associated displacement for the next 10000 years is represented with the red arrow.

DSS2 image of τ2 Aquarii. The red arrow shows the motion of τ2 Aquarii during the next 10000 years (-2.00 arcmin in Right Ascension and -6.33 arcmin in declination);

Distance of τ2 Aquarii from the Sun and relative movement

τ2 Aquarii is distant 379.95 light years from the Sun and it is moving far from the Sun at the speed of 1 kilometers per second.

Distance (parsec) 116.55 pc

Distance (light year) 379.95 ly

Heliocentric radial velocity 1 km/s

Proper Motion RA -0.012 arcsec/year

Proper Motion Dec -0.038 arcsec/year

Spectral properties of τ2 Aquarii

τ2 Aquarii belongs to spectral class M0 and has a luminosity class of III corresponding to a hypergiant star.

Absolute magnitude -1.32

Spectral Type M0III

Color Index (B-V) 1.57

Temperature of τ2 Aquarii 3691K

The red dot in the diagram below shows where τ2 Aquarii is situated in the Hertzsprung–Russell diagram.

H-R diagram showing the position of τ2 Aquarii. Attribution: Richard Powell / CC BY-SA

τ2 Aquarii star system properties

τ2 Aquarii is a visual double star which can be observed with the help of small or medium telescopes. The table below shows key information about the τ2 Aquarii double sysyem:

Main star magnitude 4.01

Secondary star magnitude 8.51

Magnitude difference 4.5

Separation 132.5 arcsec

Alternative designations of τ2 Aquarii

Bayer designation τ2 Aquarii
(tau2 Aquarii)

Flamsteed designation 71 Aquarii

Henry Draper Catalogue HD216032

SAO Catalogue SAO165321

Hipparcos Catalogue HIP112716

Durchmusterung Catalogue BD-14 6354

FK5 Catalogue 861

General Catalogue of Variable Stars 14329

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Other stars in Aquarius