Your Guide to the Solar System and the Night Sky
This site is free and ad-free thanks to the support of our users. If you can, please consider a donation.
public Observing fromLocation: Greenwich, United Kingdom edit_location_alt
north SunriseRise: 6:47  
clear_day Transit: 12:50  
SunsetSet: 18:52 south
sunny DaytimeWhat's Visible Now
All Constellations » Eridanus » 

τ4 Eridani (tau4 Eridani)

Altitude: -53.9°   Azimuth: 44.7°   Direction: North-East

τ4 Eridani is a variable and multiple giant star in the constellation of Eridanus.

τ4 Eridani visual magnitude is 3.69. Because of its moderate brightness, τ4 Eridani 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 τ4 Eridani:


τ4 Eridani (tau4 Eridani) is below the horizon from Greenwich, United Kingdom edit_location_alt.

Altitude: -53.9°
Azimuth: 44.7°
Direction: North-East

Celestial coordinates and finder chart of τ4 Eridani

τ4 Eridani 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 τ4 Eridani are provided in the following table:

03h 19m 31s
-21° 45’ 28”

The simplified sky map below shows the position of τ4 Eridani in the sky:

Finder chart τ4 Eridani (tau4 Eridani) star
Simplified finder chart for τ4 Eridani (tau4 Eridani).

Visibility of τ4 Eridani 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 τ4 Eridani (tau4 Eridani) 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: 111.8°
Max altitude: 16.8°
Azimuth: 248.2°

Digitized Sky Survey image of τ4 Eridani

The image below is a photograph of τ4 Eridani 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 τ4 Eridani is 0.052 arcsec per year in Right Ascension and 0.033 arcsec per year in Declination and the associated displacement for the next 10000 years is represented with the red arrow.

Image of τ4 Eridani (tau4 Eridani) star
DSS2 image of τ4 Eridani. The red arrow shows the motion of τ4 Eridani during the next 10000 years (8.67 arcmin in Right Ascension and 5.50 arcmin in declination);

Distance of τ4 Eridani from the Sun and relative movement

τ4 Eridani is distant 258.12 light years from the Sun and it is moving far from the Sun at the speed of 42 kilometers per second.

79.18 pc
258.12 ly
42 km/s
0.052 arcsec/year
0.033 arcsec/year

Spectral properties of τ4 Eridani

τ4 Eridani belongs to spectral class M3 and has a luminosity class of III corresponding to a giant star.


The red dot in the diagram below shows where τ4 Eridani is situated in the Hertzsprung–Russell diagram.

HR Diagram
H-R diagram showing the position of τ4 Eridani. Attribution: Richard Powell / CC BY-SA

τ4 Eridani star system properties

τ4 Eridani 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 τ4 Eridani double sysyem:

5.5 arcsec

Alternative designations of τ4 Eridani

τ4 Eridani
(tau4 Eridani)