Pi Centauri — Double Star in Centaurus

Magnitude 3.9^m DoubleStar Centaurus (Cen) Visible

Star Map + List + Plan

Observe

1Physical Properties

Magnitude 3.89

Spectral Type B5V

Star Color Blue (B-V -0.15)

Distance 357 ly

2Position & Identifiers

RA 11h 21m 00.4s

Dec -54° 29' 28.0"

Constellation Centaurus (Cen)

HR 4390

HIP 55425

HD 98718

SAO 238986

Bayer Pi

3How easy to split?

Primary 3.9 mag Companion 5.7 mag Separation 0.4″

Sign in and configure your equipment and default location to see a personalized row.

Telescope	Bortle 3	Bortle 4	Bortle 5
80 mm refractor 80mm refr.	V. hard	V. hard	V. hard
150 mm Newton 150mm Newt.	V. hard	V. hard	V. hard
Celestron C8 (203 mm SCT) C8 203mm	V. hard+	V. hard+	V. hard+

Easy Medium Hard Very hard Impossible

Bortle 3 = rural · 4 = outer suburbs · 5 = suburbs

To reach "Medium" at Bortle 3, you'd need at least a 540 mm reflector.

4Visibility

Set a location in User Settings to see visibility data.

Best season Feb – Apr (peak: Mar)

5Multiple Star System

Separation 0.4″

Companion Mag 5.7

Position Angle 120°

Star Colors A: Blue B: White

Discoverer I 879

Notes

4.3 B5VN, 5.0 B6V, 39.18y, a = 0.277". Combined mag., colors.

Separation over time

Period: 39.0 y Eccentricity: 0.853 Now: 0.41", PA 124° + 0.01" in 5 years

Apparent separation over time, computed from ORB6 orbital elements. Steep curves indicate fast-changing pairs — catch them while they're splittable.

Eyepiece View

Telescope Eyepiece

Log in to set your own equipment

80x Dawes: 1.9″ TFOV: 0.6°

Seeing

Scale Realistic = true angular size

A: 3.9 · B: 5.7 · Sep: 0.4″ · PA: 120° · N up, E right

Unresolved · Rayleigh: 2.3″ · Dawes: 1.9″ · Eff: 2.3″

Explore

7

Size Comparison

Querying VizieR for stellar data…

8

Compare Stars

Compare with another star

9

Spectral Classification

10

Hertzsprung-Russell Diagram

Loading HR diagram…

Read: The Hertzsprung-Russell Diagram — Reading Stars Like a Map

11

Stellar Lifecycle

12

Blackbody Spectrum

13

Stellar Absorption Spectrum

Simulated absorption spectrum based on spectral type. Hover over lines to identify elements.

14

Stellar Fusion

Discover

15Stellar Notes

Group/Cluster

Sco-Cen assoc.

16

Light Travel Time Machine

17

Relativistic Travel

Nearby in the Sky

Other targets within a few degrees — pan your scope a little and keep exploring.

Visibility scores assume a 150 mm Newton at Bortle 4.

Barred spiral galaxy

Galaxy mag 11.81 4.0° Centaurus

Open Cluster mag 8.3 4.4° Centaurus

Small bright planetary nebula

Planetary Nebula mag 8.0 4.9° Centaurus

Tight double — a rewarding split at 2.3″

Double Star mag 2.69 7.3° Vela

Explore Nightbase

Related knowledge, tools, and stories — no observation planning required.

Double Stars — A Guide for Observers

Two suns where one appeared — how to find, split, and appreciate the night sky's finest pairs. From Albireo's gold-and-blue to the Sirius B challenge.

Mythology, bright stars, and deep-sky highlights.

Phases, transits, and the brightest planet in the sky.

}