Menu

Rho Leonis — Star in Leo

Magnitude 3.9m Star Leo Visible
Star Map
+ List + Plan

Observe

1Physical Properties

Magnitude 3.85
Range 3.83 - 3.90
Period 3.4 days
Variable Type ACYG
Spectral Type B1.5Ib supergiant
Star Color Blue-white (B-V -0.14)
Distance 5,436 ly

2Position & Identifiers

RA 10h 32m 48.7s
Dec +09° 18' 24.0"
Constellation Leo
HR 4133
HIP 51624
HD 91316
SAO 118355
Bayer Rho
Flamsteed 47 Leo
Variable ID Rho Leo
SIMBAD

3How easy to spot?

Sign in and configure your equipment and default location to see a personalized row.
Equipment Bortle 3 Bortle 4 Bortle 5
Naked eye Easy Medium+ Medium+
50mm finder Easy Easy Easy
150mm scope Easy Easy Easy
Easy Medium Hard Very hard Impossible

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

4Visibility

Set a location in User Settings to see visibility data.

Best season Jan – Mar (peak: Feb)

5Survey Image

Loading survey image…

Explore

7

Size Comparison

Querying VizieR for stellar data…
8

Compare Stars

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

Alpha Cyg 3.83 - 3.90V.
4.4, 4.8v, sep. 0.11"; combined mag., colors.
Inferred statistically by F. Schlesinger in 1915. Unresolved by speckle interferometry 1982.17.
Color excess E(B-V) = +0.08.
Lyman beta observed from COPERNICUS. Nitrogen enhanced, and carbon deficient.
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.

49 Leo
Medium+
Tight double — a rewarding split at 2.1″
Double Star mag 5.67 0.9° Leo
NGC 3332
Hard+
Elliptical galaxy
Galaxy mag 13.0 1.9° Leo
56 Leo
Hard+
Semi-regular variable, range 5.7–6.0
Variable Star mag 5.81 6.5° Leo
Show on Map

Explore Nightbase

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

Arthur Eddington
1919 eclipse expedition confirming general relativity; first theory of stellar interiors; the Eddington limit
Biography
The Life of Stars
From birth in a nebula to spectacular death — how stars are born, shine, swell, and die, and how to read the clues in their starlight.
Article
Leo
Mythology, bright stars, and deep-sky highlights.
Constellation
}