When is the best time to observe Suhail al Muhlif?

Suhail al Muhlif is best observed from December through February, with peak visibility during January when it transits around midnight in the Northern Hemisphere.

Where is Suhail al Muhlif located in the sky?

Suhail al Muhlif lies in the constellation Vela at right ascension 08h 10m and declination -47° 20′.

What telescope do I need to split Suhail al Muhlif?

Splitting Suhail al Muhlif requires an aperture of roughly 60 mm or larger — the components are separated by about 41.2″ at magnitudes near 1.8. Larger apertures and steady seeing help resolve the pair cleanly.

Suhail al Muhlif — Double Star in Vela

HIP 39953; Gamma2 Velorum

Observable Double Star Excellent (64/100)

Sep: 41.2", Companion: mag 4.1

Wolf-Rayet

Late-stage massive star with a dense stellar wind; radius is taken from published spectral models rather than estimated from spectral class.

Read: Wolf-Rayet Stars — The Shortest, Fiercest Lives in the Galaxy

Magnitude 1.6–1.8^m DoubleStar Vela (Vel) Visible

Star Map + List + Plan

About Suhail al Muhlif

Description

Regor (also called Suhail al Muhlif) is one of the most remarkable star systems visible to the naked eye at magnitude 1.78. The primary is a Wolf-Rayet star (spectral type WC8) in a binary with an O9 supergiant, located about 1,100 light-years away. Wolf-Rayet stars are extremely hot, massive stars that are blowing off their outer layers in powerful stellar winds at thousands of km/s, exposing their helium-burning cores.

Observing Tips

Gamma Vel lies in the rich Milky Way fields of Vela and is one of the finest wide double stars in the sky — a small telescope reveals a brilliant pair of blue-white stars separated by about 41 arcseconds. The surrounding star field is gorgeous in binoculars. Visible from the southern hemisphere and low northern latitudes. Best observed February through May.

History

The informal name Regor (Roger spelled backwards) was a joke by Apollo 1 astronaut Gus Grissom, honoring crewmate Roger Chaffee. The name stuck in some usage. Gamma Vel was one of the first Wolf-Rayet stars identified, and its extreme spectral features have made it a prototype for studying massive stellar evolution.

Fun Facts

The Wolf-Rayet component of Gamma Vel is losing mass at an extraordinary rate — shedding roughly one Earth mass per year through its fierce stellar wind. This wind collides with the O-star companion's wind, creating a cone of shocked, superheated gas that emits X-rays. The star is a supernova candidate.

Observe

1Physical Properties

Magnitude 1.78

Range 1.81 - 1.87

Period 79 days

Variable Type Wolf-Rayet Variable

Spectral Type WC 8 Wolf-Rayet

Late-stage massive star with a dense stellar wind; radius is taken from published spectral models rather than estimated from spectral class.

Star Color Blue (B-V -0.22)

Radius 6.0 R☉

Distance 1,257 ly

2Position & Identifiers

RA 08h 09m 32.0s

Dec -47° 20' 12.0"

Constellation Vela (Vel)

HR 3207

HIP 39953

HD 68273

SAO 219504

Bayer Gamma2

Variable ID Gam2 Vel

SIMBAD Wikipedia

3How easy to split?

Primary 1.8 mag Companion 4.1 mag Separation 41.2″

Telescope	Bortle 3	Bortle 4	Bortle 5
80 mm refractor 80mm refr.	Easy	Easy	Easy
150 mm Newton 150mm Newt.	Easy	Easy	Easy
Celestron C8 (203 mm SCT) C8 203mm	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 Dec – Feb (peak: Jan)

5Light Curve

6Multiple Star System Quintuple

Components 5 (quintuple)

Component IDs AB

Separation 41.2″

Companion Mag 4.1

Companion Sp O9I

Position Angle 221°

Star Colors A: Blue B: Blue

Discoverer DUN 65

Notes

See HR 3206. Mag. and colors blended with other companions. C = CoD -46d3848, 7.65V, B6V at 63", physical. D, 9.07V, | Am at 94", SB, over 7d?, optical.

Separation over time

Measured 1826 → 2017 (191 y)

Separation drift 42.9" → 41.2" (-1.70")

Rate -0.0089" / y

PA drift 222° → 221° (-1°, -0.005°/y)

Slow change over generations — observable in lifetime comparisons.

Measured from the WDS observational archive. No orbital solution has been derived — most likely the period is too long to fit an orbit to the available measurement arc.

Eyepiece View

Telescope Eyepiece

80x Dawes: 1.9″ TFOV: 0.6°

Seeing

Scale Realistic = true angular size

A: 1.8 · B: 4.1 · Sep: 41.2″ · PA: 221° · N up, E right

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

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Size Comparison

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Spectral Classification

Hertzsprung-Russell Diagram

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

Stellar Lifecycle

Blackbody Spectrum

Stellar Absorption Spectrum

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

Stellar Fusion

Discover

16Stellar Notes

Variable Star

1.6 - 1.8V, 154 sec. Sp. var. in about 200 sec. Variability too great to be explained by the 78.5d SB companion. | Possibly a third close companion: a collapsed star of less than 2 solar masses.

Spectroscopic Binary

Comp. A of visual double, 78.5d, K 43.1k/s, V0 -18.0k/s, asini 45.8. Alternate orbit 78.5002d, K 70k/s, | V0 +12k/s, msin3i 32, asini 67. Possible mass transfer from WR to O-type component.

Group/Cluster

Gamma Velorum group which includes HR 3206, probably also HD 68157 at 20' and HR 3213 at 36' from A; HII region.

Spectral

Magnesium and iron depleted by factor of 100 relative to the sun. UV spectrum dominated by supergiant companions. The | Wolf-Rayet component appears to be the most massive known. Radio emission indicates a circumstellar gas cloud extending | beyond the orbit of the binary. Also classified WC8+O7.5e.

Alternative Names

Suhail al Muhlif; Al Suhail al Muhlif; "Spectral Gem of Southern Skies".

Remarks

Diam. = 0.00043 - 0.00044".