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Suhail al Muhlif

HIP 39953; Gamma2 Vel

Observable Double Star Excellent (64/100)

Sep: 41.2", Companion: mag 4.1

HIP 39953; Gamma2 Vel DoubleStar Vel Visible Level 2 Small telescope (4") - Requires steady seeing
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Physical Properties

Magnitude 1.78
Range 1.81 - 1.87
Period 78.530 days
Variable Type Wolf-Rayet Variable
Spectral Type WC 8
Star Color Blue (B-V -0.22)
Distance 1256.8 ly

Position & Identifiers

RA 08h 09m 32.0s
Dec -47° 20' 12.0"
Constellation Vel
HR 3207
HIP 39953
Bayer Gamma2
Variable ID Gam2 Vel

Visibility

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Light Curve

Multiple Star System

Components 5
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

Eyepiece View

80x Dawes: 1.9″ TFOV: 0.6°
Realistic = true angular size
N E 221° A (1.8) B (4.1)

Sep: 41.2″ · PA: 221° · N up, E left

Resolved · Rayleigh: 2.3″ · Dawes: 1.9″ · Eff: 3.1″

Size Comparison

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Stellar Lifecycle

Spectral Classification

Hertzsprung-Russell Diagram

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Blackbody Spectrum

Stellar Absorption Spectrum

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

Stellar Notes

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.
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.
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.
Gamma Velorum group which includes HR 3206, probably also HD 68157 at 20' and HR 3213 at 36' from A; HII region.
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.
Suhail al Muhlif; Al Suhail al Muhlif; "Spectral Gem of Southern Skies".
Diam. = 0.00043 - 0.00044".

Survey Image

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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.