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Graffias

HIP 78820; Beta1 Sco; 8 Sco

HIP 78820; Beta1 Sco; 8 Sco DoubleStar Sco Visible Level 6 Professional/Research - Requires steady seeing
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Physical Properties

Magnitude 2.62
Spectral Type B1V
Star Color Blue-white (B-V -0.07)
Distance 399.7 ly

Position & Identifiers

RA 16h 05m 26.2s
Dec -19° 48' 20.0"
Constellation Sco
HR 5984
HIP 78820
Bayer Beta1
Flamsteed 8 Sco
Double Cat 9913

Visibility

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Multiple Star System

Components 5
Component IDs O
Separation 0.3″
Companion Mag 10.6
Position Angle 224°
Star Colors A: Blue-white B: Blue-white
Discoverer BU 947

Eyepiece View

80x Dawes: 1.9″ TFOV: 0.6°
Realistic = true angular size
N E 224° A (2.6) B (10.6)

Sep: 0.3″ · PA: 224° · N up, E left

Unresolved · 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

CPM with HR 5985 = ADS 9913C, at 14" and with B, 5.9v at 0.5", possibly SB. Lunar occultations and speckle | interferometry indicate companions 4.2v at 0.001" from A and 7.6v at 0.129" from C. Occultations by Jupiter and Io in | 1971 indicate complex system. Component C occulted by Io revealed the 2.5 mag. fainter companion at 0.1".
ADS 9913AD, 6.8281d, K 129.0k/s, V0 -1.0k/s, msin3i 16.0, asini 11.6. Mag. difference about 1v. Apsidal period | 51000 times orbital. Unresolved by speckle interferometry. Possible third SB component.
Sco OB2; Sco-Cen assoc.; probable member of Sco-Cen cluster; upper Sco region.
Ca and Na lines nearly stationary.
0.004".
Graffias; Grafias; Grassias; Acrab; Akrab; Elacrab.
From occult. by Jupiter, diam. Beta Sco A1 = 0.000422"; diam. Beta Sco A2 = 0.000264".

Survey Image

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About Graffias

Description

Graffias (also called Acrab) is a complex multiple star system at magnitude 2.62 in Scorpius, consisting of at least six stars. The primary is a blue giant of spectral type B1V. Located about 400 light-years from Earth, a small telescope reveals a double star with components separated by about 14 arcseconds.

Observing Tips

Graffias sits at the head of Scorpius, forming a line with Dschubba and Pi Sco. A small telescope splits it into a handsome double — a bright blue-white primary and a fainter companion. Best observed June through August when Scorpius is prominent.

History

The name Graffias comes from Greek/Latin roots meaning 'claws' or 'crab.' The alternate name Acrab comes from the Arabic 'al-'aqrab,' meaning 'the scorpion.' The multiple star nature has been gradually revealed over centuries of observation.

Fun Facts

Graffias is one of the most complex stellar systems visible in a small telescope — what appears as a simple double is actually six stars gravitationally bound together, revealed through spectroscopic and interferometric studies.