Figure 1: A triple system of a red giant and a pair of yellow and white stars. The latter is very close and therefore can't be separated optically. Although it is the brightest star in Hercules, it doesn't appear very noticeable to us. Anyway in a good telescope you get a pretty picture.

Figure 2: The infrared image of the system showing how it is shrowded within its dust cloud extending up to ~90 AU.

Rasalgethi or Alpha Hercules

Introduction

Alpha Hercules is a triple stellar system, consisting of a heavy M=14 red, cool, and evolved M5Ib supergiant, and a binary system orbiting the primary. In this figure, you can see the apparent orbit of the secondary. To see the source website for the following figure click here, or for another interesting link here.
The list of photometric magnitudes of this system at different filters can be found on ADPS database. More interestingly can be the table of foreground galctic source along the sight to this star from 2MASS archive.
ISOInfrared spectra.

Constellation: Hercules
Distance: 382 light-years (117.23 pc)
Radial velocity: -33 km/sec
Space between Ras Algethi A and B: 550 AU
Orbit period of Ras Algethi A and B: 3600 years
Space between Ras Algethi Ba and Bb: 0.4 AU
Orbit period of Ras Algethi Ba and Bb: 51.578 days
Ras Algethi A
Spectral class: M5
Visual magnitude: 3.48
Luminosity: circa 17 000 * Sun
Mass: 7 - 8 * Sun
Diameter: 300 * Sun
Ras Algethi Ba
Spectral class: G5
Visual magnitude Ba and Bb: 5.39
Luminosity Ba and Bb: circa 140 * Sun
Mass: 4 * Sun
Ras Algethi Bb
Spectral class: F2
Mass: 2.5 * Sun

Light Curve in Johnson V and three other Wing filters.

Discrete Fourier Transform of the data in V filter. Note the identification of 8 individual modes above the 4-sigma significance limit, and also the Long-Secondary Period (LSP).

A code for stellar structure and evolution Cesam2k
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A collection of papers related to Cesam2k papers
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