| Nearby
Double Star System
HR 8086, HD 201092, PPM 86049, HIP 104217, NSV 13546, TYC 03168-2798 1, GSC 03168-2798 Visual Magnitudes: 5.2 + 6 Apparent Separation: 30.5" Minimum requirements to view: any telescope under urban skies |
This multiple star system is among the most interesting in the sky. A mere 11 light years distant, the stars of 61 Cygni are among our closest neighbors. The primary (A) is a cool K5 main sequence star that is suspected to be variable (from 5.19 to 5.27 magnitude). The B component is a cool K7 dwarf that is also suspected of variability (a tiny variation from 6.02 to 6.09 magnitude). The orbit for these stars is indeterminate, but an orbital period of at least 700 years is indicated.
61 Cygni lies to the southeast of Deneb. Look for a triangle of stars of similar brightness. 61 Cyg is the westernmost. North is up and east is left.Currently these stars are 30.5" apart, making them easy in any scope. The cool surface temperatures give them a ruddy orange hue that really makes them stand out in the field. The fainter star is a slightly darker red-orange. These stars are near enough to us that their motion relative to the sun is visible in just a few short years. When you look at this ruddy pair in the eyepiece imagine them drifting to the northeast against the stationary background stars.
The view in a 6" at 135x. The first image represents the appearance in August 2000. The second is how things will appear in August 2005. North is down and east is to the right.
It is a testament
to how how much fainter the low-mass stars such as these are that
the components of 61 Cygni appear so much fainter than stars of similar
distance such as Sirius (-1.5 magnitude) and Procyon (0.4 magnitude). The
low mass stars are also cooler which gives them a distinct reddish hue.
The masses of the 61 Cygni stars are around 1/2 that of the sun and produce
1/6 as much light. Sirius, on the other hand, has a mass around 2.5 times
that of our sun and is 40 times brighter. A star with 40 times the mass
of the sun is a whopping 500,000 times brighter! Such massive stars are
of the O spectral type and are very hot, giving them a distinct blue hue.
The massive stars start
out with much more fuel to burn, but they burn it so fast that they live
very short lives. The components of 61 Cygni will be around for tens of
billions of years--long after Sirius and our sun are gone. As such, this
pair of stars will be drifting across the sky long after our sky is gone...
| Millennium
Star Atlas Vol III Chart 1146
Sky Atlas 2000 Chart 9 Uranometria 2000 Vol I Chart 121 |
