#astronomy Attempting to find vibrant double and triple stars within the constellation of Cassiopeia – Astronomy Now

December 14, 2019 - Comment

The immediately recognisable five-star M-shaped sample of stars representing the primary physique of the constellation Cassiopeia (pronounced kas-ee-uh-pee-uh) lies virtually overhead within the north round 7pm GMT as seen from the British Isles through the Christmas interval. Because the constellation lies in opposition to the wealthy stellar backdrop of the Milky Means, Cassiopeia comprises a number


The immediately recognisable five-star M-shaped sample of stars representing the primary physique of the constellation Cassiopeia (pronounced kas-ee-uh-pee-uh) lies virtually overhead within the north round 7pm GMT as seen from the British Isles through the Christmas interval. Because the constellation lies in opposition to the wealthy stellar backdrop of the Milky Means, Cassiopeia comprises a number of fantastic double and a number of stars for small telescopes, labelled right here in inexperienced and described beneath. For scale, beta (β) to epsilon (ε) Cassiopeiae is about one-and-a-half spans of a fist at arm’s size. Click on on the graphic to obtain a printable model in PDF format. AN graphic by Ade Ashford.Eager Northern Hemisphere stargazers will rejoice that the winter solstice, which happens on 22 December 2019, brings the longest nights of the 12 months. That is the time when observers within the UK have twelve nighttimes – moonlight however – to get pleasure from beginning at 6pm GMT. When you relish an early night stargaze earlier than it will get too chilly, one readily identifiable constellation that lies nearly overhead at 7pm GMT through the festive season as seen from the British Isles is Cassiopeia (pronounced kas-ee-uh-pee-uh).

Most individuals study to determine Cassiopeia as a five-star M-shaped (in case you are dealing with north and searching virtually overhead presently of 12 months) sample of second- and third-magnitude stars that may simply be encompassed by the span of an outstretched hand at arm’s size. When you have been one of many fortunate ones who acquired a brand new telescope for Christmas, why not search out a few of the constellation’s stunning double and a number of stars set in opposition to the wealthy backdrop of the Milky Means.

AN graphic by Ade Ashford.Sigma (σ) Cassiopeiae
α = 23h 59.0m, δ = +55° 45’ (J2000.zero)
Magnitudes: +5.zero & +7.1
Separation: three.1 arcseconds

Sigma (σ) Cassiopeiae is a detailed double star for 10-cm (Four-inch) aperture telescopes and bigger. An evening of regular seeing and a magnification of round 150× is required to see this pairing of a magnitude +5.zero major and magnitude +7.1 companion separated by three.1 arcseconds. Search for bluish-white and yellow tints. Sigma Cassiopeiae is about 1,500 light-years distant. And right here’s one other truth: owing to precession, Sigma Cassiopeiae has a imply proper ascension of precisely (give or take a second) of 00h 00m 00s on the present J2019.9 epoch!

AN graphic by Ade Ashford.Eta (η) Cassiopeiae, aka ‘Achird
α = 00h 49.1m, δ = +57° 49’ (J2000.zero)
Magnitudes: +three.Four & +7.5
Separation: 13.Four arcseconds

Generally often known as Achird, Eta (η) Cassiopeiae is a fantastic double star with noticeable colors first recognised as a binary system by William Herschel in the summertime of 1779. A straightforward pair for small telescopes at 50× owing to the huge 13.Four arcsecond separation, its magnitude +three.Four major is yellow, whereas the magnitude +7.5 companion is orange. The orbital interval of Eta Cassiopeiae is about 500 years and its distance from Earth is 19.Four light-years.

AN graphic by Ade Ashford.Σ 163 (Cassiopeia)
α = 01h 51.3m, δ = +64° 51’ (J2000.zero)
Magnitudes: +6.eight & +eight.eight
Separation: 34.eight arcseconds

A vibrant double in Cassiopeia that doesn’t require excessive magnifications to resolve is Struve 163 – continuously appreviated to Σ 163 in catalogues – on account of its huge, 34.eight arcsecond separation. A small telescope at 30 to 50× magnification is all that’s required to view the magnitude +6.eight orange major and its magnitude +eight.eight bluish companion. The celebrities lie about 2600 light-years from the Solar.

AN graphic by Ade Ashford.Iota (ι) Cassiopeiae
α = 02h 29.1m, δ = +67° 24’ (J2000.zero)
Magnitudes: +Four.6, +6.9 & +eight.Four
Separation: 2.6 & 7.6 arcseconds

We will conclude this very transient tour of the perfect double and a number of stars Cassiopeia has to supply with what I think about to be the best triple star in the whole sky. Iota (ι) Cassiopeiae can be a a number of star whose parts typify the refined and subjective nature of star colors. Whereas many understand simply three white stars, a big proportion of observers see a pure white major, the nearer companion as yellow-orange and the broader companion as bluish-white. Your notion of star colors can even fluctuate with the kind of telescope and eyepiece used. What do you see? Nonetheless you interpret its element hues, you’ll need an evening of fine seeing and usually a 10-cm (Four-inch) aperture ‘scope at round 150×, or extra. Iota Cassiopeiae lies about 133 light-years distant.

Cassiopeia actually and delusion
Cassiopeia is an historic constellation, one of many authentic 48 listed by Greek astronomer and mathematician Ptolemy (circa 100-170 AD). On the temperate northern latitudes of the British Isles, it’s circumpolar – completely above the horizon, by no means rising or setting. By dimension, Cassiopeia is the 25th largest out of the 88 constellations recognised in the present day.

In Greek mythology, Cassiopeia is queen to King Cepheus and mom of Andromeda. Cassiopeia angered the ocean god Poseidon by boasting that Andromeda was extra stunning than sea nymphs often known as the Nereids. As punishment, Poseidon decreed that Andromeda needs to be sacrificed to the ocean monster Cetus (however she was rescued by Perseus), whereas Cassiopeia was condemned to eternally revolve across the north celestial pole seated on her throne.



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