Episode 308 – Northern Stars You Should Know With Dave Chapman Show Notes

months.

Stars You Should Know

(Dave Chapman, 2023)

Coming up: 

Spring (May)

Summer (July)

Fall (September)

South Polar (November)

Focussing on classic Greek-Roman names with occasional indigenous references. The classic names are used in some GoTo telescope software for sky alignment (e.g. Sky-Watcher SynScan and Celestron).

Spectral classes O B A F G K M — Annie Jump Cannon

Stars You Should Know—North Polar

About 12 bright stars —from 2^nd to 4^th magnitude (OK to find, even in the city)

—4 are used for celestial navigation (58 in all)  

—the first 9 are Sky-Watcher SynScan and  Celestron alignment stars

Starting with Ursa Major—usually identified as the Big Dipper

—useful in finding the North Star (Polaris)

Consult a simple north polar star chart with Polaris in the centre.

URSA MAJOR (UMa) “Great Bear”

First 2 stars are the pointer stars, Dubhe & Merak

Dubhe – alpha UMa “Back of the Bear” 

– mag. 1.8, variable multiple star, K0 orange, classic navigation star

– with the other three “bowl” stars of the Big Dipper, represents the she-bear Muin 

– Muin and the Seven Bird Hunters (Mi’kmaq sky story)

Merak – beta UMa “Loins of the Bear”

– mag 2.3, variable star, A0 white

– Merak and Dubhe are The Pointers, about 5 degrees apart

Mizar – zeta Uma “Horse and Rider” (with Alcor)

– Middle star in handle

– mag. 2.2, multiple star, A1 white

– famous vision test for Roman soldiers, 12 minutes of arc apart

– Chickadee and birchbark pot in the Muin story

More info on the Mi’kmaw sky story Muin and Seven Bird Hunters: tinyrl.com/4akte5cy 

URSA MINOR (UMi) “Small Bear”

Polaris – alpha UMi “North Star” 

– use Ursa Major The Pointers Merak & Dubhe to find Polaris (Merak—>Dubhe, 6 times the  distance)

 – mag. 2.0, delta Cepheid variable double star, F7 yellow-orange, classic navigation                 star 

– NOT the brightest star in the sky (#49 on p. 283 of the Handbook)

– brightest star within 30 degrees of the north celestial pole 

– is getting brighter and its variability is decreasing

Kochab –    beta Umi the “Guardians of the Pole” with Pherkad (not IAU) (Like Merak &  Thuban of Umi)

• mag. 2.1, variable double star, K4 orange giant, classic navigation star
• 500 times more luminous than Sun, 50 times bigger

CASSIOPEIA (Cas) “Queen of (Ancient) Ethiopia”

Follow a line from Mizar through Polaris and beyond to find the W shape.

Schedar – alpha Cas “Breast”

• mag. 2.2, multiple  star, K0 orange, classic navigation star

Caph – beta Cas “Stained Hand”

• mag. 2.3, variable double star, F2 yellow-white giant
• varies 6% in brightness over 2.5 hour period

Navi – gamma Cas (not IAU)

• reverse spelling of “Ivan,” middle name of astronaut Gus Grissom
• mag. 2.2, variable double star, B0 blue-white
• Be star—rapidly rotating, 150x the Sun

DRACO (Dra) “Dragon” (guarded the Golden Fleece)

Eltanin – gamma Dra “Serpent” or “Dragon”

• mag. 2.2, double star, K5 orange-red, classic navigation star (brightest in Draco)
• moving towards Earth, may be brightest star in sky in 1.5 million years

Thuban – alpha Dra “Dragon’s Tail”

• midway between Mizar and Kochab
• mag. 3.7, variable double star, A0 white giant—may have been brighter
• was pole star when Egyptians built pyramids

CEPHEUS (Cep) “King of (Ancient) Ethiopia”

delta Cep – no name (not bright enough?)

• mag. 3.5, delta Cepheid variable/double star, F5–G2 yellow supergiant
• Henrietta Swan Leavitt discover the yardstick of the heavens: regular period correlated with absolute magnitude
• Led to determining the distance to M31 and unlocking one of the greatest mysteries of the universe

mu Cep – Herschel’s “Garnet Star” (not IAU)

• mag. 3.4–5.1 variable double star, M2 supergiant
• multiple star system of 6 components
• very large (out to Jupiter/Saturn distance) very luminous, abs. mag. -7

only dim because of large distance ~2400 light years

• mu Cepheid irregular variable, like Betelgeuse, will probably become supernova 
• deep red colour in telescope 

References:

Star Tales (2018) Ian Ridpath

Star Names (1963) Richard Hinckley Allen

Sky Safari 7 Pro (star lore by Jim Kaler)

A Concise Dictionary of Astronomy (1991) Jacqueline MItton

RASC Observer’s Handbook (2023)