Podcaster: Shane and Chris
Title: Northern Stars You Should Know with Guest Dave Chapman
Organization: Actual Astronomy
Link : https://actualastronomy.podbean.com/
Description: The Actual Astronomy Podcast Presents Northern Stars You Should Know with Guest Dave Chapman. In this episode we have a conversation with our long time friend and amateur astronomer Dave Chapman. Focussing on classic Greek-Roman names with occasional indigenous references. The classic names are used in some GoTo telescope software for sky alignment. We discuss 12 Stars from Ursa Major, Ursa Minor, Cassiopeia, Draco and Cephus. Learn about the dipper pointer stars, The Guardians of the Pole, a star named after an Apollo astronaut and about the original Cepheid Variable.
Bio: Shane and Chris are amateur astronomers who enjoy teaching astronomy classes and performing outreach where they help the eyes of the public to telescope eyepieces.
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Transcript:
Episode 308 – Dave Chapman’s Northern Stars You Should Know
Intro: Dave Chapman’s Northern Stars You Should Know on Episode 308 of the Actual Astronomy Podcast. I’m Chris and joining me is Shane, we are amateur astronomers who love looking up at the night sky and this podcast is for anyone else who enjoys going out under the stars.
Welcome Back to the Show Dave!
First a big thank you to our Patreon Supporters! Denis and Daniel, we appreciate it. Also thanks to all our Patreon supporters and hey Dave who’s joining us today is one as well 🙂
As a bit of background Dave is a long time collaborator of mine, he’s been on the show a few times. He is a past editor of the RASC’s Observer’s Handbook, long time contributor to the RASC’s Journal. Most recently he collaborated with Cathy LeBlanc on the Mi’kmaq Moons: The Seasons in Mi’kma’ki but today he’s going to talk with us about some more stars we should all know…or know better. The last episode of Stars You Should Know holds the record for show downloads despite only being out 2 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 2nd to 4th 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)
Thanks for joining us today Dave!
And thanks to everyone for listening. We want your observations, sketches and photos of M51 for a soon to be announced show please send them to actualastronomy@gmail.com
End 308*
End of podcast:
365 Days of Astronomy
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