- 3523 - STARS - that are our Nearest Neighbors? The 8 nearest stars to us are less than 10 lightyears away. The closest is 4.2 lightyears away. Each star has a story to tell, and, learning about them makes finding these points of light in the sky much more interesting.
--------------------- 3523 - STARS - that are our Nearest Neighbors?
- One of the most disappointing things about backyard astronomy is that you use your telescope for the first time to look at the stars and all you see are points of light. Not very interesting! The planets are nice but the stars need some work. It involves knowledge and imagination.
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- As you learn about these astronomical objects you enjoy finding them in the night sky and then you enjoy your imagination visualizing what you are seeing is really like. I collect Hubble images for the same effect.
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- Ok, let’s find the nearest stars and see what our imagination should add to the discovery. First, let’s start with the brightest stars. The ones easiest to find but not necessarily the closest to us.
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--------------------------------------------------- Constellation ----------------------
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(1) ---------------- Sirius ------------------ Canis Major “ The Greater Dog”
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(2) ---------------- Canopus --------------- Carina “ The Keel”
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(3) ---------------- Alpha Centauri ------ Centaurus “ The Centaur”
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(4) ---------------- Arcturus --------------- Bootes “ The Bear Driver”
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(5) ---------------- Vega -------------------- Lyra “ The Harp”
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(6) ---------------- Capella ----------------- Auriga “ The Charioteer”
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(7) ---------------- Rigel -------------------- Orion “ The Hunter”
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(8) ---------------- Procyon ----------------- Canis Minor “ The Lesser Dog”
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(9) ---------------- Betegeuse --------------- Orion “ The Hunter”
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- It turns out that the Third Brightest Star is Alpha Centauri, which is actually three stars orbiting each other. Here is a list of the 8 closest stars. All are less than 10 lightyears away. None of the rest, except Sirius, makes the list as the brightest.
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- You can find the 100 closest stars, fortunately most of them can be found from the northern hemisphere.
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----------------------------------------------------------- Lightyears away ----------------------
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(1) ---------------- Proxima Centauri --------------------- 4.2
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(2) ---------------- Alpha Centauri A & B --------------- 4.4
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(3) ---------------- Bernard’s Star ------------------------- 6.0
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(4) ---------------- Wolf 359 ------------------------------- 7.8
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(5) ---------------- Lelande 21185 ------------------------- 8.3
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(6) ---------------- Sirius A and B ------------------------- 8.6
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(7) ---------------- UV and BL Ceti ----------------------- 8.7
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(8) ---------------- Ross 154 -------------------------------- 9.7
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(1) ---------------- Proxima Centauri --------------------- 4.2
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(2) ---------------- Alpha Centauri A & B --------------- 4.4 , actually Alpha Centauri is a triple star. the stars combined become the third brightest star in the sky. The separation between stars A and B varies between 2 arc seconds and 23 arc seconds. In year 2010, they are 7 arc seconds apart. Most telescopes can resolve 1 arc second, so, you should have no trouble splitting the pair.
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- The third star is Alpha Centauri C, known as Proxima Centauri, our closest star. It is only 4.24 lightyears away. However, it is so dim, only Magnitude 11.1, it is very difficult to make out with a backyard telescope.
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(3) ---------------- Bernard’s Star ------------------------- 6.0 lightyears away in the Constellation Ophiucus “ The Serpent Bearer” is the second closest system and the fastest star moving across the sky. Moving across the sky, 90 degrees to our line of sight, is called “proper motion”. Moving along our line of sight, toward us or away from us, is called “radial motion“.
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- Bernard’s Star is a Red Dwarf star with a Magnitude 9.5. It has a luminosity, (brightness), of only about 0.04% that of our Sun. It is very faint and a very old star, probably 12,000,000,000 years old. Our Sun in comparison is only 5,000,000,000 years old. In the past 50 years Barnard’s star has moved across the sky over 10 arc seconds, that is 1/3 the diameter of the Full Moon.
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(4) ---------------- Wolf 359 ------------------------------- 7.8 lightyears away. If you are a Star Trek fan you know that this was the star system where Mr. Spock was from, his home planet orbiting this star was Vulcan. This star is in the Constellation “Leo the Lion”. It is very faint, only Magnitude 13.4.
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- It has a mass that is 9% that of our Sun. That is barely enough mass to create nuclear fusion and to become a star. Mr Spock’s planet would have to orbit his star very close in order for Spock to stay warm.
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(5) ---------------- Lelande 21185 ------------------------- 8.3 lightyears away in the Constellation Ursa Major “ The Bear”. It is a Magnitude 7.5. Lelande is a star that is actually moving towards us, very unusual. In fact, in another 19,500 years it should be the third closest star, moving closer than Wolf 359 and Bernard’s Star at 4.60 lightyears away.
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- Skipping down to the 8th , 14th, and 15th closest stars:
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(8) ---------------- Ross 154 -------------------------------- 9.7 lightyears away in the
Constellation Sagittarius “The Archer”, or as I call it “ The Teapot”. This is a variable star. During an outburst its brightness increases by 4 Magnitudes. It is normally a Red Star at 10.4 Magnitude.
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- It is 17% the mass of our Sun and about 1,000,000,000 years old. It is rotating at 2.2 miles per hour. Our Sun also rotates very slowly taking about 25 days to complete one rotation. Of course, Earth takes one day and its surface is rotating at 1,000 miles per hour.
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(14) ---------------- 61 Cygni ------------------------- 11.4 lightyears away is a double star in the Constellation Cygnus “ The Swan”. It is a Magnitude 5.2 and Magnitude 6.0. This pair of stars at 11.4 lightyears away and were the first stars measured using parallax to determine their distance. This was first done in 1838.
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- As the Earth completes its orbit about the Sun each year our viewpoint changes by the diameter, 2 times 93 million miles, every 6 months. The parallax to nearby stars creates a shift in the angle to view the star against its distant background stars that do not shift.
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- This angle forms the tip of a triangle with a base of 186,000,000 miles. Using some geometry we can calculate the height of the triangle to be a distance of 67,000,000,000,000 miles, or 11.4 lightyears.
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(15) ----------------- LFT 1431-32 ------------------ 11.5 lightyears away in the Constellation Draco “ The Dragon”. It is another double star each shining in reddish light at Magnitude 8.9 and Magnitude 9.7. Their separation is 14 arc seconds so you telescope should easily split the pair. LFT stands for a proper motion of 0.5 arc seconds. That happens to be the astronomer’s abbreviation for stars having a proper motion of FT, five tenths of an arc second, 0.5 arc seconds.
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(27) ---------------- Kruger 60 -------------------------- 13.4 lightyears is another double star in the Constellation Cepheus “ The King of Ethiopia”. These are Red Dwarf stars shining at Magnitude 9.8 and Magnitude 11.4. The stars orbit each other in 44 years and the separation is only 2 to 3 arc seconds.
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- Those distances correspond to the distance between the Jun and Jupiter out to the distance between the Sun and Saturn. It is a good test for your telescope to see if you can resolve the pair. One of the pair is another Flare Star that has outbursts of light lasting 8 minutes, but, not at a regular occurrence. It is a doubling of brightness but consider yourself lucky if you happen to see it.
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(52) ---------------------- 70 Ophiuchi ------------------ 16.6 lightyears away. This is another double star that has a separation of 5 arc seconds. One star is yellow-orange of Magnitude 4.2. The other is Magnitude 6.1, only 17% as much light as its companion.
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(53) --------------------- Altair -------------------------- is the 53rd nearest star but the 12th brightest star of Magnitude 0.77 in the Constellation Aquila “ The Eagle”. Altair rotates very rapidly, a complete rotation ever 9 hours, our Sun takes 25 days for a complete rotation. Altair’s rapid rotation swells its equator by 20%.
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- Finding these nearest neighbor stars is an astronomer’s challenge. When you do find the right spot of light, or often, two spots of light, it helps to know the stories that fire the imagination.
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March 29, 2022 3523 - STARS - that are our Nearest Neighbors? 1236 3520
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--------------------- --- Tuesday, March 29, 2022 ---------------------------
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