The Stars on our Block

My nearest neighbor when I was growing up raised chickens in a coup and yard area surrounded by…yep, chicken wire. Beyond my nearest neighbor was the neighborhood, my block. It seemed immense when I was 8 years old, full of spaces to explore.

Our nearest neighbor star is Proxima Centauri, with its bigger sibling stars Alpha Centauri A and B. That family lives 4.25 – 4.35 light years away from us. That’s approximately 25,277,549,200,781 miles. So, you can see, our stellar neighborhood block is somewhat larger than my childhood block.

Proxima Centauri is a little star, a red dwarf about 1/7 the size of our Sun. Alpha A is a yellow G2-type dwarf and a little bigger, with Alpha B an orange K-type dwarf, a little smaller than our Sun. Proxima Centauri hosts one confirmed and one candidate planet but neither are truly in what we call a habitable zone. One planet, Proxima b, would be in a habitable zone if it weren’t for the star’s constant and violent flare outbursts. The other, Proxima c, is too far away for liquid water to form, and we’re not sure it has water at all. There is a third planet candidate, but it orbits super close to Proxima Centauri, and its surface is likely molten.

Unfortunately, the bigger siblings seem to not have any planets in orbit. They are more Sun-like and possibly more life-friendly within their habitable zones.

Our next neighbor-6 light years away, is Barnard’s Star, a red dwarf, and a star on the move. It is the fastest moving star in our sky at 310,000 mph, and a flare star like Proxima Centauri, and no known planets in orbit. Its claim to fame is inclusion in The Hitchhiker’s Guide to the Galaxy.

Wolf 359, Another red dwarf, is 7.9 light years from us and a flare star. Red dwarfs seem to have an attitude! Maybe that’s why it was picked for Star Trek: The Next Generation: Battle of Wolf 359. It has one confirmed planet, a large, Neptune-like planet orbiting the star every 8 Earth years. That’s far enough away to be out of flare reach anyway.

More interesting is large red-dwarf Lalande 21185. It’s 8 light years away and hosts two planets for sure, though one is way too close and hot. The other, a Neptune-like planet with an 8-year orbit is interesting, but there might be a third planet, with an orbit of 215 days. That would put it in Lalande’s habitable zone.

Then there’s Sirius, 8.6 light years from us. Young at around 200 million years, big (nearly 2x the size of the Sun), bright, and hot, Sirius has a companion, a white dwarf named, yep, Sirius B. No planets have been found around them.

Our last two neighbors on the block, BL and UV Ceti,  are red dwarfs lying 8.9 light years from us. They are companions, orbiting around each other. They are both flare stars and do not host planets.

Did you get the impression that red dwarf stars are common? You would be right; they are the most common stars in our universe!

What’s in the Sky?

June 12; after sunset; west: Venus has moved into position near open star cluster M44 (Beehive, Praesepe). Use binoculars.