3 ms·

Do large, bright stars ever pass that close? What would that look like?

lisper 9y ago
> Do large, bright stars ever pass that close? Yes, but it's extremely rare. > What would that look like? Not much. The Scholz flyby was at 0.6-0.8 light years, the same order of magnitude as the distance to Alpha Centauri. It would just look like a star, probably not even a particularly bright one.
- jessriedel 9y ago
  The rate at which it was drifting with respect to the other stars might have been noticeable under long-term observations. 20 ly in 70k years means its doing about 85 km/s. At its point of closest approach, 0.6 ly, this translates to 1 radian per 2100 years, or 1 degree per 37 years. (The full moon is 1/2 a degree.) The Scholz star was too dim to see, but a brighter star following its trajectory would have noticeably moved in a constellation over the course of a human lifetime.
- mtgx 9y ago
  Alpha Centauri is 4.37 light years away. Or did I misunderstand your comment?
  - lisper 9y ago
    Hard to say. Yes, Alpha Centauri is indeed 4.37 LY away, though that kind of precision is irrelevant when talking about orders of magnitude (OOM). Two numbers are considered to be the same OOM if the absolute difference of their base-10 logarithms is less than 1.
fencepost 9y ago
The truly large bright stars don't really "live" long enough in that state to travel great distances on an astronomical scale, and if there was one in our area we'd be in trouble[1]. Large stars smaller than that but large enough to be significantly bright would probably look a lot like a planet, but long-term could also be bad for us if they were close enough and massive enough to even slightly destabilize orbits - the impact might take thousands of years to truly materialize, but climate change has nothin' on orbit change. Also, anything both large/bright enough to be easily visible AND headed in our direction would likely have been noticed at this point. It may happen someday, but the descendants of the cockroaches are the ones who'll have to deal with it. [1] http://earthsky.org/astronomy-essentials/supernove-distance http://earthsky.org/astronomy-essentials/supernove-distance

> Do large, bright stars ever pass that close? Yes, but it's extremely rare. > What would that look like? Not much. The Scholz flyby was at 0.6-0.8 light years, the same order of magnitude as the distance to Alpha Centauri. It would just look like a star, probably not even a particularly bright one.

jessriedel 9y ago
The rate at which it was drifting with respect to the other stars might have been noticeable under long-term observations. 20 ly in 70k years means its doing about 85 km/s. At its point of closest approach, 0.6 ly, this translates to 1 radian per 2100 years, or 1 degree per 37 years. (The full moon is 1/2 a degree.) The Scholz star was too dim to see, but a brighter star following its trajectory would have noticeably moved in a constellation over the course of a human lifetime.
mtgx 9y ago
Alpha Centauri is 4.37 light years away. Or did I misunderstand your comment?
- lisper 9y ago
  Hard to say. Yes, Alpha Centauri is indeed 4.37 LY away, though that kind of precision is irrelevant when talking about orders of magnitude (OOM). Two numbers are considered to be the same OOM if the absolute difference of their base-10 logarithms is less than 1.

fencepost 9y ago

The truly large bright stars don't really "live" long enough in that state to travel great distances on an astronomical scale, and if there was one in our area we'd be in trouble[1]. Large stars smaller than that but large enough to be significantly bright would probably look a lot like a planet, but long-term could also be bad for us if they were close enough and massive enough to even slightly destabilize orbits - the impact might take thousands of years to truly materialize, but climate change has nothin' on orbit change. Also, anything both large/bright enough to be easily visible AND headed in our direction would likely have been noticed at this point. It may happen someday, but the descendants of the cockroaches are the ones who'll have to deal with it. [1] http://earthsky.org/astronomy-essentials/supernove-distance http://earthsky.org/astronomy-essentials/supernove-distance