HUGE props to DC Comics on this one. The company is releasing a new book this week (Action Comics Superman #14) that addresses several heretofore unanswered questions about Krypton and the star it orbits. But here's the kicker: they consulted Neil deGrasse Tyson — the sexiest astrophysicist on Earth and director of NYC's Hayden Planetarium — for astronomical advice (yes, DC has elected to weave an actual star into Superman canon); AND THEN THEY PUT HIM IN THE COMIC.
Bad Astronomy's Phil Plait was given an advance copy, and he says the science and the story are both pretty great — thanks in no small part to Tyson's input:
Actually, Neil did more than just appear in the comic: he was approached by DC to find a good star to fit the story. Red supergiants don't work; they explode as supernovae when they are too young to have an advanced civilization rise on any orbiting planets. Red giants aren't a great fit either; they can be old, but none is at the right distance to match the storyline. It would have to be a red dwarf: there are lots of them, they can be very old, and some are close enough to fit the plot.
I won't keep you in suspense: the star is LHS 2520, a red dwarf in the southern constellation of Corvus (at the center of the picture here). It's an M3.5 dwarf, meaning it has about a quarter of the Sun's mass, a third its diameter, roughly half the Sun's temperature, and a luminosity of a mere 1% of our Sun's. It's only 27 light years away – very close on the scale of the galaxy – but such a dim bulb you need a telescope to see it at all (for any astronomers out there, the coordinates are RA: 12h 10m 5.77s, Dec: -15° 4m 17.9 s).
Plait's got the full science-laden, spoiler-free scoop over at Bad Astronomy.