LP 413-53AB

Last night Northwestern University talked LP 413-53AB. "Ultracool" red dwarfs, in a binary hence the "AB".

A very close binary: 0.01 AU apart, 20.5 hour period. Like HD 114762.

The stars' age is estimated to be in the high billions - galactic halo, mayhap? Anyway as I've been hearing for Proxima Centauri, the older the reddwarf, the smaller and dimmer; the cold dying star trope doesn't work for G stars' systems but absolutely works for M. Nobody's told me where K stars fall in this, if they get hotter like G before ballooning out. For all I know it's a function of time like how T Tauris cool before bouncing back again.

NWU told us in which direction this binary lives - Taurus - but not the distance. It's nearby; but we could have guessed this, as it was dug out of data painstakingly interpreted, as emitting radiation mostly infrared. On the other hand if it be close as Barnard's-Star or Luhman 16, I'd expect much more hype about the short distance. So it's further than six light years from us. At least it's zodiacal so if we wanted the 550 AU Solar lens, we could use it.

We don't get masses - but they did let us ask senpai Kepler. Normalise μ such that Sol=4π²; assume LP 413-53 semimajor 0.005 AU for A or B. μ of LP 413-53AB 0.005³ (1/8000000) and 0.0023385². 0.022857 x 4π² = 28.723% M_☉ - together. Van Biesbroeck's star 19 light years away was 7.79%. EBLM J0555-57Ab likewise; wiki tells me 2MASS J0523-1403 (40 LY) is 5%-7%. But do note that the LP 413-53 system is split between two 14%/15% M_☉s and that it is super old.

GAIA DR3 2/1: Maybe someone could look up the name in Hipparchos then the general-area...

KECK 2/23: Per Zimmerman Keck have belatedly commented - this time linking the arxiv. Apparently it was 15% M_☉ together. Not sure where my mistake so I'll just need to learn to read moar. PUBLISHED 3/2: The final release to the paper. Oh look - it's free! - still with no parallax. Screw-this; let's go Simbad: Gaia EDR3 36.87 parsex. Hardly neighbors of our sun, Dr Hsu.