AD Leonis is a young, magnetically active red dwarf in Leo, one of the most studied flare stars in the sky, prone to sudden violent outbursts.
At a glance
| type | red dwarf (class M) |
|---|---|
| distance from the Sun | 16.2 light-years (4.97 pc) |
| its light left it | 16.2 years ago |
| luminosity | 0.023 × the Sun |
| radius | 0.39 × the Sun |
| surface temperature | 3,390 K |
Read off the piece’s own catalogue, the same values it draws with.
About AD Leonis
AD Leonis is a red dwarf with a strong magnetic field and a fast rotation for a star of its kind, both signs that it is relatively young. Its surface is marked by large starspots, and it flares often, sometimes brightening noticeably within minutes.
Because it is close and active, it has been watched across the spectrum, from radio to X-rays, as a test case for how stars like it behave. Flares of this kind matter for planets around red dwarfs: their radiation and particles could strip atmospheres from worlds orbiting close to such stars.
What you see in the piece
From Earth it is below the naked-eye limit in the piece, in Leo not far from Regulus on the sky. Close up it is an orange-red disc.
Measured or modelled
A planet was proposed from a regular shift in the star’s spectrum, but later work argued that the signal is produced by starspots carried round as the star rotates. Whether a planet is there is still unsettled.
Questions
Why is AD Leonis called a flare star?
Its strong magnetic field stores energy that is released in sudden flares, which brighten the star sharply and emit strongly in X-rays and radio.