Gliese 412

Lore & Background

The system, also known as Lalande 21258, was announced in 1860 as a high apparent proper motion star by Friedrich Wilhelm Argelander as a result of work on the Bonner Durchmusterung. Adalbert Krueger, an assistant to the BD project, was tasked with measuring its parallax and dubbed it Argelander's Third Star. The primary star was monitored for radial velocity variations caused by a Jupiter-mass companion in a short-period orbit, but no significant excess was found. A search using near-infrared speckle interferometry also failed to detect a companion at 1–10 AU, nor has a brown dwarf been detected.

Reader's Guide

Gliese 412 is significant as a nearby binary system that provides insight into the properties and dynamics of low-mass red dwarfs. The secondary component, WX Ursae Majoris, is a flare star of the UV Ceti type, observed to flare as early as 1939 by Adriaan van Maanen. It has been identified as an X-ray source, while the primary shows no significant X-ray emission. The system's space velocity components (U = 141, V = –7, W = 7) indicate it is a member of the halo population of the Milky Way. Despite searches, no planetary or brown dwarf companions have been detected, underscoring the challenges in finding substellar objects around such faint stars. The projected separation of the components is about 152 AU, with an estimated orbital semimajor axis of 190 AU.

Did You Know?

• The secondary component, Gliese 412 B, is a flare star known as WX Ursae Majoris.
• The system was announced in 1860 as a high proper motion star by Friedrich Wilhelm Argelander.
• No significant X-ray emission was detected from the primary component, while the secondary is an X-ray source.
• From the B component, the A component would appear about as bright as a First Quarter Moon.