Wolf 359 - Properties

Properties

Wolf 359 has a stellar classification of M6.5, although various sources list a spectral class of M5.5, M6 or M8. An M-type star is known as a red dwarf: it is called red because the energy emission of the star reaches a peak in the red and infrared parts of the spectrum. Wolf 359 has a very low luminosity, emitting about 0.1% of the Sun's energy. If it were moved to the location of the Sun, it would appear ten times as bright as the full Moon.

At an estimated 9% of the Sun's mass, Wolf 359 is just above the lowest limit at which a star can perform hydrogen fusion through the proton–proton chain reaction: 8% of the Sun's mass. (Substellar objects below this limit are known as brown dwarfs.) The radius of Wolf 359 is an estimated 16% of the Sun's radius, or about 110,000 km. For comparison, the equatorial radius of the planet Jupiter is 71,492 km, which is 65% as large as Wolf 359's.

The entire star is undergoing convection, whereby the energy generated at the core is being transported toward the surface by the convective motion of plasma, rather than by transmission through radiation. This circulation redistributes any accumulation of helium that is generated through stellar nucleosynthesis at the core throughout the star. This process will allow the star to remain on the main sequence as a hydrogen fusing star proportionately longer than a star such as the Sun where helium steadily accumulates at the core. In combination with a lower rate of hydrogen consumption due to its low mass, the convection will allow Wolf 359 to remain a main-sequence star for about eight trillion years.

A search of this star by the Hubble Space Telescope revealed no stellar companions, although this does not preclude the presence of smaller companions that are below the telescope's detection limit, such as a planet orbiting within one astronomical unit of the star. No excess infrared emission has been detected, which may indicate the lack of a debris disk in orbit around it. Radial velocity measurements of this star using the Near Infrared Spectrometer (NIRSPEC) instrument at the Keck II observatory have not revealed any variations that might otherwise indicate the presence of an orbiting companion. This instrumentation is sensitive enough to detect the gravitational perturbations massive, short period companions with the mass of Neptune or greater.