Brown Dwarfs Archives

This infographic compares the characteristics of three classes of stars in our galaxy: Sunlike stars are classified as G stars; stars less massive and cooler than our Sun are K dwarfs; and even fainter and cooler stars are the reddish M dwarfs. The graphic compares the stars in terms of several important variables. The habitable zones, potentially capable of hosting life-bearing planets, are wider for hotter stars. The longevity for red dwarf M stars can exceed 100 billion years. K dwarf ages can range from 15 to 45 billion years. And, our Sun only lasts for 10 billion years. The relative amount of harmful radiation (to life as we know it) that stars emit can be 80 to 500 times more intense for M dwarfs relative to our Sun, but only 5 to 25 times more intense for the orange K dwarfs. Red dwarfs make up the bulk of the Milky Way's population, about 73%. Sunlike stars are merely 6% of the population, and K dwarfs are at 13%. When these four variables are balanced, the most suitable stars for potentially hosting advanced life forms are K dwarfs. Credits: NASA, ESA and Z. Levy (STScI) Larger image

Alpha Centauri, Biosignatures & Paleobiology, Brown Dwarfs, Epsilon Eridani, Exoplanets, -moons, -comets, Habitable Zones, Press Release, Proxima Centauri, tau Ceti, TRAPPIST-1

Goldilocks Stars Are Best Places to Look for Life

by Keith CowingJanuary 8, 2020August 13, 2025

In the search for life beyond Earth, astronomers look for planets in a star’s “habitable zone” — sometimes nicknamed the “Goldilocks zone” — where temperatures are just right for liquid […]

Brown Dwarfs

Brown Dwarf Atmospheres As The Potentially Most Detectable And Abundant Sites For Life

by Keith CowingMay 28, 2019

We show that the total habitable volume in the atmospheres of cool brown dwarfs with effective temperatures of ∼250-350 K is possibly larger by two orders of magnitude than that […]

Astronomy & Telescopes, Brown Dwarfs, Exoplanets, -moons, -comets, Status Report

A Search For Rocky Planets Transiting Brown Dwarfs

by Keith CowingApril 28, 2013November 30, 2023

Exoplanetary science has reached a historic moment. The James Webb Space Telescope will be capable of probing the atmospheres of rocky planets, and perhaps even search for biologically produced gases. […]