Climate Change Impacts on the Energy Sector and Adaptation Options

The Near-Ultraviolet Luminosity Function of Young, Early M-Type Dwarf Stars

“…Instead, this locus likely indicates persistent NUV line emission from a higher-temperature upper chromosphere. Stelzer et al (2013) previously noted that all M dwarfs appear to exhibit NUV emission in excess of their expected photospheric value from stellar atmosphere models.…”

“…Relations between stellar age and emission at highenergy wavelengths are typically expressed as twoparameter power laws of the form F λ = αt β (c.f., Ribas et al 2005) where t is the age of the star and the two parameters, α and β, are the zero point and slope of the power law, respectively. Stelzer et al (2013) derived an age-activity relation for early-M dwarfs by combing their sample of 159 nearby field M dwarfs (assuming an age of ∼3 Gyr) with an additional sample of young (∼1 Myr) M dwarfs from the TW Hya association. They found that β = −0.84 ± 0.08 at GALEX NUV wavelengths.…”

“…The Galaxy Evolution Explorer (GALEX; Martin et al 2005) is a recently decommissioned space-based telescope that performed all-sky imaging in both near-UV (NUV; 1771-2831Å) and far-UV (FUV; 1344-1768Å) bandpasses ( Figure 1). Several recent studies have used GALEX data to identify active and/or young M dwarfs (Browne et al 2009;Rodriguez et al 2011;Shkolnik et al 2011;Rodriguez et al 2013;Stelzer et al 2013). Most notably, Stelzer et al (2013) studied a volume-limited sample of 159 field M dwarfs within 10 pc, which they identified by cross-correlating the Lépine & Gaidos 2011 (hereafter LG11) catalog of bright M dwarfs with the GALEX sixth data release (GR6).…”

“…Several recent studies have used GALEX data to identify active and/or young M dwarfs (Browne et al 2009;Rodriguez et al 2011;Shkolnik et al 2011;Rodriguez et al 2013;Stelzer et al 2013). Most notably, Stelzer et al (2013) studied a volume-limited sample of 159 field M dwarfs within 10 pc, which they identified by cross-correlating the Lépine & Gaidos 2011 (hereafter LG11) catalog of bright M dwarfs with the GALEX sixth data release (GR6). They compared their sample to members of the TW Hydra young moving group (YMG), which has a known age of ∼10 Myr, to derive a power-law age-activity relation.…”

“…However, the Stelzer et al (2013) sample was too small to quantitatively describe a UV luminosity function, particularly at higher UV luminosities where there are fewer stars. Furthermore, M dwarfs can appear UV luminous for reasons other than stellar youth.…”