Upon its discovery in 2006 , the young L7.5 companion to the solar analog HD 203030 was found to be unusual in being \approx 200 K cooler than older late-L dwarfs .
HD 203030B offered the first clear indication that the effective temperature at the L-to-T spectral type transition depends on surface gravity : now a well-known characteristic of low-gravity ultra-cool dwarfs .
An initial age analysis of the G8V primary star indicated that the system was 130–400 Myr old , and so the companion between 12–31 M _ { Jup } .
Using moderate resolution near-infrared spectra of HD 203030B , we now find features of very low gravity comparable to those of 10–150 Myr-old L7–L8 dwarfs .
We also obtained more accurate near infrared and Spitzer /IRAC photometry , and find a ( J - K ) _ { MKO } color of 2.56 \pm 0.13 mag—comparable to those observed in other young planetary-mass objects—and a luminosity of log ( L _ { bol } / L _ { \odot } ) = -4.75 \pm 0.04 dex .
We further reassess the evidence for the young age of the host star , HD 203030 , with a more comprehensive analysis of the photometry and updated stellar activity measurements and age calibrations .
Summarizing the age diagnostics for both components of the binary , we adopt an age of 100 Myr for HD 203030B and an age range of 30–150 Myr .
Using cloudy evolutionary models , the new companion age range and luminosity result in a mass of 11 M _ { Jup } with a range of 8–15 M _ { Jup } , and an effective temperature of 1040 \pm 50 K .