The methyl radical (CH3) was detected toward Sgr A*
(the galactic center) by Feuchtgruber et al. in 2000
with the Infrared Space Observatory (ISO). Unlike most observed interstellar
astromolecules, the methyl radical has no dipole moment
and thus can't be detected with pure
rotational spectroscopy. However, two of the distinctive
features of CH3 were observed. Knez et al.
reported confirming evidence of CH3 toward
NGC 7538 IRS 1 in 2009.
Contrary to VSEPR theory logic, the methyl radical is planar.
The images below depict the ν2 vibrational mode that gives rise to the observed features (left), the bonding
diagram for CH3 showing the singly occupied 2p orbital on C (center), and an isodensity surface for that