. Back to the Page of Chemical Elements . Electron configuration: 1s 2 2s 2 2p 4 . Solar Abundance: 8.87 ? 0.07 (Grevesse et al. 1996) . ION . Spectrum . Configuration . I.P. (eV) . O . OI . 1s 2 2s 2 2p 4 . O + . OII . 1s 2 2s 2 2p 3 . O 2+ . OIII . 1s 2 2s 2 2p 2 . O 3+ . OIV . 1s 2 2s 2 2p . O 4+ . OV . 1s 2 2s 2 . O 5+ . OVI . 1s 2 2s . O 6+ . OVII . 1s 2 . O 7+ . OVIII . 1s . References: . Grevesse N., Noels A., Sanyal A.J. 1996, ASP Conf. Series, 99 ,117-126

... We explore the structures immediately surrounding the intermediate-mass young stellar object R Mon with bispec- trum speckle interferometry, conventional near-infrared imaging and by analyzing optical HST archive data. Our near-infrared speckle images with unprecedented diffraction-limited resolution of 55 mas (44 AU; H -band) and 76 mas (61 AU; K -band) represent the highest resolution R Mon images obtained so far and exhibit previously unseen complex structures. ... The features 1­5 are marked. ...