Chemical abundances in the protoplanetary disk LV2 (Orion): clues to the causes of the abundance anomaly in HII regions

Abstract

Optical integral field spectroscopy of the archetype protoplanetary disk LV2 in the Orion Nebula is presented, taken with the VLT FLAMES/Argus fibre array. The detection of recombination lines of CII and OII from this class of objects is reported, and the lines are utilized as abundance diagnostics. The study is complemented with the analysis of HST Faint Object Spectrograph ultraviolet and optical spectra of the target contained within the Argus field of view. By subtracting the local nebula background the intrinsic spectrum of the proplyd is obtained and its elemental composition is derived for the first time. The proplyd is found to be overabundant in carbon, oxygen and neon compared to the Orion Nebula and the sun. The simultaneous coverage over LV2 of the CIII] 1908-A and [OIII] 5007-A collisionally excited lines (CELs) and CII and OII recombination lines (RLs) has enabled us to measure the abundances of C++ and O++ for LV2 with both sets of lines. The two methods yield consistent results for the intrinsic proplyd spectrum, but not for the proplyd spectrum contaminated by the generic nebula spectrum, thus providing one example where the long-standing abundance anomaly plaguing metallicity studies of HII regions has been resolved. These results would indicate that the standard forbidden-line methods used in the derivation of light metal abundances in HII regions in our own and other galaxies underestimate the true gas metallicity.

Accepted by MNRAS November 8; 16 pages, 9 figs; typos corrected, error in FWHMs in table 4 corrected in this version

References in corpus (13)

• Trigonometric Parallaxes of Massive Star Forming Regions: VI. Galactic Structure, Fundamental Parameters and Non-Circular Motions
• Keck HIRES Spectroscopy of Extragalactic HII Regions: C and O Abundances from Recombination Lines
• Chemical abundances of 451 stars from the HARPS GTO planet search program: Thin disc, thick disc, and planets
• Properties of the ionized gas in HH202. II: Results from echelle spectrophotometry with UVES
• Integral field spectroscopy of planetary nebulae: mapping the line diagnostics and hydrogen-poor zones with VLT FLAMES
• Spitzer reveals what's behind Orion's Bar
• Deviations from He I Case B Recombination Theory and Extinction Corrections in the Orion Nebula
• Spectrophotometry of the Huygens Region of the Orion Nebula, the Extended Orion Nebula, and M~43; Scattered Light Systematically Distorts Conditions Derived from Emission-Lines
• Argon Abundances in the Solar Neighborhood: Non-LTE Analysis of Orion Association B-type Stars
• Small scale behavior of the physical conditions and the abundance discrepancy in the Orion nebula
• A photoionized Herbig-Haro object in the Orion nebula
• Small-spatial scale variations of nebular properties and the abundance discrepancy in three Galactic HII regions
• Integral field spectroscopy of protoplanetary disks in Orion with VLT FLAMES

Cited by in corpus (17)

• Nebular spectroscopy: A guide on H II regions and planetary nebulae
• Binarity and the abundance discrepancy problem in planetary nebulae
• NGC 2579 and the carbon and oxygen abundance gradients beyond the solar circle
• Imaging the elusive H-poor gas in the high ADF planetary nebula NGC 6778
• MUSE spectroscopy of planetary nebulae with high abundance discrepancies
• Analysis of two SMC HII Regions Considering Thermal Inhomogeneities: Implications for the Determinations of Extragalactic Chemical Abundances
• Photoionized Herbig-Haro objects in the Orion Nebula through deep high-spectral resolution spectroscopy I: HH529II and III
• Densities, temperatures, pressures, and abundances derived from OII recombination lines in HII regions and their implications
• The Discrepant Kinematics of ORLs and CELs in NGC 7009 as a Function of Ionization Structure
• The Oxygen Abundance in the Solar Neighborhood
• The Kinematics of the Permitted C II $\lambda$ 6578 Line in a Large Sample of Planetary Nebulae
• Chemical abundances in Orion protoplanetary discs: integral field spectroscopy and photoevaporation models of HST 10
• Chemical abundances in the protoplanetary disk LV2 (Orion) - II: High dispersion VLT observations and microjet properties
• Neon Insights from Old Solar X-rays: a Plasma Temperature Dependence of the Coronal Neon Content
• Deep high spectral resolution spectroscopy and chemical composition of ionized nebulae
• Physical conditions and chemical abundances in photoionized nebulae from optical spectra
• Searching for intergalactic star forming regions in Stephan's Quintet with SITELLE: II. Physical properties and metallicity