Towards an improvement in the spectral description of central stars of planetary nebulae

WEIDMANN, W.; GAMEN, R.; MAST, D.; FARIÑA, C.; GIMENO, G.; SCHMIDT, E. O.; ASHLEY, R. P.; DE ARRIBA, L. PERALTA; SOWICKA, P.; ORDONEZ-ETXEBERRIA, I.

ASTRONOMY AND ASTROPHYSICS

EDP SCIENCES S A

Lugar: Paris; Año: 2018 vol. 614 p. 135 - 171

0004-6361

Context. There are more than 3000 known Galactic planetary nebulae, butonly 492 central stars of Galactic planetary nebulae (CSPN) have knownspectral types. It is vital to increase this number in order to havereliable statistics, which will lead to an increase of our understandingof these amazing objects. Aims: We aim to contribute to theknowledge of central stars of planetary nebulae and stellar evolution. Methods: This observational study is based on Gemini Multi-ObjectSpectrographs (GMOS) and with the Intermediate Dispersion Spectrograph(IDS) at the Isaac Newton Telescope spectra of 78 CSPN. The objects wereselected because they did not have any previous classification, or thepresent classification is ambiguous. These new high quality spectraallowed us to identify the key stellar lines for determining spectralclassification in the Morgan-Keenan (MK) system. Results: We haveacquired optical spectra of a large sample of CSPN. From the observedtargets, 50 are classified here for the first time while for 28 theexisting classifications have been improved. In seven objects we haveidentified a P-Cygni profile at the He I lines. Six of these CSPN arelate O-type. The vast majority of the stars in the sample exhibit anabsorption-type spectrum, and in one case we have found wide emissionlines typical of [WR] stars. We give a complementary, and preliminary,classification criterion to obtain the sub-type of the O(H)-type CSPN.Finally, we give a more realistic value of the proportion of CSPN thatare rich or poor in hydrogen.