Optical Spectroscopy and Photoionization Model of NGC 6572 Muhammad Fajrin (a), Hakim L. Malasan(a,b,c,d,*), Evan I. Akbar(a,b), Aliyya N. Rahma(a), Irfan Imaduddin(a), Agus T. P. Jatmiko (b)
a) Department of Astronomy, Bandung Institute of Technology
Jalan Ganesha 10, Bandung 40132, Indonesia
b) Bosscha Observatory, Institut Teknologi Bandung
Jalan Peneropongan Bintang, Bandung Barat 40391, Indonesia
c) Atmospheric and Planetary Science Study Program, Institut Teknologi Sumatera, Lampung, Indonesia
Jalan Terusan Ryacudu, Lampung Selatan 35365, Indonesia
d) ITERA Astronomical Observatory, Sumatera Institute of Technology
Jalan Terusan Ryacudu, Lampung Selatan 35365, Indonesia
*Email: hakim[at]as.itb.ac.id
Abstract
We investigate the planetary nebula NGC 6572 through optical spectroscopy carried out at the Bosscha Observatory to determine its kinematical and chemical properties. Two intermediate dispersion spectra (R\(sim\)5000) centered around H\(alpha\) and H\(beta\) each obtained using Shelyak^s LHIRES III (1200 grooves/mm) spectrograph mounted on 10inch SCT Meade LX200R (F/9.84) are used to derive the nebular expansion velocity from emission lines associated with H\(alpha\), H\(beta\), [OIII], [NII], and [SII] ions. One low dispersion spectrum (R\(sim\)1000) obtained using 11inch SCT Celestron C11 (F/10) and NEO-R1000 (600 grooves/mm) long-slit spectrograph is used to determine nebular electron temperature, electron density, and its chemical composition. We also perform photoionization modelling to construct a self-consistent nebular model using Cloudy C17.02 to obtain reliable physical quantities.
Spectral images of the intermediate resolution spectra successfully show the global elliptical structure of the nebula. The expansion velocity deduced from most of the emission lines agree with the published values which is around 15-20 Km/s. The deduced nebular physical properties also agree well with those determined by other works. Nebular abundances are substantially lower than that of solar, except for oxygen. Discrepancies are apparent when comparing line intensities of the observed data with the ones resulted from photoionization model. Further spectroscopic observations with higher resolution and with various position angle will be very useful to reveal more complete and detail structure of the nebula while spectra that covers wider wavelength range are recommended to better deduce the nebular physical properties.
Keywords: Spectroscopy- Planetary nebula- Expansion velocity- Chemical abundance- Photoionization model
