A study of two young multipolar planetary nebulae: Hen 2-73 and Hen 2-96

¹ College of Geo-exploration Science and Technology, Jilin University, Changchun 130012, PR China
² Institute of Integrated Information for Mineral Resources Prediction, Jilin University, Changchun 130012, PR China
e-mail: wangyongzhi@jlu.edu.cn
³ Laboratory for Space Research, Faculty of Science, The University of Hong Kong, Hong Kong, China
e-mail: xiazh.tw@yahoo.com.tw
⁴ Shekou International School Secondary Campus and ISS Asia Pacific Headquarters, Shenzhen, Guangdong Province, PR China
⁵ Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, PR China
⁶ Deep Space Exploration Laboratory, Beijing 100043, PR China
⁷ Lunar Exploration and Space Engineering Centre, China National Space Administration, Beijing 100190, PR China

Received: 27 February 2024
Accepted: 30 April 2024

Abstract

We perform an infrared (IR) spectral and visible morphological study of two young planetary nebulae (YPNe) Hen 2-73 and Hen 2-96 using archival Spitzer Space Telescope and Hubble Space Telescope (HST) observations to understand their dust properties and nebular structures. High-resolution HST images of these nebulae show several bipolar lobes and ionised tori in the central regions of both objects. The presence of these multi-lobe structures suggests that the formation process of these nebulae is complex. To search for a possible link between the central sources and multipolar appearances of these objects, the Transiting Exoplanet Survey Satellite (TESS) observations are used to examine whether their central stars (CSs) exhibit periodic photometric variations. In the TESS observations, the CS light curve of Hen 2-96 shows a photometric variation with a period of 2.23 h. The IR spectra of these two YPNe suggest that the nebulae have mixed dust environments, which are associated with the presence of dense tori created by central binary interactions in these objects. Two three-dimensional models are constructed to study the complex nebular structures of the YPNe. These simulations suggest that the number of multipolar YPNe may be larger than observed. In addition, we analyse the spectral energy distributions of these nebulae to study their gas, dust, and photospheric components.