Unveiling the 3D structure of nova shells with MUSE: The case of RR Pic

Abstract

Nova eruptions occur in cataclysmic variables when enough material has been accreted onto the surface of the white dwarf primary. As a consequence, the material that has been accumulated until then is expelled into the interstellar medium, forming an expanding nova shell around the system. Understanding the physical process that shapes the morphology of nova shells is essential to fully comprehend how the ejection mechanism operates during nova eruptions. Because of its closeness and age, the nova shell around the classical nova RR Pic (Nova Pic 1925) is an ideal target for studying the evolving morphology of nova shells. The use of integral field spectroscopy (IFS) is a technique that has received little attention in the study of nova shells, despite the advantages in using it when studying the morphology and kinematics of nova shells. In this work, we present an IFS study of the RR Pic nova shell, with a particular emphasis on the extraction of the 3D morphology of the shell. The nova shell was observed by the Multi-Unit Spectroscopic Explorer (MUSE) instrument placed at the ESO-VLT. By measuring the extension of the nova shell in these new observations, and comparing it against previous measurements, we were able to determine the expansion history of the ejected material. We used this information, together with the distance to the system based on Gaia EDR3 parallaxes, and the systemic velocity of the system reported in the literature to obtain the physical 3D view of the shell. The MUSE datacube confirms the presence of the nova shell in H$ H$ and O iii and very faintly in N ii . A comparison with previous observations suggests that the shell continues in its free-expansion phase but with the different parts of the shell apparently expanding at different rates. The data analysis corroborates the previous vision that the shell is composed of an equatorial ring and polar filaments traced by H$ At the same time, the new data also reveal that O iii is confined in gaps located in the tropical regions of the shell where no Hydrogen is observed. The flux measurements indicate that sim 99<!PCT!> of the shell flux is confined to the equatorial ring, while the polar filaments show a flux asymmetry between the NE and SW filaments, with the latter being sim 2.5 times brighter. We have estimated the mass of the shell to be sim 5times 10$^ $M$_ From the analysis of the 3D-extracted data, we determine that the ring structure extends sim 8\,000 au from the central binary, and has a position angle of sim 155 deg and an inclination of sim 74 deg. The analysis of the equatorial ring reveals it is composed of a main ring and several small clouds, extending up to a height of sim 4\,000 au above and below the main plane of the equatorial ring. The radial profile of the whole ring structure is reminiscent of a bow shock. Our data have proven the capabilities of observing nova shells using IFS, and how the nova shell around RR Pic is an interesting object of study. Further and continuous observations of the shell across the electromagnetic spectrum are required to confirm the results and ideas presented in this work.

A Photoionization Model for the Infrared Coronal Line Emission in the Classical Nova V1716 Scorpii

“…The dimension of this gas is defined by an inner radius r in (cm), thickness r d (cm), and the height of the cylinder h (cm). CNe often exhibit asymmetric geometries that are highly nonspherical, containing knots and clumps of material (for example V1280 Sco, T Pydixis, or RR Pic, Chesneau et al 2012;Toraskar et al 2013;Celedón et al 2024) motivating use of a cylindrical model. The solar abundances called in the Cloudy modeling are from Grevesse et al (2010).…”