English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

The mechanism behind the shaping of bipolar planetary nebulae is still poorlyunderstood. Accurately tracing the molecule-rich equatorial regions of post-AGBstars can give valuable insight into the ejection mechanisms at work. Weinvestigate the physical conditions, structure and velocity field of the densemolecular region of the planetary nebula NGC 6302 by means of ALMA band 7interferometric maps. The high spatial resolution of the $^{12}$CO and$^{13}$CO J=3-2 ALMA data allows for an analysis of the geometry of the ejectain unprecedented detail. We built a spatio-kinematical model of the molecularregion with the software SHAPE and performed detailed non-LTE calculations ofexcitation and radiative transfer with the SHAPEMOL plug-in. We find that themolecular region consists of a massive ring out of which a system of fragmentsof lobe walls emerge and enclose the base of the lobes visible in the optical.The general properties of this region are in agreement with previous works,although the much greater spatial resolution of the data allows for a verydetailed description. We confirm that the mass of the molecular region is 0.1M$_{\odot}$. Additionally, we report a previously undetected component at thenebular equator, an inner, younger ring inclined $\sim$60$^\circ$ with respectto the main ring, showing a characteristic radius of 7.5$\times$10$^{16}$ cm, amass of 2.7$\times$10$^{-3}$ M$_{\odot}$, and a counterpart in optical imagesof the nebula. This inner ring has the same kinematical age as the northwestoptical lobes, implying it was ejected approximately at the same time, hundredsof years after the ejection of the bulk of the molecular ring-like region. Wediscuss a sequence of events leading to the formation of the molecular andoptical nebulae, and briefly speculate on the origin of this intriguing innerring.

ALMA high spatial resolution observations of the dense molecular region of NGC 6302