DOI: 10.5061/dryad.j6q573nm7
title: Supplemental data and figures behind: Atomic-scale element and isotopic investigation of 25Mg-rich stardust from a H-burning supernova

description: We have discovered a presolar olivine from ALH 77307 with the
 highest 25Mg isotopic composition measured in a silicate to date
 (δ25Mg = 3025.1‰ ± 38.3‰). Its isotopic compositions challenge current
 stellar models, with modelling of Mg, Si and O showing a closest match to
 formation in a supernova where hydrogen ingestion occurred in the
 pre-supernova phase. Presolar grains within primitive astromaterials
 retain records of processes and environmental changes throughout stellar
 evolution. However, accessing these records has proved challenging due to
 the average grain size (~150 nm) of presolar silicates, their sensitivity
 to extraction agents and instrumental restrictions, limiting the range of
 isotopic and chemical signatures which can be studied per grain volume.
 Here, we present the first known detailed, geochemical study of a presolar
 silicate from a H-burning supernova, studied in 3D without contributions
 to the analysis volume and at unprecedented spatial resolutions (&lt;
 1 nm), essential for constraining physical and chemical processes
 occurring within this recently proposed stellar environment. From our
 results, we infer either; [1] condensation within an environment depleted
 of heavy elements compatible with the olivine lattice under the pressure
 and temperature conditions during condensation. [2] during periods of
 limited mixing either near the end of the pre-supernova phase or from a
 collapse so rapid localised pockets of different gas compositions formed.
description: NanoSIMS (Secondary ion mass spectrometry) ion imaging was
 conducted with the CAMECA (Compagnie des Applications Mécaniques et
 Electroniques au Cinéma et à l'Atomistique) NanoSIMS 50L ion probe at
 the Centre for Microscopy, Characterisation, and Analysis (CMCA),
 University of Western Australia. Data was processed using custom in-house
 software at JSC. See the methods section of the associated manuscript for
 details. Atom probe tomography data was collected using
 the CAMECA Local Electrode Atom Probe, LEAP 4000X HR, within the
 Geoscience Atom Probe facility, at the JdLC, Curtin University. Data was
 processed using the Atom Probe (AP) Suite 6.0 processing software and
 Integrated Visualization and Analysis Software (IVAS) 3.8. Experimental
 conditions, acquisition parameters, data reconstruction parameters and
 data processing methods are detailed within the methods of the associated
 manuscript. 
description: Any free imaging software can be used to open these files. 
description: # Supplemental data and figures behind: Atomic-scale element and isotopic
 investigation of 25Mg-rich stardust from a H-burning supernova ---
 Uploaded is ion imaging, scanning electron microscopy (SEM) imaging and
 atom probe tomography (APT) reconstruction and spectra. ## Description of
 the data and file structure This is the processed data from which the
 figures and relationships were determined. The spectra from APT can be
 used for studying chemistry in the measured presolar grain (uploaded as a
 jpeg), ion images can be used for determining its isotopic signature
 (exported from NanoSIMS data processing software and uploaded as a jpeg),
 and SEM images give local context and a visual look at the identified
 grain in this study. The SEM images are BSE images of the presolar grain
 in the mineral matrix in ALH 77307. The Excel document details the
 isotopic calculations. The first tab has Mg and Si isotopic values
 determined using Atom Probe Tomography and which peaks were used for the
 calculation. Most atoms are concentrated at the Mg++ peak (~90% of total
 Mg atoms in the presolar grain), followed by Mg+ and MgO+ (O is removed
 for the calculation). The second tab details the Si and O isotopic
 calculations made during NanoSIMS, chemical abundances determined using
 APT, physical properties from SEM, and modeling outcomes. For more
 details, see the main manuscript.