Revisiting the Chemical Composition of WD 1145+017: Impact of Circumstellar Disks Contamination on Photospheric Abundances

TL;DR

This study refines the chemical composition analysis of WD 1145+017 by accounting for circumstellar disk contamination, revealing a complex elemental makeup and emphasizing the importance of proper absorption modeling in white dwarf studies.

Contribution

It provides an improved disk model with enhanced opacity calculations and identifies a broader range of elements in both the disk and photosphere, highlighting the impact of circumstellar absorption on abundance measurements.

Findings

Detected 16 elements in the photosphere, including P, Co, and Cu.

Identified at least 10 elements in the circumstellar disk, including Na.

Found that the disk and photosphere compositions are consistent with CI Chondrite.

Abstract

We performed a chemical analysis of the asteroid-bearing white dwarf WD 1145+017 using optical and ultraviolet spectroscopic data from 25 epochs between 2015 and 2023. We present an updated gas disk model with improved opacity calculations and temperature profiles to properly account for all circumstellar absorption features. Incorporating these changes into our models, we identified at least 10 elements in the disk, including a detection of circumstellar Na. We detected 16 elements in the photosphere, including new detections of P, Co and Cu. At 16 elements, WD 1145+017 ties GD 362 as one of the most polluted white dwarfs in terms of the number of elements detected. We find that both the disk and photosphere compositions align, to first order, with CI Chondrite. Our study underscores the importance of accounting for circumstellar absorption, as neglecting them leads to significant abundance errors. Additionally, the analysis of the disk's opacity highlighted a ultraviolet flux reduction due to a pseudo-continuum due to a optically thick component. This result may affect previous analyses of other polluted white dwarfs, suggesting a need for revisiting some studies.