Discovery of CWISE J052306.42-015355.4, an Extreme T Subdwarf Candidate

TL;DR

This paper reports the discovery of a new extreme T subdwarf candidate, identified through machine learning on infrared survey data, with estimated properties suggesting it is a nearby, high-velocity, metal-poor object.

Contribution

It introduces a new extreme T subdwarf candidate discovered via machine learning techniques applied to WISE data, expanding knowledge of such rare objects.

Findings

Proper motion of 0.52 arcsec/yr suggests high velocity.

Estimated distance of ≤68 pc indicates proximity.

Metallicity estimated between -1.5 and -0.5.

Abstract

We present the discovery of CWISE J052306.42$-$015355.4, which was found as a faint, significant proper motion object (0.52 $\pm$ 0.08 arcsec yr$^{-1}$) using machine learning tools on the unWISE re-processing on time series images from the Wide-field Infrared Survey Explorer. Using the CatWISE2020 W1 and W2 magnitudes along with a $J-$band detection from the VISTA Hemisphere Survey, the location of CWISE J052306.42$-$015355.4 on the W1$-$W2 vs. $J-$W2 diagram best matches that of other known, or suspected, extreme T subdwarfs. As there is currently very little knowledge concerning extreme T subdwarfs we estimate a rough distance of $\le$ 68 pc, which results in a tangential velocity of $\le$ 167 km s$^{-1}$, both of which are tentative. A measured parallax is greatly needed to test these values. We also estimate a metallicity of $-1.5 <$ [M/H] $< -0.5$ using theoretical predictions.