Ground- and Space-based Dust Observations of VV 191 Overlapping Galaxy Pair

• Published in: The Astronomical journal Vol. 167; no. 6; pp. 263 - 278
• Main Authors: Robertson, Clayton, Holwerda, Benne W., Young, Jason, Keel, William C., Berkheimer, Jessica M., Cook, Kyle, Conselice, Christopher J., Frye, Brenda L., Grogin, Norman A., Koekemoer, Anton M., Nasr, Camella-Rosa, Patel, Divya, Roemer, Wade, Smith, Dominic, Windhorst, Rogier A.
• Format: Journal Article
• Language: English
• Published: Madison The American Astronomical Society 01.06.2024; IOP Publishing
• Subjects: Astronomical models; Atmospheric particulates; Attenuation; Balmer lines; Cosmic dust; Disk galaxies; Dust; Dust content; Dust effects; Dust filters; Emission line galaxies; Galactic structure; Galaxies; Galaxy spectroscopy; Hubble Space Telescope; Interstellar dust; Interstellar dust extinction; Interstellar medium; James Webb Space Telescope; Metallicity; Star & galaxy formation; Star formation; Star formation rate; Stars; Stars & galaxies; Visible spectrum
• ISSN: 0004-6256; 1538-3881
• DOI: 10.3847/1538-3881/ad39c4

Abstract The Balmer decrement (H α /H β ) provides a constraint on attenuation, the cumulative effects of dust grains in the ISM. The ratio is a reliable spectroscopic tool for deriving the dust properties of galaxies that determine many different quantities such as star formation rate, metallicity, and SED models. Here, we measure independently both the attenuation and H α /H β of an occulting galaxy pair: VV 191. Attenuation measurements in the visible spectrum ( A V ,stars ) from dust maps derived from the F606W filter of HST and the F090W filter of JWST are matched with spaxel-by-spaxel H α /H β observations from the George and Cynthia Mitchell Spectrograph of the McDonald Observatory. The 0.5–0.7 μ m bandpass covers the Balmer lines for VV 191. The dust maps of JWST and HST provide the high sensitivity necessary for comparisons and tracking trends of the geometrically favorable galaxy. We present maps and plots of the Balmer lines for the VV 191 galaxy pair and for a specific region highlighting dust lanes for VV 191b in the overlap region. We compute A V ,H II from H α /H β and plot both quantities against A V ,stars . Our results show that regions with higher dust content, residing closer to the spiral center, dominate ionized gas attenuation, leading to an overestimation of A V ,H II by a factor of 2. Further out in the spiral arms, the lower dust content leads to more agreement between the attenuations, indicating a lower star formation rate and larger contribution from older stars to the stellar continuum outside the Petrosian radius.