English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

We present ultraviolet (UV) observations of six nearby Type~Ia supernovae(SNe~Ia) obtained with the Hubble Space Telescope, three of which were alsoobserved in the near-IR (NIR) with Wide-Field Camera~3. UV observations withthe Swift satellite, as well as ground-based optical and near-infrared dataprovide complementary information. The combined data-set covers the wavelengthrange $0.2$--$2~\mu$m. By also including archival data of SN 2014J, we analysea sample spanning observed colour excesses up to $E(B-V)=1.4~$mag. We study thewavelength dependent extinction of each individual SN and find a diversity ofreddening laws when characterised by the total-to-selective extinction $R_V$.In particular, we note that for the two SNe with $E(B-V)\gtrsim1~$mag, forwhich the colour excess is dominated by dust extinction, we find$R_V=1.4\pm0.1$ and $R_V=2.8\pm0.1$. Adding UV photometry reduces theuncertainty of fitted $R_V$ by $\sim50\,$% allowing us to also measure $R_V$ ofindividual low-extinction objects which point to a similar diversity, currentlynot accounted for in the analyses when SNe~Ia are used for studying theexpansion history of the universe.

Diversity in extinction laws of Type Ia supernovae measured between $0.2$ and $2\,\mu\mathrm{m}$