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

SN2011ht has been described both as a true supernova and as an impostor. Inthis paper, we conclude that it does not match some basic expectations for acore-collapse event. We discuss SN2011ht's spectral evolution from a hot densewind to a cool dense wind, followed by the post-plateau appearance of a fasterlow density wind during a rapid decline in luminosity. We identify a slow densewind expanding at only 500--600 km/s, present throughout the eruption. A fasterwind speed V ~ 900 km/s may be identified with a second phase of the outburst.There is no direct or significant evidence for any flow speed above 1000 km/s;the broad asymmetric wings of Balmer emission lines in the hot wind phase weredue to Thomson scattering, not bulk motion. We estimate a mass loss rate oforder 0.04 Msun/yr during the hot dense wind phase of the event. There is noevidence that the kinetic energy substantially exceeded the luminous energy,roughly 2 X 10^49 ergs; so the total energy was far less than a true SN. Wesuggest that SN2011ht was a giant eruption driven by super-Eddington radiationpressure, perhaps beginning about 6 months before the discovery. A stronglynon-spherical SN might also account for the data, at the cost of more freeparameters.

The Unusual Temporal and Spectral Evolution of SN2011ht. II. Peculiar Type IIn or Impostor?