Browsing by Author "Danziger, I. John"
Now showing 1 - 2 of 2
Results Per Page
Sort Options
Item Final Spitzer IRAC Observations of the Rise and Fall of SN 1987A(The American Astronomical Society, 2020-02-06) Arendt, Richard; Dwek, Eli; Bouchet, Patrice; Danziger, I. John; Gehrz, Robert D.; Park, Sangwook; Woodward, Charles E.Spitzer's final Infrared Array Camera observations of SN 1987A show the 3.6 and 4.5 μm emission from the equatorial ring (ER) continues a period of steady decline. Deconvolution of the images reveals that the emission is dominated by the ring, not the ejecta, and is brightest on the west side. Decomposition of the marginally resolved emission also confirms this, and shows that the west side of the ER has been brightening relative to the other portions of the ER. The infrared morphological changes resemble those seen in both the soft X-ray emission and the optical emission. The integrated ER light curves at 3.6 and 4.5 μm are more similar to the optical light curves than the soft X-ray light curve, though differences would be expected if dust is responsible for this emission and its destruction is rapid. Future observations with the James Webb Space Telescope will continue to monitor the ER evolution, and will reveal the true spectrum and nature of the material responsible for the broadband emission at 3.6 and 4.5 μm. The present observations also serendipitously reveal a nearby variable source, subsequently identified as a Be star, that has gone through a multiyear outburst during the course of these observations.Item Infrared Continuum and Line Evolution of the Equatorial Ring around SN 1987A(IOP Science, 2016-02-18) Arendt, Richard; Dwek, Eli; Bouchet, Patrice; Danziger, I. John; Frank, Kari A.; Gehrz, Robert D.; Park, Sangwook; Woodward, Charles E.Spitzer observations of SN 1987A have now spanned more than a decade. Since day ∼4000, mid-infrared (mid-IR) emission has been dominated by that from shock-heated dust in the equatorial ring (ER). From 6000 to 8000 days after the explosion, Spitzer observations included broadband photometry at 3.6–24 μm, and low and moderate resolution spectroscopy at 5–35 μm. Here we present later Spitzer observations, through day 10,377, which include only the broadband measurements at 3.6 and 4.5 μm. These data show that the 3.6 and 4.5 μm brightness has clearly begun to fade after day ∼8500, and no longer tracks the X-ray emission as well as it did at earlier epochs. This can be explained by the destruction of the dust in the ER on timescales shorter than the cooling time for the shocked gas. We find that the evolution of the late time IR emission is also similar to the now fading optical emission. We provide the complete record of the IR emission lines, as seen by Spitzer prior to day 8000. The past evolution of the gas as seen by the IR emission lines seems largely consistent with the optical emission, although the IR [Fe ii] and [Si ii] lines show different, peculiar velocity structures.