We have acquired Hubble Space Telescope ( HST ) and Very Large Telescope near-infrared spectra and images of supernova ( SN ) Refsdal after its discovery as an Einstein cross in Fall 2014 .
The HST light curve of SN Refsdal matches the distinctive , slowly rising light curves of SN 1987A-like supernovae ( SNe ) , and we find strong evidence for a broad H \alpha P-Cygni profile in the HST grism spectrum at the redshift ( z = 1.49 ) of the spiral host galaxy .
SNe IIn , powered by circumstellar interaction , could provide a good match to the light curve of SN Refsdal , but the spectrum of a SN IIn would not show broad and strong H \alpha absorption .
From the grism spectrum , we measure an H \alpha expansion velocity consistent with those of SN 1987A-like SNe at a similar phase .
The luminosity , evolution , and Gaussian profile of the H \alpha emission of the WFC3 and X-shooter spectra , separated by \sim 2.5 months in the rest frame , provide additional evidence that supports the SN 1987A-like classification .
In comparison with other examples of SN 1987A-like SNe , SN Refsdal has a blue B - V color and a high luminosity for the assumed range of potential magnifications .
If SN Refsdal can be modeled as a scaled version of SN 1987A , we estimate it would have an ejecta mass of 20 \pm 5 M _ { \odot } .
The evolution of the light curve at late times will provide additional evidence about the potential existence of any substantial circumstellar material ( CSM ) .
Using MOSFIRE and X-shooter spectra , we estimate a subsolar host-galaxy metallicity ( 8.3 \pm 0.1 dex and < 8.4 dex , respectively ) near the explosion site .