Late-Time Observations of ASASSN-14lp Strengthen the Case for a
  Correlation between the Peak Luminosity of Type Ia Supernovae and the Shape
  of their Late-Time Light Curves
  Late-time observations of Type Ia supernovae (SNe Ia), >900 days after
explosion, have shown that this type of SN does not suffer an "IR catastrophe"
at 500 days as previously predicted. Instead, several groups have observed a
slow-down in the optical light curves of these SNe. A few reasons have been
suggested for this slow-down, from a changing fraction of positrons reprocessed
by the expanding ejecta, through a boost of energy from slow radioactive decay
chains such as 57Co --> 57Fe, to atomic "freeze-out." Discovering which of
these (or some other) heating mechanisms is behind the slow-down will directly
impact studies of SN Ia progenitors, explosion models, and nebular-stage
physics. Recently, Graur et al. (2018) suggested a possible correlation between
the shape of the late-time light curves of four SNe Ia and their stretch
values, which are proxies for their intrinsic luminosities. Here, we present
Hubble Space Telescope observations of the SN Ia ASASSN-14lp at ~850-960 days
past maximum light. With a stretch of s = 1.15 +/- 0.05, it is the most
luminous normal SN Ia observed so far at these late times. We rule out
contamination by light echoes and show that the late-time, optical light curve
of ASASSN-14lp is flatter than that of previous SNe Ia observed at late times.
This result is in line with-and strengthens-the Graur et al. (2018)
correlation, but additional SNe are needed to verify it.
