Research Projects
01
AT 2016blu
We present the first photometric analysis of AT 2016blu, a supernova impostor in NGC 4559. Our study reveals 19 outbursts between 2012 and 2022, with irregular light curves and recurring peaks every 113 ± 2 days. We propose that AT 2016blu's outbursts are driven by periastron interactions in an eccentric binary system, possibly involving a luminous blue variable (LBV). The resemblance to eta Carinae and SN 2009ip suggests a potential catastrophic event in the future, making AT 2016blu an interesting target for further investigation.
02
SN 2000ch
SN 2000ch experienced four outbursts in 2000-2010. Using new photometric observations, we find that SN 2000ch experienced at least nine more outbursts in 2017-2022 with a wide variety of peak magnitude, duration,
and shape. We find that the eruptive outbursts repeat with a period of around 200 days. A regular periodicity suggests that SN 2000ch's eruptions are caused by interaction around times of periastron in an eccentric binary system, and the irregular shape of each eruptive event may be due to the instability of the LBV-like primary star.
03
Peculiar Kinematics of LMC LBVs
To determine if LMC LBVs have peculiar kinematics, we measured the systemic radial velocities of LMC LBVs, and compared them with the projected rotation curve velocity at LBV’s location. We find that the dispersion of LBVs (shown in blue) is more than twice the inferred velocity dispersion of RSGs (shown in red). We also find that 33% of LMC LBVs have radial velocities of more than 25 km s−1, while only 9% of RSG have such high velocities. This suggests that LBVs include more runaways than the population of RSGs, indicating that LBVs are preferentially kicked by a companion’s supernova explosion as compared to other evolved massive stars.
04
In the single-star scenario, the hypothesis is that most stars above ~30 solar mass pass through an LBV phase. However, the relative isolation of LBVs from O stars challenges this interpretation, and another hypothesis is emerging that the LBV phenomenon is the product of binary evolution. To test these hypotheses, we modeled the dissolution of young clusters and the separation between O stars and LBVs. We find that the single-star scenario is inconsistent with the observed LBV environments. If LBVs are single stars, then the lifetimes inferred from their luminosity and mass are far too short to be consistent with their isolation from O stars. This implies that LBVs are likely products of binary evolution.
The mean distance to the nearest neighbor versus drift velocity. Dashed lines represent the passive dissolution model and solid lines represent the observational data. We infer larger drift velocities for the later type O stars, implying that binary evolution and kicks may be important.