Did Carinae's Weigelt Blobs Originate circa 1941?

Abstract

We report astrometric measurements of η Carinae's Weigelt blobs C and D (also known as speckle objects C and D) derived from observations with the Hubble Space Telescope Wide Field Planetary Camera 2. Using three epochs of data with a temporal baseline of 5.9 yr, we measure blob D's proper motion relative to the central star to be 4.4 ± 1.4 mas yr-1, implying a date of origin of 1934.1. Similarly, using two epochs with a 1.7 yr baseline, we measure blob C's relative proper motion to be 3.8 ± 5.6 mas yr-1, indicating a probability of ejection after 1910 of ≈60%; we view this as confirming the more accurate blob D results (assuming coevality), with a combined post-1910 ejection indicated at a ≈90% confidence level. The blob D date roughly coincides with the sudden brightening of the central star observed in 1941 and provides a possible explanation for the onset of certain narrow spectral features, associated with the Weigelt blobs, that have been observed only since the mid-1940s. We propose that the ejection of Weigelt blobs C and D was related to this 1941 event.