LoTr 1

Lore & Background

LoTr 1 was discovered in 1980 by astronomers A.J. Longmore and S.B. Tritton using the UK Schmidt Telescope, as part of a group of 12 planetary nebulae cataloged under the LoTr Catalog. The nebula is bubble-shaped and elliptical, with a binary central star system. Its nucleus has similar properties to those found in Abell 35 and LoTr 5, where the central star consists of a giant star and a hot companion detected by the International Ultraviolet Explorer.

The nebula features a central inner shell with an angular diameter of 47 ± 4 arcseconds and an expansion age of approximately 17,000 years. It also has an outer shell with a more irregular shape, a diameter of 4 ± 26 arcseconds, and an expansion age of about 35,000 years. Both shells have an estimated expansion velocity of ~25 ± 4 km/s. The two slightly elongated shells possess different spatial orientations, indicating separate historical mass-transfer or ejection episodes from binary interaction. The nebula is significantly brighter in ionized oxygen [O III] wavelengths compared to other emissions. The double-peaked Hα emission lines remain a mystery, but have been hypothesized to come from an active accretion disk.

Reader's Guide

LoTr 1 is significant as a planetary nebula with a binary central star system, providing a laboratory for studying the effects of binary interaction on nebular morphology and evolution. The presence of two shells with different spatial orientations and expansion ages suggests distinct mass-transfer or ejection episodes, likely driven by the binary system. The nebula's brightness in ionized oxygen [O III] wavelengths highlights its chemical and physical conditions. The double-peaked Hα emission lines, though unexplained, point to possible accretion disk activity, linking LoTr 1 to broader phenomena in binary star evolution. Its discovery alongside 11 other nebulae in the LoTr Catalog underscores its role in expanding the known population of such objects. The central star's properties, shared with Abell 35 and LoTr 5, reinforce the importance of binary systems in shaping planetary nebulae. The nebula's legacy lies in its contribution to understanding mass transfer, shell formation, and the late stages of stellar evolution in binary systems.

Did You Know?

• The nebula has two shells with different spatial orientations, indicating separate mass-transfer or ejection episodes.
• The double-peaked Hα emission lines in LoTr 1 remain a mystery but are hypothesized to come from an active accretion disk.