The Spatially Resolved Bipolar Nebula of Sakurai's Object
Abstract
Sakurai's object (V4334 Sgr), the final flash object discovered in the mid-1990s, underwent rapid cooling during the first decade of the 21st century becoming as faint as K ~ 25. This stage of evolution has ceased. Between observations in 2010 September and 2013 April V4334 Sgr brightened >2 mag to K = 14.2 and the effective temperature increased to ~590 K. AO images show a central source and two extended globules defining a 13° position angle. The globules span a spatial extent of ~0.''3 in 2013. This spatial extent is consistent with sizes derived from spectral energy distributions taken over the previous decade and a debris cloud expanding at 0.055 mas d-1 since late 1998. Near-simultaneous 0.85-2.5 μm spectra reveal helium lines attributed to a wind-interaction shock. The He I 1.0830 μm emission has a spectral width of ~1000 km s-1 and a spatial extent of ~1.''4. The helium shell is fragmented, spatially asymmetric, and five times larger than the dust debris cloud. [C I] and [N I] forbidden lines are present in the 1 μm region spectrum. The forbidden line spectrum is similar to that of proto-planetary nebulae. The [C I] 9850 Å line is spatially extended. The expansion velocity and change of angular size limit the distance to 2.1-3.7 kpc.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- April 2014
- DOI:
- 10.1088/0004-637X/785/2/146
- Bibcode:
- 2014ApJ...785..146H
- Keywords:
-
- infared: ISM;
- planetary nebulae: general;
- stars: evolution;
- stars: mass-loss;
- stars: AGB and post-AGB;
- stars: winds;
- outflows