Infrared Spectroscopy of the Unusual Slow Nova V5558 Sagittarii
Abstract
V5558 Sgr (Nova Sagittarii 2007) was a peculiar, Fe II-type nova that showed a 3-month rise to maximum brightness followed by a slow decline punctuated by episodic outbursts that produced local maxima in the light curve. Supplementing the optical spectra of Poggiani [2008,New Astronomy, 13, 557-562], we present 7 epochs of infrared (0.8-5 microns) observations (and two sets of optical measurements) that span the first 15 months of activity. These spectra reveal a remarkable hydrogen line spectrum that include detections of five different series of H I lines, the disappearance of P-cygni profiles on almost all of these features, the emergence of a strong Fe II features, and the late appearance of He II features with 2-3 times the breadth of the lower excitation lines. The emission lines were narrow initially (FWHM 300 km/sec) and less blended than those of a typical novae. This facilitated their identification and study, as did the small amount of reddening [E(B-V)=0.8] along the line-of-sight to V5558 Sgr. This low extinction is unusual for a nova at a Galactic latitude of 0.22 degrees, suggesting that V5558 Sgr is comparatively nearby. Other charactgeristics of this unusual nova include the weakness of the lines of neutral oxygen and the absence of dust formation.
- Publication:
-
American Astronomical Society Meeting Abstracts #214
- Pub Date:
- May 2009
- Bibcode:
- 2009AAS...21442806R