AAVSO: American Association of Variable Star Observers

New Intense Multiband Photometric Observations of the Hot Carbon Star V348 Sagittarii (Abstract)

Volume 47 number 1 (2019)

Franz-Josef Hambsch
Oude Bleken 12, Mol 2400, Belgium; hambsch@telenet.be
Christopher S. Jeffery
Armagh Observatory, College Hill, Armagh BT61 9DG, United Kingdom; csj@arm.ac.uk

Abstract

(Abstract only) V348 Sgr is one of four hot carbon-rich and hydrogen-deficient stars. It is also the central star of a planetary nebula with a strong stellar wind, an infrared dust excess, and a circumstellar dust shell. Since July 2014, near daily multi-band photometric observations have been obtained at the Remote Observatory Atacama Desert (ROAD) close to San Pedro de Atacama, Chile. Strong variations of the brightness of V348 Sgr have been observed, ranging from magnitude 19 to 11.2 in V band. No clear periodicity is discernible in the data. The observed light curve shows much more variation and on a much shorter time scale than that of R CrB, the prototype hydrogen deficient, carbon- and helium-rich star. The star becomes markedly redder during extinction phases as a consequence of obscuring dust. The particular challenge in this case is to understand what triggers the production of dust.