we propose to take advantage of the opportunity to witness the development of a star undergoing a late he-flash right now. several months ago an exciting new object that most likely belongs to this rare class has been discovered (sakurai.s object; see iau circ. 6322). originally classified as a slow nova it now has to be considered as a star undergoing its late he-flash at the moment. an old (30 arcsec) planetary nebula (pn) has been discovered in narrow-band images taken in halpha and [oiii]. the spectrum of sakurai.s object resembles that of an f-type supergiant, albeit with anaoously strong lines of c, n and o and weak h-balmer lines (duerbeck & benetti, 1996, apj 468, l111; kerber et al. 1996 proc. iau symp. 180 on planetary nebulae, in press). the only other examples in historical times are v605aql (a 58) in 1919, and possibly fg sag. to take full advantage of such an event taking place, we have initiated a coordinated monitoring effort with partners in chile, south africa, and new zealand. talks are underway with additional colleagues in brazil and australia as well as colleagues involved in denis.- it should be noted that such an object is not a curiosity in the context of stellar evolution, but a process that should be experienced by 10 to 20% of all low-mass stars (iben et al., 1983, apj 264, 605). observations with iso will be done with phot. we request two observations of sakurai.s object: one as soon as possible and the second late in the mission in order to assess the development of the object. in particular the question if and when dust is beginning to form can be addressed by these measurements in combination with our ground-based network. calculations of the exposure times have been done based on high precision ijks photometry derived from denis survey data. for the second observation updated input will be provided to account for any developments in brightness. this proposal has to be regarded... as a valuable supplement of our iso projects on dust in pne (rweinber.dibapne, rweinber.eoddipne), particularly of dust in born-again planetary nebulae.
Instrument
CAM01
Temporal Coverage
1997-02-25T07:17:17Z/1998-02-27T10:32:06Z
Version
1.0
Mission Description
The Infrared Space Observatory (ISO) was the world's first true orbiting infrared observatory. Equipped with four highly-sophisticated and versatile scientific instruments, it was launched by Ariane in November 1995 and provided astronomers world-wide with a facility of unprecedented sensitivity and capabilities for a detailed exploration of the Universe at infrared wavelengths.
European Space Agency, 1999, Sakurai.S Object: A New Born-Again Nucleus Of A Planetary Nebula, 1.0, European Space Agency, https://doi.org/10.5270/esa-nr28v38
