First science with the Southern African Large Telescope: peering at the accreting polar caps of the eclipsing polar SDSS J015543.40+002807.2

Abstract

We describe briefly the properties of the recently completed Southern African Large Telescope (SALT), along with its first light imager SALTICAM. Using this instrument, we present 4.3 h of high‐speed unfiltered photometric observations of the eclipsing polar SDSS J015543.40+002807.2 with time‐resolution as short as 112 ms, the highest‐quality observations of this kind of any polar to date. The system was observed during its high‐luminosity state. Two accreting poles are clearly seen in the eclipse light curve. The binary system parameters have been constrained: the white dwarf mass is at the low end of the range expected for cataclysmic variables. Correlations between the positions of the accretion regions on or near the surface of the white dwarf and the binary system parameters were established. The sizes of the accretion regions and their relative movement from eclipse to eclipse were estimated: they are typically 4°–7° depending on the mass of the white dwarf. The potential of these observations will only fully be realized when low‐state data of the same kind are obtained and the contact phases of the eclipse of the white dwarf are measured.

Kinematics and Stellar Populations in Isolated Lenticular Galaxies

“…The observations were performed with the Robert Stobie Spectrograph (RSS; Kobulnicky et al 2003) at the SALT O'Donoghue et al 2006). The long-slit spectroscopy mode of the RSS was used with a 1.25 arcsec slit width for most observations.…”

Astrophysics in South Africa

“…The discovery paper of the first pulsating subdwarf O star (see above) contains the first published spectrum from SALT (Woudt et al, 2007). Several other modes of operation have been demonstrated (Romero-Colmenero et al, 2006). The flexible operation advantage has been made use of in producing the first very high time resolution photometry of rapid oscillations in an outbursting dwarf nova (Woudt & Warner, unpubl.…”

“…Also, the ability to concentrate on "time domain" astrophysics gives a specialized niche advantage. The first research paper to emerge from the new telescope immediately demonstrated the latter-light curves of an eclipsing 'polar ' at unprecedented time resolution, showing eclipse details of small luminous accreting regions on a white dwarf star (O'Donoghue et al, 2006; Figure 3). The discovery paper of the first pulsating subdwarf O star (see above) contains the first published spectrum from SALT (Woudt et al, 2007).…”

Search for Very High Energy Candidate Sources Among the Fermi Sources

“…The primary mirror, which consists of 91 segments, is at a fixed elevation of 53 • . The telescope hosts four instruments, namely: SALTICAM, a science imaging camera operating between 3200-9000 Å [6], the RSS (Robert Stobie Spectrograph) a low-to medium resolution spectrograph [7], the BVIT (Berkeley Visible Image Tube) a high-time resolution photometer [8], and the HRS (High Resolution Spectrograph). The most recent instrument, the HRS, started science observations in 2014.…”