We present the results on the photometric and spectroscopic monitoring of a
luminous Ap star HD103498. The time-series photometric observations were
carried out on 17 nights using three-channel fast photometer attached to the
1.04-m optical telescope at ARIES, Nainital. The photometric data of five
nights of year 2007 show clear signature of 15-min periodicity. However, the
follow-up observations during 2007--2009 could not repeated any such
periodicity. To confirm the photometric light variations, the time-series
spectroscopic observations were carried out with the 2.56-m Nordic Optical
Telescope (NOT) at La Palma on February 2, 2009. Any radial velocity variations
were absent in this data set which is in full agreement with the photometric
observations taken near the same night. Model atmosphere and abundance analysis
of HD103498 show that the star is evolved from the Main Sequence and its
atmospheric abundances are similar to two other evolved Ap stars HD133792 and
HD204411: large overabundances of Si, Cr, and Fe and moderate overabundances of
the rare-earth elements. These chemical properties and a higher effective
temperature distinguish HD103498 from any known roAp star.Comment: 8 Figures, 2 Tables, 9 Pages, Accepted for publication in MNRA