2008A&A...480..187D -
Astronomy and Astrophysics, volume 480, 187-191 (2008/3-2)
The pulsating λ Bootis star 15 Andromedae: results from a three-site photometry campaign.
DOROKHOVA T.N., HANDLER G., DOROKHOV N.I., RODRIGUEZ E. and UDOVICHENKO S.N.
Abstract (from CDS):
The λ Bootis stars are a chemically peculiar subgroup of main sequence A/F stars. Several of these fall into the instability strip of the δ Scuti stars and the whole spectroscopic group shows a high incidence of pulsational variability. We investigated the pulsational behaviour of the λ Bootis star 15 And (HD 221756) to determine as many intrinsic mode frequencies as possible for asteroseismic applications. The star was included as a secondary target for three telescopes during a campaign devoted to the β Cep stars 12 and 16 Lac, due to its proximity to these targets. 302.8h of time-resolved photometry spanning 161.2 d were acquired and analyzed. Our frequency analysis revealed f1=24.7887(2)c/d as the main pulsation frequency, with an amplitude of only 1.9(1)mmag. The residual periodogram suggests the presence of additional frequencies in an interval from 20 to 25c/d, with very low amplitudes. We succeeded in detecting a second frequency f2=22.2580(9) with an amplitude of 0.6(1)mmag. Low-frequency light variations of the comparison star HD 220575 were revealed as well. The pulsational behaviour of 15 And as a typical λ Boo-type star is compared with that of δ Scuti stars with normal abundances and with metallic-line δ Scuti stars. We discuss the value of λ Boo stars in understanding accretion and mixing in pulsating stars. The difficulties in the selection of reliable comparison stars for such high-precision research are pointed out.
Abstract Copyright:
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Journal keyword(s):
stars: chemically peculiar - stars: individual: HD 221756 - stars: individual: HD 220575 - stars: oscillations - stars: variables: δ Scuti
VizieR on-line data:
<Available at CDS (J/A+A/480/187): table2.dat table3.dat table4.dat>
Simbad objects:
8
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