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29 frequencies for the δ Scuti variable BI CMi: the 1997-2000 multisite campaigns
A multisite campaign of BI CMi was carried out with excellent frequencyresolution and high photometric accuracy from 1997 to 2000, includingtwo long observing seasons. 29 pulsation frequencies could be extractedfrom the 1024h (177 nights) of photometry used. The detected frequenciesinclude 20 pulsation modes in the main pulsation frequency range from4.8 to 13.0cycled-1 (55 to 150μHz), eight linearcombinations of these frequencies, and a very low frequency at1.66cycled-1. Since the value of the low frequency at1.66cycled-1 cannot be identified with a linear combinationof other frequencies, g-mode pulsation is suspected, but rotationalmodulation of abundance spots cannot be ruled out. BI CMi, which issituated near the cool edge of the classical instability strip, may beboth a δ Scuti and a γ Doradus star. Another outstandingproperty of BI CMi is the presence of a number of close frequency pairsin the power spectrum with separations as small as0.01cycled-1. A rotational velocity ofvsini=76+/-1kms-1 was determined from a high-dispersionspectrum. From phase differences, the dominant modes can be identifiedwith l values from 0 to 2. The spectral type and evolutionary status ofBI CMi are examined.
| New uvbybeta photometry of stars of ``astrophysical interest''
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| The delta Scuti star BI Canis Minoris (identically equals HD 66853): Pulsational behavior and a critical discussion of physical parameter determination
A two site photometric campaign on the delta Scuti star BI CMi (2302 Vobservations over 16 nights) has allowed us to detect unambiguously fourpulsation frequencies nul = 8.246, nu2 = 8.865,nu3 = 7.433 and nu4 = 8.515 c/d) with amplitudesbetween 22 and 5 mmag. The data also show the presence of the nonlinearcoupling term nu1 + nu2, the 2 nu1 termand the possible presence of two other frequencies with amplitudes of2-3 mmag. Other components with further smaller amplitudes are probablypresent, but the data do not allow reliable identifications. We discussthe identification of the pulsation modes in term of nonradical p modes,and we also point out the uncertainties on these identificationassociated to the physical parameter estimates. The possiblemicrovariability of HD 67028, one of the two comparison stars, is alsodiscussed.
| A New Variable Star BD +2 1867
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| Takýmyýldýz: | Kucuk Kopek |
| Sað Açýklýk: | 08h05m25.30s |
| Yükselim: | +01°33'13.2" |
| Görünürdeki Parlaklýk: | 9.201 |
| özdevim Sað Açýklýk: | -15.7 |
| özdevim Yükselim: | -11.5 |
| B-T magnitude: | 9.58 |
| V-T magnitude: | 9.233 |
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