COMMISSION 27 AND 42 OF THE IAU INFORMATION BULLETIN ON VARIABLE STARS Number 3832 Konkoly Observatory Budapest 19 January 1993 HU ISSN 0374 - 0676 HR 8851=HD 219586 IS A DELTA SCUTI STAR Here we announce that HR 8851 is possibly a Delta Scuti star which is newly discovered during the two night observation on December 23 and 25, 1992 at Xinglong Station, Beijing Astronomical Observatory. The observation was performed with the 60 cm reflector in V band. HR 8918=HD 220974 and HD 220841 were chosen as the comparison star and check star, respectively. Some information on these three stars resorted from the newest version of the Bright Star Catalogue is given in Table 1. The weather conditions on these two nights were quite good and the observational log is listed in Table 2. The V band data of HR 8851 observed on Dec. 23 and 25 are listed in Table 3 and the lightcurves of HR 8851 with those of HD 220841 are plotted in Fig. 1. The lightcurves suggest that the full amplitude of the light variation exceeds 0.05 mag. and the periodicity is complex. [FIGURE 1] Figure 1. The lightcurves of HR 8851 (+) and those of the check star HD 220841 for comparison (*) Table 1. Information from The Bright Star Catalogue V B-V U-B spectral type v sin i radial velocity (rotational) HR 8851 5.56 0.24 0.12 F0IV 140 km/s -12 km/s HR 8918 5.6 0.19? A6IV 115 km/s -3 km/s HD 220841 6.7 A2 Table 2. Observation log weather begin end time span number of obs. accuracy (UT) (UT) (hour) (mag) Dec.23 Excellent 11:05:09 14:44:58 3.66 26 0.0059 Dec.25 Good 9:58:11 15:16:35 5.31 39 0.0055 Table 3. Observational data of HR 8851 JDH V JDH V JDH V JDH V +2448900 +2448900 +2448900 +2448900 79.96457 -.595 80.07706 -.549 81.95451 -.571 82.07487 -.599 79.97026 -.596 80.08121 -.553 81.96244 -.561 82.07866 -.602 79.97554 -.590 80.08543 -.550 81.96692 -.552 82.08284 -.598 79.98239 -.585 80.08971 -.553 81.97136 -.558 82.08636 -.587 79.98781 -.578 80.09484 -.550 81.97523 -.555 82.09131 -.596 79.99339 -.576 80.09965 -.557 81.97952 -.559 82.09577 -.612 79.99962 -.572 80.10448 -.565 81.98348 -.553 82.09962 -.604 80.00722 -.567 80.10912 -.565 81.98738 -.555 82.10790 -.607 80.01243 -.569 80.11341 -.562 81.99180 -.555 82.11236 -.589 80.02519 -.573 81.91796 -.570 81.99793 -.557 82.11646 -.595 80.02591 -.570 81.92313 -.568 82.00230 -.558 82.12102 -.590 80.03146 -.572 81.92894 -.571 82.01723 -.567 82.12596 -.587 80.03768 -.569 81.93287 -.563 82.02237 -.579 82.13137 -.588 80.05375 -.552 81.93672 -.572 82.02698 -.567 82.13547 -.583 80.06328 -.549 81.94047 -.568 82.03130 -.566 80.06763 -.547 81.94428 -.563 82.03595 -.568 80.07256 -.546 81.94849 -.567 82.03966 -.576 *Note: The V band values are those of VAR-0.5x(comparison+check) We used the periodogram method to estimate the variation and get two periods of P_1=0.2717d+-0.0007 and P_2=0.0734d+-0.0002 with amplitudes of 0.021m and 0.006m+-0.001, respectively. The phase diagram of P_1 is shown in Fig. 2. We can see that the variation trend is fitted well by P_1, but some parts are not good enough because of the existence of P_2. Considering the limit of the data quantity (only two night observation), we cannot confirm the second period P_2 but the first one is undoubted. Further observations are needed to improve the accuracy of the period determination and find the small amplitude periods so that we can identify the pulsation mode of the Delta Scuti star HR 8851. [FIGURE 2] Figure 2. The phase diagram of the variation in HR 8851 for the period of 0.2717d We searched the newest edition of General Catalogue of Variable Stars and the catalogue of Delta Scuti stars (Lopez de Coca et al., 1990). We also searched Abstracts of A&A until 1991 and Astronomical Abstracts Database until October, 1992 in Astronomical Data Center of Beijing Astronomical Observatory. No reports about the photometric variation of HR 8851 were found, even a piece of information on this star. So we conclude that this is the first time the pulsation was found in HR 8851. Finally we note that HR 8851 is announced to be a spectroscopic binary system by the Bright Star Catalogue, but no elements of the orbit are given. So the possibility of the shallow eclipse between the primary star and the secondary star should be taken into account. Anyway, we tend to think that the variation is caused by the pulsation of the star instead of the eclipse because the spectral type, the time scale and the amplitude of the photometric variation for HR 8851 indicate that this star is a Delta Scuti star candidate. HAO JINXIN HUANG LIN Beijing Astronomical Observatory, Chinese Academy of Sciences Beijing, China 100080 Reference: Lopez de Coca, P., Rolland, A., Rodriguez, E. and Garrido, R., 1990, Astron. Astrophys. Suppl. Ser., 83, 51. [BIBCODE 1990A&AS...83...51L ]