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The mode identification and physical parameter determination of the delta Scuti star SAO 16394
The star SAO 16394 was observed with the 85 cm telescope at the XinglongStation of Beijing Astronomical Observatory of China from 8 to 17 April1997 and identified as a new delta Scuti star in 1998. In order todetermine its frequencies and pulsation modes accurately it was observedat the Xinglong Station in 1998 and 1999, and at the Sierra NevadaObservatory (Spain) in 1999. Period analyses were made for our data set(1997) and the data set (1997-1999). From the combined data set(1997-1999), the values of two frequencies are: 16.8493 and 23.0613cd-1. From our photoelectric observations, we obtained twophysical parameters of SAO 16394: log L/Lsun = 1.16, logTeff = 3.92. We calculated the evolution sequences of stellarmodels with 1.00-2.00 solar mass in steps of 0.05Msun and 8physical parameters of each evolutionary phase. We suggest that theevolutionary sequence of the 1.85 Msun model might representthe evolutionary sequence of SAO 16394. The 30th evolutionary phase ofthe evolutionary sequence of the model with 1.85 Msun mightrepresent the current location of SAO 16394. Depending on the Q values(Q1 = 0.0336 day, Q2 = 0.0246 day) and frequencyratio f1/f2 = 0.7306 we identify f1(16.8493 cd-1) as the radial fundamental mode, f2(23.0613 cd-1) as its first overtone.
| A New delta Scuti Variable Star - SAO 16394
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| The Delta Scuti star HD 127759
The results are reported of six nights of V-band observations of thenewly discovered Delta Scuti variable HD 127759 during April 3-21, 1991and its Stromgren uvby(beta) photometry. The period analysis indicatesthat HD 127759 is a single-sine frequency-dominant pulsation variablewith a frequency of 14.78626 cycle/d and an amplitude of 0.0199 m. Thetimes of maximum are given. The star is located at the blue edge of theDelta Scuti variable instability strip, with T(eff) about 8400 K andM(V) about 0.93 m.
| HD 127759: a New delta Scuti Variable
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| HD 127759 is possibly a short period variable.
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| The distance to the high-velocity clouds - Mass infall and galactic disk formation
The high-velocity neutral hydrogen complex C in optical (Ca K)absorption against stars at distances of 1-2 kpc has been detected,confirming a previous tentative detection and placing an upper limit onthe distance to this complex. A similar (though as yet more uncertain)limit is placed to the distance to complex A. No complex is detected inabsorption against any nearby star, effectively ruling out models inwhich the clouds are formed by supershells in the local disk. If thesedistances are representative of the bulk of the high-velocity clouds,the local mass infall rate is 6 x 10 to the -9th solar mass/sq pc/yr,which would supply the disk column density in 10 billion yr. The cloudslie above the bulk of the disk, and it is shown how they may be used tomeasure the pressure of the halo and to place an upper bound on themetagalactic UV flux.
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