Delta Scuti

Delta Scuti ( δ Sct / δ Scuti ) is a roughly 187 light years from Earth distant giant star of spectral type F in the constellation sign. Delta Scuti is the prototype and namesake of the Delta Scuti stars, a subclass of pulsating variables stars.

Discovery

The discovery of Delta Scuti goes back to the scientist William W. Campbell and William H. Wright of the Lick Observatory.

With the help of the Mills spectrograph, the two measured in 1900 randomly the radial velocity of several moderately bright stars and found among them some whose radial velocities varied with time. In one of them, which was described at that time as " 2 Scuti " they were able to observe the change in its radial velocity with amplitudes of several kilometers per second.

More than 30 years later examined Edward Fath and Attilio Colacevich this object again and published a short summary of their findings in Publications of the Astronomical Society of the Pacific. Fath led there by a photometric study, while Colacevich used the Mills spectrograph to measure the amplitude of the radial velocity of the star in more detail.

Both found a period of 0.1937 per day and Colacevich claimed that it could act in such a combination of amplitude and period value of the radial velocity, not a spectroscopic binary. Fath presented in his writings from 1935 also photometric amplitude variations firmly and in 1937 it was discovered within the photometric data even several periods. From this period variability and changes in the luminosity of 0.2 mag they showed in 1935 that there had to be an intrinsic variability in this case, so that the luminosity of the star change its origin " coming from within" and has just not the result of a spectroscopic binary was.

Properties

In 1938, studied at Harvard Professor Theodore stars, whether any radial pulsations could be responsible for the multiple periods that were observed in this star. Here, a second period was discovered and it was a theory proposed to describe the pulsation of this variant. According to this theory, the brightness fluctuations in an alternating expansion and contraction of the atmosphere due rating.

Since then, it has been shown for the observation of Delta Scuti that the star pulsates in several discrete radial and non-radial periods. The strongest period has a frequency of 59.731 μHz the next strongest a value of 61.936 μHz and so on. Altogether eight different frequencies are determined for this star.

The brightness variations of the delta Scuti have an amplitude of about 0.2 may be on the two dominant oscillation period be 4.65 and 4.48 hours. The further be specified with values ​​of 2.79, 2.28, 2.89 and 20.11 hours. The star also shows abnormalities in the metal abundance, which are similar to those of Am stars.

It has two optical companion. The first is a star of brightness 12.2, which is located 15.2 arcsec of Delta Scuti. The second is a star of magnitude 9.2, which is located at a distance of 53 arc seconds to the main star.