Delta Scuti

Database links to δ Scuti

Star δ Scuti
AladinLite
Observation dates equinox :  J2000.0 , epoch : J2000.0
Constellation	sign
Right ascension	18 h 42 m 16.43 s
declination	-09 ° 03 ′ 9.2 ″
Apparent brightness	4.71 (4.6 to 4.79) mag
Typing
B − V color index	+0.35
U − B color index	+0.16
R − I index	+0.19
Spectral class	F3 IIIp
Variable star type	DSCT
Astrometry
Radial velocity	(−45.1 ± 0.6) km / s
parallax	(16.36 ± 0.20)  mas
distance	(199 ± 3)  ly (61.1 ± 0.8)  pc
Visual absolute brightness M vis	approx. +0.7 mag
Proper movement
Rec. Share:	(+7.18 ± 0.32)  mas / a
Dec. portion:	(+2.00 ± 0.27)  mas / a
Physical Properties
Effective temperature	7000  K
Other names and catalog entries
Bayer name δ Scuti Flamsteed name 2 scuti Bonn survey BD −9 ° 4796 Bright Star Catalog HR 7020 [1] Henry Draper Catalog HD 172748 [2] Hipparcos catalog HIP 91726 [3] SAO catalog SAO 142515 [4] Tycho catalog TYC 5692-2505-1 [5] 2MASS catalog 2MASS J18421642-0903092 [6] Other names FK5  1486
annotation
↑ estimated from apparent brightness and distance

Delta Scuti (δ Sct / δ Scuti) is about 200  light years from the Earth distant giant star of spectral class F in the constellation shield . Delta Scuti is the prototype and namesake of the Delta Scuti stars , a subclass of the pulsation-variable stars .

discovery

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

With the help of the Mills spectrograph, the two of them measured random samples of the radial velocity of various moderately bright stars in 1900 and found among them some whose radial velocity varied with time. In one of them, known at the time as "2 Scuti", they saw changes in its radial velocity with amplitudes of several kilometers per second.

More than 30 years later, Edward Fath and Attilio Colacevich re-examined this object and published a brief summary of their findings in the Publications of the Astronomical Society of the Pacific . Fath conducted a photometric study while Colacevich used the Mills spectrograph to more accurately measure the amplitude of the star's radial velocity.

Both found a period of 0.1937 per day and Colacevich claimed that with such a combination of the amplitude and period values ​​of the radial velocity, it could not be a spectroscopic binary star . Fath also noted photometric amplitude variations in his writings from 1935 and in 1937 even several periods were discovered within the photometric data. On the basis of this period variability and the changes in luminosity of 0.2 magnitudes, they demonstrated in 1935 that this had to be an intrinsic variability, that is, that the change in luminosity of the star has its origin "coming from within" and not was the result of a spectroscopic binary star.

properties

In 1938 the Harvard professor Theodore Sterne investigated whether radial pulsations could possibly be responsible for the multiple periods that were observed in this star. A second period was discovered and a theory was proposed to describe the pulsation of this variant. According to this theory, the fluctuations in brightness can be traced back to an alternating expansion and contraction of the stellar atmosphere.

Since then, observing Delta Scuti has shown 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. A total of eight different frequencies could be determined at this star.

The brightness fluctuations of Delta Scuti extend over an amplitude of about 0.2  mag , the two dominant periods of oscillation are 4.65 and 4.48 hours. The others are given with values ​​of 2.79, 2.28, 2.89 and 20.11 hours. The star also shows abnormalities in the metal frequency , which are similar to those of Am stars.

He has two optical companions. The first is a +12.2 star located 15.2  arc seconds from Delta Scuti. The second is a star of magnitude +9.2, located 53 arc seconds from the main star.

Web links

• http://stars.astro.illinois.edu/sow/deltasct.html

Individual evidence

1. ↑ ^{a b c d} del Sct. In: SIMBAD . Center de Données astronomiques de Strasbourg , accessed on October 31, 2018 . 
2. ↑ ^{a b c} del Sct. In: VSX. AAVSO, accessed October 31, 2018 . 
3. ↑ ^{a b} Johnson, HL; Iriarte, B .; Mitchell, RI; Wisniewskj, WZ: UBVRIJKL photometry of the bright stars . In: Communications of the Lunar and Planetary Laboratory . 4, No. 99, 1966. bibcode : 1966CoLPL ... 4 ... 99J .
4. ↑ Bright Star Catalog
5. ↑ Pulkovo radial velocities for 35493 HIP stars
6. ↑ ^{a b} Yushchenko, A., et al .: The chemical composition of δ Scuti . In: Monthly Notices of the Royal Astronomical Society . 359, No. 55, May 2005, pp. 865-873. doi : 10.1111 / j.1365-2966.2005.08921.x .
7. ↑ Campbell, WW; Wright, WH: A list of nine stars whose velocities in the line of sight are variable. . In: Astrophysical Journal . 12, 1900, pp. 254-257. doi : 10.1086 / 140765 . Listed as 2 Scuti on page 256.
8. ↑ Colacevich, A .: On the Variable Radial Velocity of δ Scuti . In: Publications of the Astronomical Society of the Pacific . 47, No. 278, August 1935, pp. 231-232. doi : 10.1086 / 124599 .
9. ^ Theodore Eugene Stars: The Secondary Variation of δ Scuti . In: Astrophysical Journal . 87, August, pp. 133-134.
10. ↑ TE Stars: The Secondary Variation of δ Scuti . In: Astrophysical Journal . 87, March 1938, pp. 133-150. doi : 10.1086 / 143913 .
11. ↑ Templeton, Matthew R., et al .: A New Pulsation Spectrum and Asteroseismology of delta Scuti . In: The Astronomical Journal . 114, October 1997, pp. 1592-1601. doi : 10.1086 / 118590 .
12. ↑ http://www.daviddarling.info/encyclopedia/D/Delta_Scuti_star.html
13. ^ Robert Burnham: Burnham's celestial handbook: an observer's guide to the universe beyond the solar system , Volume 3.Courier Dover Publications, 1978, ISBN 0486236730 , p. 1746.