Delta Scuti
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Delta Scuti, Latinized from δ Scuti, is a variable star in the southern constellation Scutum. With an apparent visual magnitude that fluctuates around 4.72,[5] it is the fifth-brightest star in this small and otherwise undistinguished constellation. Analysis of the parallax measurements place this star at a distance of about Script error: No such module "convert". from Earth.[2] It is drifting closer with a radial velocity of −43 km/s.[2]
Variability
In 1900, William W. Campbell and William H. Wright used the Mills spectrograph at the Lick Observatory to determine that this star has a variable radial velocity.[11] The Script error: No such module "convert". period of this variability as well as 0.2 magnitude changes in luminosity demonstrated in 1935 that the variability was intrinsic, rather than being the result of a spectroscopic binary.[12] In 1938, a secondary period was discovered and a pulsation theory was proposed to model the variation.[13] Since then, observation of Delta Scuti has shown that it pulsates in multiple discrete radial and non-radial modes. The strongest mode has a frequency of 59.731 μHz, the next strongest has a frequency of 61.936 μHz, and so forth, with a total of eight different frequency modes now modeled.[14]
Delta Scuti is the prototype of the Delta Scuti type variable stars. It is a high-amplitude δ Scuti type pulsator with light variations of about 0.19 magnitudes (V).[15] The peculiar chemical abundances of this star are similar to those of Am stars.[8] It has a stellar classification of F2 IIIp,[4] matching an F-type giant star. Delta Scuti has two times the mass and between 4.07 and 4.25 times the radius of the Sun. It is approximately one billion year old[7] and is spinning with a projected rotational velocity of 25.5 km/s.[8] The radius of Delta Scuti changes at 0.3 to 0.9 percent at each pulsation cycle.[7] On average, the star is radiating 40 times the luminosity of the Sun from its photosphere at an effective temperature of 7,000 K.[7]
Space velocity
The space velocity components of this star in the galactic coordinate system are [U, V, W] = [−42, −17, −1] km·s−1. It is following an orbit through the Milky Way galaxy that has an eccentricity of 0.11, carrying it as close as Script error: No such module "convert". to, and as far as Script error: No such module "convert". from the Galactic Center.[6] If Delta Scuti maintains its current movement and brightness, it will pass within 10 light-years of the Solar System,[16] becoming the brightest star in the sky between Script error: No such module "val". and Script error: No such module "val".. It will reach an apparent magnitude of −1.84, brighter than the current −1.46 of Sirius.[17][18]
Optical companions
This star has two optical companions. The first is a +12.2 magnitude star that is 15.2 arcseconds from Delta Scuti. The second is a +9.2 magnitude star that is 53 arcseconds away.[19] Both are distant background stars unrelated to Delta Scuti.[20]
Nomenclature
Flamsteed did not recognise the constellation Scutum and included several of its stars in Aquila. δ Scuti was catalogued as 2 Aquilae. The Bayer designation δ was assigned by Gould rather than Bayer.[21]
References
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- ↑ a b c d e f g Template:Cite Gaia DR3
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- ↑ Script error: No such module "Citation/CS1". Listed as 2 Scuti on p. 256.
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- ↑ Sky and Telescope, April 1998 (p60), based on computations from Hipparcos mission data.
- ↑ Script error: No such module "Citation/CS1". – based on computations from HIPPARCOS data. (The calculations exclude stars whose distance or proper motion is uncertain.) PDFScript error: No such module "Unsubst".Template:Cbignore
- ↑ Script error: No such module "citation/CS1".
- ↑ Template:Cite Gaia DR3
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