Epoch J2000 Equinox J2000
|Right ascension||18h 42m 16.422137s|
|Declination||−09° 03′ 09.19206″|
|Apparent magnitude (V)||4.72|
|Spectral type||F2 IIIp|
|U−B color index||+0.16|
|B−V color index||+0.35|
|Variable type||δ Sct|
|Radial velocity (Rv)||−44.8 km/s|
|Proper motion (μ)||RA: 9.21 mas/yr
Dec.: 0.82 mas/yr
|Parallax (π)||16.11 ± 0.31 mas|
|Distance||202 ± 4 ly
(62 ± 1 pc)
|Absolute magnitude (MV)||±0.040.72|
|Surface gravity (log g)||3.5 cgs|
|Metallicity [Fe/H]||0.41 dex|
|Rotational velocity (v sin i)||25.5 km/s|
Delta Scuti (δ Sct, δ Scuti) is a giant star in the southern constellation Scutum. With an apparent visual magnitude of 4.72, it is the fifth brightest star in this small and otherwise undistinguished constellation. Analysis of the parallax measurements made during the Hipparcos mission place this star at a distance of about 202 light-years (62 parsecs) from Earth. 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 0.15 minutes. The peculiar chemical abundances of this star are similar to those of Am stars.
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. The 77-day 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 0.193spectroscopic binary. In 1938, a secondary period was discovered and a pulsation theory was proposed to model the variation. 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.
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 22.31 kly (6.84 kpc) to, and as far as 27.59 kly (8.46 kpc) from the galactic center. If Delta Scuti maintains its current movement and brightness, it will pass within 10 light years of the solar system, becoming the brightest star in the sky between 150000 and 1330000 CE. It will reach an apparent magnitude of -1.84, brighter than the current -1.46 of 1Sirius.
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.
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