V1472 Aquilae
A triple star system with a short-period giant binary.
V1472 Aquilae is a triple star system in the equatorial constellation of Aquila. It is a variable star that ranges in brightness from 6.32 down to 6.51, and at its brightest is very faintly visible to the naked eye under excellent observing conditions. The system is located at a distance of approximately 780 light years from the Sun and is a high-velocity star system with a radial velocity of −112 km/s.
- Constellation
- Aquila
- Apparent magnitude range
- 6.32 – 6.51
- Distance
- approximately 780 light years
- Radial velocity
- −112 km/s
- Spectral type
- M2.5III
- Diameter
- 65 times the Sun
- Luminosity
- 650 times the Sun
Lore & Background
The binary nature of the main component was announced in 1982, found to be a single-lined spectroscopic binary with an orbital period of 198.7 days and an eccentricity of 0.05. At the time of its discovery, it was the shortest known binary period of any class M giant. The primary is an aging red giant with a stellar classification of M2.5III, having a diameter 65 times and luminosity 650 times that of the Sun. The star is a fast rotator with a projected rotational velocity of 10 km/s, possibly due to interaction with its companion.
The variability of this star was discovered from Hipparcos data and it was classified as a semiregular variable with a period of 100.3727039 days. However, a plot of the light curve better matches that of an eclipsing binary or ellipsoidal variable. The 198-day orbital period produces a light curve with a primary and secondary minimum which, together with possible variations due to ellipsoidal rotation, produces the observed semiregular 100-day photometric variation. Later observations show that it is less luminous than expected for a pulsating star with its amplitude, being more typical of ellipsoidal variables, and that it has a 200.05-day period with primary and secondary minima.
A co-moving companion some 4.0 magnitudes fainter than the primary lies at an angular separation not specified in the available data.
Reader's Guide
V1472 Aquilae is notable for its unusual variability, which was initially classified as semiregular but whose light curve better matches an eclipsing binary or ellipsoidal variable. The system's 198-day orbital period produces primary and secondary minima that, combined with possible ellipsoidal rotation effects, yield the observed 100-day photometric variation. Later observations indicate it is less luminous than expected for a pulsating star of its amplitude, aligning more closely with ellipsoidal variables, and reveal a 200.05-day period with primary and secondary minima. The primary star's rapid rotation, possibly due to tidal interaction with its companion, and its status as the shortest-period binary among class M giants at discovery, underscore the system's significance in studying binary evolution and variable star mechanisms. The presence of a co-moving companion adds to the system's complexity as a triple star system.
Frequently Asked Questions
What is V1472 Aquilae?
V1472 Aquilae is a variable triple star system located in the constellation Aquila. It contains a short-period giant binary pair, and its overall brightness fluctuates as the components interact.
How bright is V1472 Aquilae and can I see it?
Its apparent magnitude swings between 6.32 at peak and 6.51 at minimum. Under truly dark, clear skies, the system is just barely within naked-eye visibility at its brightest.
How far away is V1472 Aquilae?
The system sits roughly 780 light years from the Sun, placing it well beyond the nearby stellar neighborhood but still within the Milky Way's disk.
What type of star is V1472 Aquilae?
Its spectral classification is M2.5III, meaning it is a cool red giant. The star's diameter stretches to about 65 times that of the Sun.
Why do astronomers consider V1472 Aquilae a high-velocity star?
Its radial velocity measures −112 km/s, indicating it is moving toward the Solar System at a speed far above the typical local stellar population. This makes it a useful object for studying runaway or dynamically ejected stellar systems.
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