BX Andromedae
Eclipsing binary in Andromeda with a 14.6-hour cycle.
BX Andromedae (BX And) is an eclipsing binary star in the constellation Andromeda, classified as a Beta Lyrae variable. Its maximum apparent visual magnitude is 8.87, and it exhibits a primary and secondary eclipse within a cycle of approximately 14.6 hours.
- Maximum apparent visual magnitude
- 8.87
- Primary eclipse magnitude
- 9.53
- Secondary eclipse magnitude
- 9.12
- Period approx hours
- 14.6
- Spectral type
- F2V
- Visual companion magnitude
- 10.85
- Visual companion separation arcseconds
- 20
- Visual companion mass solar
- 1.04
Lore & Background
The variability of BX Andromedae was first reported by A. Soloviev in 1945, who suspected it was an eclipsing binary but could not determine its period. The period was first measured in 1951 by Joseph Ashbrook. As a Beta Lyrae variable, the system shows a primary minimum when the more luminous star is eclipsed and a secondary minimum when the less luminous star is eclipsed, with brightness changing smoothly so there is no distinct onset or end of eclipses.
The two stars orbit so closely that they are distorted into ellipsoidal shapes. The spectrum of the individual stars has not been separated; the combined spectrum is type F2V. Physical parameters such as mass, radius, and temperature are inferred from the light curve. The system may be quadruple: slight orbital period variations suggest a third faint body with an orbital period of 62 years, and there is a visual companion star TYC 2833-53-1 of magnitude 10.85 located 20 arcseconds away, sharing common proper motion and a compatible parallax distance, with an estimated mass of 1.04 solar masses.
Reader's Guide
BX Andromedae is notable as a Beta Lyrae variable, a class of close eclipsing binaries where the components are tidally distorted and the light curve varies smoothly. Its discovery by Soloviev in 1945 and period determination by Ashbrook in 1951 mark early steps in understanding such systems. The star's significance lies in its potential as a quadruple system: the observed orbital period variations hint at a third body with a 62-year orbit, and the visual companion TYC 2833-53-1, with common proper motion and compatible distance, may be physically bound. This makes BX Andromedae a candidate for studying multiple-star dynamics and mass transfer in close binaries. The inability to separate the spectra of the two main stars underscores the challenge of analyzing such systems, where physical parameters must be inferred from light curves. Its legacy includes contributing to knowledge of Beta Lyrae variables and the prevalence of multiple-star systems among eclipsing binaries.
Did You Know?
- BX Andromedae was first reported as variable by A. Soloviev in 1945.
- Its period was first measured by Joseph Ashbrook in 1951.
- The system may be quadruple, with a possible third body having a 62-year orbital period.
- A visual companion, TYC 2833-53-1, lies 20 arcseconds away with common proper motion.
Frequently Asked Questions
What is BX Andromedae?
BX Andromedae is an eclipsing binary star system located in the constellation Andromeda. It belongs to the Beta Lyrae class of variables, meaning its two stars partially overlap during each eclipse rather than fully covering one another.
How long is BX Andromedae's eclipse cycle?
The pair completes one full primary-plus-secondary eclipse cycle in roughly 14.6 hours. That means observers can, in principle, see both the deeper primary dip and the shallower secondary dip within a single night.
How bright does BX Andromedae appear from Earth?
At maximum light the system reaches an apparent visual magnitude of 8.87, which is well beyond naked-eye visibility. During the primary eclipse it dims to about 9.53, and the secondary eclipse brings it down to roughly 9.12.
What spectral type is BX Andromedae?
The system is classified as F2V, indicating a hot, yellow-white main-sequence star as the dominant component. A fainter visual companion of magnitude 10.85 is also catalogued nearby, though it does not participate in the eclipses.
Why do astronomers track BX Andromedae?
Because its 14.6-hour period is short enough to observe multiple cycles in a single session, it serves as a convenient target for verifying eclipse timing and refining orbital parameters. Its Beta Lyrae geometry also makes it a useful case for studying how two stars of different sizes and temperatures interact gravitationally.
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