HD 51418
An extreme lanthanide Ap star with a magnetic companion.
HD 51418, also known as NY Aurigae, is a chemically peculiar Ap star and an α² Canum Venaticorum variable in the northern constellation Auriga, roughly 178 parsecs from Earth. Its apparent magnitude hovers around 6.6, and with a spectral type of A0, it may appear as a faint whitish point of light to the naked eye under excellent conditions. The star is classified as an "extreme lanthanide star," meaning its spectrum shows strong emission lines from an overabundance of metals like europium, dysprosium, and holmium.
The star's variability was announced in 1972 by Austin F. Gulliver and colleagues, and it received its variable star designation, NY Aurigae, in 1975. HD 51418 has a strong magnetic field that fluctuates between -22 and 75 milliteslas. The magnetic minimum coincides with the star's minimum brightness and the weakest detection of rare-earth elements.
In 2009, speckle imaging revealed a previously unseen companion star at a separation of 0.15 arcseconds. This secondary star, listed as component B in the double star system WDS 06593+4219, is an F-type star with an apparent magnitude of 10.0.
- Distance
- 178 pc
- Apparent magnitude
- ~6.6 (variable)
- Spectral type
- A0
- Variable star designation
- NY Aurigae
- Magnetic field strength range
- -22 to 75 mT
- Companion apparent magnitude
- 10.0
- Companion spectral type
- F
Lore & Background
In 1972, Austin F. Gulliver et al. announced that HD 51418 is a variable star, and it received its variable star designation, NY Aurigae, in 1975. The star possesses a strong magnetic field that fluctuates in strength between -22 and 75 mT. The magnetic minimum occurs concurrently with the minimums in luminosity and rare-earth detection. Speckle imaging observations conducted in 2009 revealed a previously unresolved companion star at a separation of 0.15 arcseconds. This secondary star, component 'B' of the double star WDS 06593+4219 as designated in the Washington Double Star Catalog, is an F-type star with an apparent magnitude of 10.0.
Reader's Guide
HD 51418 (NY Aurigae) holds significance as an extreme lanthanide star, a rare subclass of chemically peculiar Ap stars that show pronounced overabundances of rare-earth elements such as europium, dysprosium, and holmium. Its variability, magnetic field, and chemical peculiarities are closely linked: the magnetic minimum coincides with minima in both luminosity and rare-earth detection, offering insight into the rotational modulation of surface spots and the distribution of elements in stellar atmospheres. The discovery of a visual companion in 2009 via speckle imaging adds a binary context, though the physical association and orbital parameters remain uncharacterized. As an α² Canum Venaticorum variable, it contributes to the understanding of magnetic chemically peculiar stars and their pulsation or rotation-driven variability. Its legacy lies in exemplifying the extreme end of lanthanide enrichment, alongside stars like Przybylski's Star and GY Andromedae, and in providing a benchmark for studies of magnetic fields and element stratification in A-type stars.
Did You Know?
- HD 51418 is an 'extreme lanthanide star' with overabundances of europium, dysprosium, and holmium.
- Its magnetic field fluctuates between -22 and 75 mT, with minima coinciding with luminosity and rare-earth detection minima.
- A visual companion of spectral type F and magnitude 10.0 was discovered in 2009 at a separation of 0.15 arcseconds.
- The star was announced as variable in 1972 by Austin F. Gulliver et al. and designated NY Aurigae in 1975.
Frequently Asked Questions
What is HD 51418?
HD 51418, also catalogued as NY Aurigae, is a chemically peculiar A0 star in the northern constellation Auriga. It is classified as an α² Canum Venaticorum variable, meaning its brightness waxes and wanes as rotationally modulated chemical abundance bands cross the visible disk.
How far is HD 51418 from Earth and can you see it?
The star lies roughly 178 parsecs (about 579 light-years) away and shines at an apparent magnitude near 6.6. Under exceptionally dark skies it may be glimpsed as a faint whitish point of light, though a small telescope makes it far easier to confirm.
What does it mean that HD 51418 is an "extreme lanthanide star"?
This designation highlights that its spectrum shows unusually strong emission lines from heavy rare-earth elements such as europium, dysprosium, and holmium. Those lanthanide abundances are far above what a normal A-type star would display, a defining trait of the Ap subclass.
What is the magnetic field strength of HD 51418?
Published measurements place its surface field in a range of roughly −22 to 75 millitesla, suggesting a non-uniform or evolving geometry. The system also includes a faint companion at apparent magnitude 10.0 that contributes to the overall magnetic environment.
Who first announced the variability of HD 51418?
Austin F. Gulliver and his colleagues reported the star's variable behaviour in 1972, and it has carried the designation NY Aurigae in variable-star catalogues ever since. No single dramatic "story arc" applies; its interest lies in the steady, long-term monitoring of its rotational modulation and peculiar chemistry.
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