917 Lyka: An Overview
917 Lyka is a notable background asteroid situated in the inner region of the asteroid belt. With an estimated diameter of approximately 32 kilometers (20 miles), this celestial body was discovered on September 5, 1915, by the Russian astronomer Grigory Neujmin at the Simeiz Observatory located on the Crimean peninsula. The asteroid is classified as an X-type, characterized by its unique surface composition and properties. Named after Lyka, who was a friend of Neujmin’s sister, 917 Lyka serves as an intriguing example of the diverse population of asteroids that inhabit our solar system.
Orbit and Classification
Lyka is categorized as a non-family asteroid within the main belt’s background population. This classification is determined using the hierarchical clustering method that analyzes its proper orbital elements. The asteroid follows an elliptical orbit around the Sun, ranging from a distance of 1.9 to 2.9 astronomical units (AU) and completing one full orbit approximately every 3 years and 8 months, equating to about 1,342 days. It has a semi-major axis measuring 2.38 AU, an eccentricity of 0.20, and an inclination of about 5 degrees relative to the ecliptic plane.
The observational history of Lyka began at the Simeiz Observatory on September 1, 1926, which occurred eleven years after its initial discovery. This extended observation arc contributes significantly to our understanding of its orbital dynamics and characteristics.
Naming Conventions
The naming of minor planets often reflects personal connections or significant influences in the discoverer’s life. In this case, Grigory Neujmin chose to name the asteroid after Lyka, a friend of his sister. This choice was noted by Lutz Schmadel, who compiled information regarding minor planet names in his Dictionary of Minor Planet Names. Through private communications with Nikolai Chernykh, a long-time astronomer associated with the Simeiz Observatory, Schmadel learned about the significance behind Lyka’s name.
Physical Characteristics
917 Lyka is classified as an X-type asteroid in both the Tholen and SMASS taxonomies utilized by the Small Solar System Objects Spectroscopic Survey (S3OS2). X-type asteroids are typically characterized by their dark surfaces and metallic compositions, distinguishing them from other classifications based on spectral data.
Rotation Period
The rotational dynamics of Lyka have been studied extensively through photometric observations. A significant study conducted in January 2005 by Matthieu Conjat revealed a rotation period of approximately 7.867 hours with minimal brightness variation of about 0.17 magnitudes. This low amplitude suggests that Lyka has a relatively spherical shape, indicating uniformity in its physical structure.
Further observations conducted in October 2018 by Laurent Bernasconi and Alfonso Carreño confirmed this rotation period with slight variations in their measurements. Bernasconi recorded a period of 7.8838 hours while Carreño reported 7.889 hours, solidifying our understanding of this asteroid’s rotational characteristics.
Size and Albedo
The size and surface reflectivity (albedo) of 917 Lyka have been assessed through several astronomical surveys, including those conducted by IRAS (Infrared Astronomical Satellite), Akari (a Japanese satellite), and NASA’s NEOWISE mission. Measurements from these surveys indicate varying diameters for Lyka—ranging from approximately 28 kilometers to nearly 35 kilometers—alongside a spectrum of albedo values that suggest varying degrees of surface reflectivity.
The Collaborative Asteroid Lightcurve Link has derived a diameter estimate of about 27.89 kilometers based on its absolute magnitude of 11.6, providing valuable insight into its size relative to other asteroids within the belt. Additional measurements from WISE have presented mean diameters between 21.60 kilometers and upwards of 37 kilometers with corresponding albedos that span from low values around 0.026 to higher estimates approaching 0.05.
Occultation Observations
An interesting way to measure an asteroid’s dimensions is through occultation events—when an asteroid passes in front of a distant star, temporarily blocking its light. An occultation event involving Lyka was observed on March 4, 2005, which produced an elliptical dimension measurement of approximately 28 kilometers across both axes; however, it is important to note that this measurement was rated poorly concerning quality and reliability.
Conclusion
917 Lyka represents a fascinating study subject within the broader context of asteroids in our solar system. Discovered over a century ago by Grigory Neujmin, this X-type asteroid provides insights into both its physical characteristics and its orbital dynamics within the inner main belt region. The combination of observational data regarding its rotation period, size estimates from multiple sources, and unique naming backstory makes Lyka not only scientifically significant but also culturally rich in terms of its place within astronomical heritage.
As we continue to advance our technological capabilities for observing celestial bodies, further studies may yield even deeper insights into this intriguing asteroid’s properties and behavior over time, enhancing our understanding of similar objects throughout space.
Artykuł sporządzony na podstawie: Wikipedia (EN).