What specific stellar characteristic, measured by Henrietta Swan Leavitt, allowed Hubble to determine the intrinsic brightness of Cepheids?
Answer
The Period-Luminosity Relationship
The foundational insight that made extragalactic distance measurement possible was the Period-Luminosity Relationship, established by Henrietta Swan Leavitt. This cosmic law dictates a direct correlation between how long it takes a Cepheid variable star to cycle through its brightening and dimming phases (its period) and how luminous the star intrinsically is (its absolute magnitude). By accurately measuring the pulsation period of a Cepheid like V1 in Andromeda, Hubble could use Leavitt's established relationship to find out how bright the star truly was, regardless of its distance.
Related Questions
What instrument did Edwin Hubble utilize at Mount Wilson Observatory to resolve stars in the Andromeda Nebula?What specific stellar characteristic, measured by Henrietta Swan Leavitt, allowed Hubble to determine the intrinsic brightness of Cepheids?Why was simple trigonometric parallax inadequate for measuring the distance to the Andromeda Nebula (M31)?What was the designation given to the specific Cepheid variable star Hubble identified within the Andromeda Nebula in 1923?What were the two critical brightness measurements Hubble compared to solve the final distance to V1 using the inverse square law?According to Hubble's initial calculation, approximately how far away was the Andromeda Nebula from the Milky Way?What concept did the discovery of V1 confirm about the Andromeda Nebula (M31) relative to the Milky Way?Which astronomical entity was believed to encompass nearly the entirety of the known universe before Hubble's work resolved the spiral nebulae debate?What type of Cepheid stars were later found to be responsible for the initial underestimation of Andromeda's distance?What term describes standard celestial objects like Cepheids, whose intrinsic brightness is tied to a measurable timing property, used for gauging vast cosmic distances?