NGC 4414 A Majestic Spiral Galaxy
In 1995, the majestic spiral galaxy NGC 4414 was imaged by
the Hubble Space Telescope as part of the HST Key Project on
the Extragalactic Distance Scale over the course of two
months. Images were obtained with Hubble's Wide Field
Planetary Camera 2 (WFPC2) through three different color
filters. Based on their discovery and careful brightness
measurements of variable stars in NGC 4414, the Key Project
astronomers were able to make an accurate determination of the
distance to the galaxy.
The resulting distance to NGC 4414, 19.1 megaparsecs or
about 60 million light-years, along with similarly determined
distances to other nearby galaxies, contributes to
astronomers' overall knowledge of the rate of expansion of the
universe. The Hubble constant (H0) is the ratio of how fast
galaxies are moving away from us to their distance from us.
This astronomical value is used to determine distances, sizes,
and the intrinsic luminosities for many objects in our
universe, and the age of the universe itself.
Due to the large size of the galaxy compared to the WFPC2
detectors, only half of the galaxy observed was visible in the
datasets collected by the Key Project astronomers in 1995. In
1999, the Hubble Heritage Team revisited NGC 4414 and
completed its portrait by observing the other half with the
same filters as were used in 1995. The end result is a
stunning full-color look at the entire dusty spiral galaxy.
The new Hubble picture shows that the central regions of this
galaxy, as is typical of most spirals, contain primarily
older, yellow and red stars. The outer spiral arms are
considerably bluer due to ongoing formation of young, blue
stars, the brightest of which can be seen individually at the
high resolution provided by the Hubble camera. The arms are
also very rich in clouds of interstellar dust, seen as dark
patches and streaks silhouetted against the starlight.
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