NGC4414

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. An international team of astronomers, led by Dr. Wendy
Freedman of the Observatories of the Carnegie Institution of
Washington, observed this galaxy on 13 different occasions 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.

Image Credit: Hubble Heritage Team (AURA/ STScI/ NASA)