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Snapshots of the Star that Changed the Universe
Views of a famous pulsating star taken nearly 90 years apart and a portrait of its galactic home are shown in this image collection.
The pancake-shaped disk of stars, gas, and dust that make up the Andromeda galaxy, or M31, is shown in the image at left. Andromeda is a Milky Way neighbor and resides 2 million light-years away.
The tiny white box just above center outlines the Hubble Space Telescope view. An arrow points to the Hubble image, taken by the Wide Field Camera 3. The snapshot is blanketed with stars, which look like grains of sand.
The white circle at lower left identifies Hubble variable number one, or V1, the Cepheid variable star discovered by astronomer Edwin Hubble in 1923. Cepheid variables are pulsating stars that brighten and fade in a predictable pattern. Astronomers use them to calculate how far away they are from Earth.
The large white box outlines the region imaged by astronomer Edwin Hubble, who used the 100-inch Hooker telescope, the most powerful telescope of that era. An arrow points to a copy of Hubble's image of Andromeda, which was made on a 4-inch-by-5-inch glass plate and dated Oct. 6, 1923.
Edwin Hubble originally identified three novae, a class of exploding star, by writing "N" next to each object. Later, Hubble realized that the nova at top right was actually a Cepheid variable. He crossed out the "N" and wrote "VAR," for variable. This star allowed Hubble to calculate a reliable distance to Andromeda, proving that it was a separate galaxy outside our Milky Way.
About the Object
- R.A. PositionR.A. PositionRight ascension – analogous to longitude – is one component of an object's position.00h 41m 26.99s
- Dec. PositionDec. PositionDeclination – analogous to latitude – is one component of an object's position.41° 10' 6.0"
- ConstellationConstellationOne of 88 recognized regions of the celestial sphere in which the object appears.Andromeda
- DistanceDistanceThe physical distance from Earth to the astronomical object. Distances within our solar system are usually measured in Astronomical Units (AU). Distances between stars are usually measured in light-years. Interstellar distances can also be measured in parsecs.About 2.5 million light-years (0.8 megaparsecs)
About the Data
- Data DescriptionData DescriptionProposal: A description of the observations, their scientific justification, and the links to the data available in the science archive.
Science Team: The astronomers who planned the observations and analyzed the data. "PI" refers to the Principal Investigator.The image (top inset) was created from Hubble data from proposal 12326: K. Noll (PI), Z. Levay, M. Mutchler, T. Borders, L. Frattare, M. Livio, C. Christian, D. Soderblom, and H. Bond (Hubble Heritage Team/STScI). Note:The Hubble Space Telescope observations of Hubble's Variable M31-V1 were made possible from ground-based data provided by the American Association of Variable Star Observers (AAVSO). - InstrumentInstrumentThe science instrument used to produce the data.HST>WFC3/UVIS (top inset)
- Exposure DatesExposure DatesThe date(s) that the telescope made its observations and the total exposure time.December 2010 - January 2011, Exposure Time: 1.7 hours
- FiltersFiltersThe camera filters that were used in the science observations.F475X (Wide Blue) and F600LP (Long Pass)
- Object NameObject NameA name or catalog number that astronomers use to identify an astronomical object.Andromeda Galaxy, M31
- Object DescriptionObject DescriptionThe type of astronomical object.Spiral galaxy
- Release DateMay 23, 2011
- Science ReleaseHubble Views the Star that Changed the Universe
- Credits
This image (top inset) is a composite of separate exposures acquired by the WFC3 instrument on HST. Several filters were used to sample broad wavelength ranges. The color results from assigning different hues (colors) to each monochromatic (grayscale) image associated with an individual filter. In this case, the assigned colors are: Cyan: F475X (Wide Blue) Orange: F600LP (Long Pass)
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Claire Andreoli
NASA’s Goddard Space Flight Center
Greenbelt, Maryland
claire.andreoli@nasa.gov
