Cepheid Variable Star V1 in Andromeda Galaxy
About This Image
Caption
In commemoration of Edwin Hubble's discovery of a Cepheid variable class star, called V1, in the neighboring Andromeda galaxy 100 years ago, astronomers partnered with the American Association of Variable Star Observers (AAVSO) to study the star. AAVSO observers followed V1 for six months, producing a plot, or light curve, of the rhythmic rise and fall of the star's light. Based on this data, the Hubble Space Telescope was scheduled to capture the star at its dimmest and brightest light. Edwin Hubble’s observations of V1 became the critical first step in uncovering a larger, grander universe than some astronomers imagined at the time. Once dismissed as a nearby "spiral nebula" measurements of Andromeda with its embedded Cepheid star served as a stellar milepost marker. It definitively showed that Andromeda was far outside of our Milky Way. Edwin Hubble went on to measure the distances to many galaxies beyond the Milky Way by finding Cepheid variables within those levels. The velocities of those galaxies, in turn, allowed him to determine that the universe is expanding.
About The Object
- Object Name
- M31-V1, M31
- Object Description
- Spiral galaxy and Cepheid Variable Star (inset)
- R.A. Position
- 00h 41m 26.99s
- Dec. Position
- 41° 10' 6.0"
- Constellation
- Andromeda
- Distance
- About 2.5 million light-years (0.8 megaparsecs)
About The Data
- Data Description
- The image (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).
- Instrument
- HST>WFC3/UVIS (inset)
- Exposure Dates
- December 2010 - January 2011, Exposure Time: 1.7 hours
- Filters
- F475X (Wide Blue) and F600LP (Long Pass)
About The Image
- Color Info
- These images (inset) are 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)
- Compass and Scale Image
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About The Object
- Object Name
- A name or catalog number that astronomers use to identify an astronomical object.
- Object Description
- The type of astronomical object.
- R.A. Position
- Right ascension – analogous to longitude – is one component of an object's position.
- Dec. Position
- Declination – analogous to latitude – is one component of an object's position.
- Constellation
- One of 88 recognized regions of the celestial sphere in which the object appears.
- Distance
- The 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 The Data
- Data Description
- Proposal: 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.
- Instrument
- The science instrument used to produce the data.
- Exposure Dates
- The date(s) that the telescope made its observations and the total exposure time.
- Filters
- The camera filters that were used in the science observations.
About The Image
- Color Info
- A brief description of the methods used to convert telescope data into the color image being presented.
- Compass and Scale Image
- An astronomical image with a scale that shows how large an object is on the sky, a compass that shows how the object is oriented on the sky, and the filters with which the image was made.
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