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NGC1052-DF2
Hubble Captures a Ghostly Galaxy
This Hubble Space Telescope snapshot reveals an unusual "see-through" galaxy. The giant cosmic cotton ball is so diffuse and its ancient stars so spread out that distant galaxies in the background can be seen through it.
Called an ultra-diffuse galaxy, this galactic oddball is almost as wide as the Milky Way, but it contains only 1/200th the number of stars as our galaxy. The ghostly galaxy doesn't appear to have a noticeable central region, spiral arms, or a disk.
Researchers calculated a more accurate distance to the galaxy, named NGC 1052-DF2, or DF2, by using Hubble to observe about 5,400 aging red giant stars. Red giant stars all reach the same peak brightness, so they are reliable yardsticks to measure distances to galaxies.
The research team estimates that DF2 is 72 million light-years from Earth. They say the distance measurement solidifies their claim that DF2 lacks dark matter, the invisible glue that makes up the bulk of the universe's contents. The galaxy contains at most 1/400th the amount of dark matter that the astronomers had expected.
The observations were taken between December 2020 and March 2021 with Hubble's Advanced Camera for Surveys.
About the Object
- R.A. PositionR.A. PositionRight ascension – analogous to longitude – is one component of an object's position.02:41:46.728
- Dec. PositionDec. PositionDeclination – analogous to latitude – is one component of an object's position.-08:24:09.871
- ConstellationConstellationOne of 88 recognized regions of the celestial sphere in which the object appears.Cetus
- 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.The galaxy is 72 million light-years away from Earth.
- DimensionsDimensionsThe physical size of the object or the apparent angle it subtends on the sky.Image is 2.3 arcmin across (about 48,000 light-years)
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 HST observations include those from program 15851 (P. van Dokkum)
- InstrumentInstrumentThe science instrument used to produce the data.ACS/WFC
- Exposure DatesExposure DatesThe date(s) that the telescope made its observations and the total exposure time.22 June 2020 - 16 Sept. 2020
- FiltersFiltersThe camera filters that were used in the science observations.F606W, F814W
- Object NameObject NameA name or catalog number that astronomers use to identify an astronomical object.NGC 1052-DF2
- Object DescriptionObject DescriptionThe type of astronomical object.Ultra Diffuse Galaxy
- Release DateJune 17, 2021
- Science ReleaseMystery of Galaxy’s Missing Dark Matter Deepens
- CreditNASA, ESA, STScI, Zili Shen (Yale), Pieter van Dokkum (Yale), Shany Danieli (IAS); Image Processing: Alyssa Pagan (STScI)
These images are a composite of separate exposures acquired by the ACS/WFC instrument on the Hubble Space Telescope. Several filters were used to sample narrow 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: Blue: F606W Green: F606W + F814W Red: F814W
Related Images & Videos
NGC1052-DF2 with Pull-out of Red Giant Stars
Astronomers Use Red Giant Stars to Calculate Distance to Mysterious Galaxy This Hubble Space Telescope image offers a sampling of aging, red stars in the ultra-diffuse galaxy NGC 1052-DF2, or DF2. The galaxy continues to puzzle astronomers because it is lacking dark matter, an...
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Claire Andreoli
NASA’s Goddard Space Flight Center
Greenbelt, Maryland
claire.andreoli@nasa.gov
