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.
Credits
Science
NASA, ESA, STScI, Zili Shen (Yale), Pieter van Dokkum (Yale), Shany Danieli (IAS)
Image Processing
Alyssa Pagan (STScI)
| About The Object | |
|---|---|
| Object Name | NGC 1052-DF2 |
| Object Description | Ultra Diffuse Galaxy |
| R.A. Position | 02:41:46.728 |
| Dec. Position | -08:24:09.871 |
| Constellation | Cetus |
| Distance | The galaxy is 72 million light-years away from Earth. |
| Dimensions | Image is 2.3 arcmin across (about 48,000 light-years) |
| About The Data | |
| Data Description | The HST observations include those from program (P. van Dokkum) |
| Instrument | ACS/WFC |
| Exposure Dates | 22 June 2020 - 16 Sept. 2020 |
| Filters | F606W, F814W |
| About The Image | |
| Color Info | 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 |
| Compass Image |  |
| 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. |
| Dimensions | The physical size of the object or the apparent angle it subtends on the sky. |
| About The Data | |
| Data Description |
|
| 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 | |
| Image Credit | The primary individuals and institutions responsible for the content. |
| Publication Date | The date and time the release content became public. |
| Color Info | A brief description of the methods used to convert telescope data into the color image being presented. |
| Orientation | The rotation of the image on the sky with respect to the north pole of the celestial sphere. |
