This Hubble Space Telescope image shows one of the galaxies in the survey to refine the measurement for how fast the universe expands with time, called the Hubble constant.
The galaxy, UGC 9391, contains two types of stars that astronomers use to calculate accurate distances to galaxies, a key measurement in determining the Hubble constant. The red circles mark the locations of Cepheid variable stars. These stars pulsate at rates that correspond to their true brightness, which can be compared with their apparent brightness as seen from Earth to accurately determine their distance.
The blue "X" at bottom right denotes the location of supernova 2003du, a special class of exploding star called a Type Ia supernova. These supernovae are another commonly used cosmic yardstick. They flare with the same brightness and are brilliant enough to be seen from relatively longer distances. Astronomers calibrate the supernovae with the Cepheids in galaxies such as UGC 9391 so that they can accurately calculate the distances to faraway exploding stars. UGC 9391 resides 130 million light-years from Earth.
The observations for this composite image were taken between 2012 and 2013 by Hubble's Wide Field Camera 3.
Credits
NASA, ESA, and A. Riess (STScI/JHU)| About The Object | |
|---|---|
| Object Name | UGC 9391 |
| Object Description | Barred spiral galaxy |
| R.A. Position | 14h 34m 37.02s |
| Dec. Position | 59° 20' 16.11" |
| Constellation | Draco |
| Distance | 130 million light-years (40 million parsecs) |
| About The Data | |
| Data Description | Data were provided by the HST proposal : A. Riess (JHU/STScI), L. Macri (Texas A&M University), A. Filippenko (University of California, Berkeley), S. Jha (Rutgers), S. Casertano (STScI), P. Nugent (Lawrence Berkeley National Laboratory), and M. Ganeshalingam (University of California, Berkeley). The science team comprises: A. Riess (JHU/STScI), L. Macri and S. Hoffmann (Texas A&M University), D. Scolnic (JHU/University of Chicago), S. Casertano (STScI), A. Filippenko (University of California, Berkeley), B. Tucker (University of California, Berkeley/Mount Stromlo Observatory), M. Reid (Harvard-Smithsonian Center for Astrophysics), D. Jones (JHU), J. Silverman (University of Texas, Austin), R. Chornock (Ohio University, Athens), P. Challis (Harvard-Smithsonian Center for Astrophysics), W. Yuan (Texas A&M University), and R. Foley (University of Illinois, Urbana-Champaign). |
| Instrument | HST>WFC3/UVIS |
| Exposure Dates | December 2012 - March 2013 |
| Filters | F350LP, F555W (V), and F814W (I) |
| About The Image | |
| Color Info | This image is a composite of separate exposures acquired by the WFC3/UVIS instrument. Several filters were used to sample various wavelengths. 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: F555W (V), Green: F350LP Red: F814W (I) |
| 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. |
