Astronomers Use Hubble to Tighten the Cosmic Distance Ladder
This is a ground-based telescope's view of the Large Magellanic Cloud, a satellite galaxy of our Milky Way. The inset image, taken by the Hubble Space Telescope, reveals one of many star clusters scattered throughout the dwarf galaxy.
The cluster members include a special class of pulsating star called a Cepheid variable, which brightens and dims at a predictable rate that corresponds to its intrinsic brightness. Once astronomers determine that value, they can measure the light from these stars to calculate an accurate distance to the galaxy. When the new Hubble observations are correlated with an independent distance measurement technique to the Large Magellanic Cloud (using straightforward trigonometry), the researchers were able to strengthen the foundation of the so-called "cosmic distance ladder." This "fine-tuning" has significantly improved the accuracy of the rate at which the universe is expanding, called the Hubble constant.
Credits
NASA, ESA, A. Riess (STScI/JHU), and Palomar Digitized Sky Survey| About The Object | |
|---|---|
| Object Name | Large Magellanic Cloud (DSS View) with Star Cluster Overlay (Hubble) |
| Object Description | Cepheid Variable Star in Satellite Galaxy |
| R.A. Position | 05:08:43.95 |
| Dec. Position | -68:45:27.97 |
| Constellation | Dorado |
| Distance | 163,000 light-years |
| Dimensions | Main image is about 6 degrees across (about 17,000 light-years); Inset image is 0.6 arcmin across (about 30 light-years) |
| About The Data | |
| Data Description | Data of cepheid variable stars in the LMC were obtained from the HST proposal (A. Riess) |
| Instrument | WFC3/UVIS |
| Exposure Dates | 14 Dec 2018 |
| Filters | F814W, F555W |
| About The Image | |
| Color Info | These images are composites of separate exposures acquired by the WFC3 instrument on the Hubble Space Telescope. 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: Blue: F555W (V) Green: F555W (V) and F814W (I) 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. |
