At the center of these side-by-side images is a special class of star used as a milepost marker for measuring the universe’s rate of expansion – a Cepheid variable star. The two images are very pixelated because they are a very zoomed-in view of a distant galaxy. Each of the pixels represents one or more stars. The image from the James Webb Space Telescope is significantly sharper at near-infrared wavelengths than Hubble (which is primarily a visible-ultraviolet light telescope). By reducing the clutter with Webb’s crisper vision, the Cepheid stands out more clearly, eliminating any potential confusion. Webb was used to look at a sample of Cepheids and confirmed the accuracy of the previous Hubble observations that are fundamental to precisely measuring the universe’s expansion rate and age.
Credits
Image
NASA, ESA, CSA, STScI, Adam G. Riess (JHU, STScI)
| About The Object | |
|---|---|
| Object Name | Cephied P42 |
| Object Description | Cephied in NGC 5468 |
| R.A. Position | 14:06:35.01 |
| Dec. Position | -05:27:15.72 |
| Constellation | Virgo |
| Distance | About 130 million light-years |
| About The Data | |
| Data Description | This image was created with Webb and Hubble data from proposals: 1685 and 11570 (A. Riess). Image processing: Alyssa Pagan (STScI). |
| Instrument | Hubble>WFC3/IR Webb>NIRCam |
| Exposure Dates | Hubble> 28 December 2017- 25 March 2018 Webb> 28 June 2023, 15 July 2023 |
| Filters | Hubble> F160W Webb> F150W |
| About The Image | |
| Color Info | The images are separate exposures acquired by the NIRCam instrument on the James Webb Space Telescope (left) and the WFC3/IR instrument on the Hubble Space Telescope (right). |
| 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. |
