Cepheid Variable Star P42 in NGC 5468

 Cepheid Variable Star P42 in NGC 5468

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.



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
  • Proposal: 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.
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.