Exoplanet WASP-96 b (NIRISS Transit Light Curve)

 Exoplanet WASP-96 b (NIRISS Transit Light Curve)

A light curve from Webb’s Near-Infrared Imager and Slitless Spectrograph (NIRISS) shows the change in brightness of light from the WASP-96 star system over time as the planet transits the star. A transit occurs when an orbiting planet moves between the star and the telescope, blocking some of the light from the star. This observation was made using NIRISS’s Single-Object Slitless Spectroscopy (SOSS) mode, which involves capturing the spectrum of a single bright object, like the star WASP-96, in a field of view. 

To capture these data, Webb stared at the WASP-96 star system for 6 hours 23 minutes, beginning about 2½ hours before the transit and ending about 1½ hours after the transit was complete. The transit itself lasted for just under 2½ hours. The curve includes a total of 280 individual brightness measurements – one every 1.4 minutes.

Because the observation was made using a spectrograph, which spreads the light out into hundreds of individual wavelengths, each of the 280 points on the graph represents the combined brightness of thousands of wavelengths of infrared light.

The actual dimming caused by the planet is extremely small: The difference between the brightest and dimmest points is less than 1.5 percent. NIRISS is ideally suited for this observation because it has the ability to observe relatively bright targets over time, along with the sensitivity needed to measure such small differences in brightness: In this observation, the instrument was able to measure differences in brightness as small as 0.02 percent.

Although the presence, size, mass, and orbit of the planet had already been determined based on previous transit observations, this transit light curve can be used to confirm and refine existing measurements, such as the planet’s diameter, the timing of the transit, and the planet’s orbital properties. 

WASP-96 b is a hot gas giant exoplanet that orbits a Sun-like star roughly 1,150 light-years away, in the constellation Phoenix. The planet orbits extremely close to its star (less than 1/20th the distance between Earth and the Sun) and completes one orbit in less than 3½ Earth-days. The planet’s discovery, from ground-based observations, was announced in 2014. 

The background illustration of WASP-96 b and its Sun-like star is based on current understanding of the planet from both NIRISS spectroscopy and previous ground- and space-based observations. Webb has not captured a direct image of the planet or its atmosphere.

NIRISS was contributed by the Canadian Space Agency. The instrument was designed and built by Honeywell in collaboration with the Université de Montréal and the National Research Council Canada.

For a full array of Webb’s first images and spectra, including downloadable files, please visit: https://webbtelescope.org/news/first-images




About The Object
Object Name WASP-96 b
Object Description Hot Gas Giant Exoplanet
R.A. Position 00:04:11.18
Dec. Position -47:21:38.29
Constellation Phoenix
Distance 350 parsecs (1.150 light-years)
Dimensions 1.2 times the radius of Jupiter (13.5 times the radius of Earth) 0.48 times the mass of Jupiter (153 times mass of Earth)
About The Data
Data Description This image was created with Webb data from proposal . It is part of Webb Early Release Observations. The Early Release Observations and associated materials were developed, executed, and compiled by the ERO production team: Jaclyn Barrientes, Claire Blome, Hannah Braun, Matthew Brown, Margaret Carruthers, Dan Coe, Joseph DePasquale, Nestor Espinoza, Macarena Garcia Marin, Karl Gordon, Alaina Henry, Leah Hustak, Andi James, Ann Jenkins, Anton Koekemoer, Stephanie LaMassa, David Law, Alexandra Lockwood, Amaya Moro-Martin, Susan Mullally, Alyssa Pagan, Dani Player, Klaus Pontoppidan, Charles Proffitt, Christine Pulliam, Leah Ramsay, Swara Ravindranath, Neill Reid, Massimo Robberto, Elena Sabbi, Leonardo Ubeda.  The EROs were also made possible by the foundational efforts and support from the JWST instruments, STScI planning and scheduling, Data Management teams, and Office of Public Outreach.
Instrument Near-Infrared Imager and Slitless Spectrograph (NIRISS), time-series Single-Object Slitless Spectroscopy (SOSS) mode
Exposure Dates June 21, 2022 (6.4-hour observation)
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.