Skip to main content

Globular Cluster NGC 6397 Brightness "Gap" Feature

Read News Release View All Press Releases

Graph. Top left corner, on black background, label on first line in yellow reads Globular Cluster NGC 6397. In larger, white font, label on second line reads Red Dwarf Brightness “Gap” Feature. On x axis, across bottom of graph, is label Apparent Brightness (Magnitude). Horizontally above label are 8 regularly spaced tick marks at intervals from 20.2 to 21.6. On y axis, running up left side of graph, is label Number of Stars. From bottom to top are 10 regularly spaced tick marks from 0 to 450. Within graph, key shows two features: dashed yellow line indicates empirical model, and blue rectangle indicates observations. Blue, blocky, irregular, saw-tooth features show number of stars at given apparent brightness. Trend gradually rises until it steeply drops between 21.0 and 21.2. This is labeled Brightness Gap. Following gap, trend briefly rises again until it slopes down toward end of graph. Dashed yellow line marking model closely corresponds to rising and falling of observed data.

About This Image

Release Date

June 03, 2026 10:00AM (EDT)

Read the Release

Release ID: 2026-405

Permissions

Content Use Policy

Download Options

Caption

This graph shows the brightness gap that scientists found using Euclid when they grouped the globular cluster NGC 6397’s stars by brightness and color. What they observed was a thin “gap” of expected but missing low-mass stars called red dwarfs. The observations fit well with their model prediction. This gap is thought to be linked to changes occurring within some stars’ interiors, giving astronomers a glimpse at processes happening inside stars even from thousands of light-years away. This is the first time the gap feature was discovered in a globular cluster. 

Credits

Illustration

Massimo Griggio (STScI), Leah Hustak (STScI)

Keywords

Share This Page

This site is protected by reCAPTCHA and the Google

Contact our News Team 

Contact our Outreach Office