Astronomers have trained the James Webb Space Telescope (JWST) on a galaxy named “Firefly Sparkle.” But the young galaxy may not invite you to its birthday party as it is already accompanied by galaxies newly named “Firefly-Best Friend” and “Firefly-New Best Friend!”
Firefly Sparkle does give astronomers a gift: the first glimpse of a typical galaxy in its early stages in the context of a very young universe.
Indeed, the galaxy’s high redshift allowed scientists to date the light we see back to when the universe was just 600 million years old (it is now 13.8 billion years old).
Redshift is the phenomenon which occurs when the source of light moves away from an observer, stretching the light’s wavelength toward the red part of the spectrum. Redshift is due to the expansion of space itself and objects with greater redshifts are older.
Firefly Sparkle was first observed with the Hubble Space Telescope during a survey of the galaxy cluster MACS J1423.8 + 2404. This cluster is massive and as a result, it magnifies the light coming from objects directly behind it but in Earth’s line of sight.
This gravitational lensing effect combined with the sensitivity of the JWST allowed astronomers to study Firefly Sparkle in detail.
The images had enough resolution to show that most of the young galaxy’s mass is concentrated in just 10 star clusters. This makes Firefly Sparkle the farthest galaxy with well-resolved star clusters imaged with spectrographic instruments.
The team also discovered that the galaxy is gas-rich and has a total mass approximately 10 million times the mass of the Sun, which makes it similar in size to that of a progenitor Milky Way.
The authors suggest that observation of Firefly Sparkle could help us understand how the early Milky Way formed. Perhaps cosmic friendship bracelets are in order.
The research is published in the journal Nature.
