Tracing spiral arms in infrared

Featured in this NASA/ESA/CSA James Webb Space Telescope Picture of the Month is the spiral galaxy NGC 2090, located in the constellation Columba. This combination of data from Webb’s MIRI and NIRCam instruments shows the galaxy’s two winding spiral arms and the swirling gas and dust of its disc in magnificent and unique detail.

This was one of the group of galaxies studied early on by the NASA/ESA Hubble Space Telescope, observing Cepheid variable stars in it as part of refining the measurement of the Hubble constant. The Cepheid-based measurement from that study in 1998 put NGC 2090 as 37 million light-years away; the newest measurements have NGC 2090 slightly farther away, at 40 million light-years. Hubble is to this day surveying galaxies in visible and ultraviolet light; alongside this Webb image a new Hubble image of NGC 2090 has also been published this week, which you can find here.

Before and since that project, NGC 2090 has been well studied as a very prominent nearby example of star formation. It has been described as a flocculent spiral, meaning a spiral galaxy with a patchy, dusty disc and arms that are flaky or not visible at all. Visible-light images show this well, but the near-infrared data from NIRCam used in this image reveal the spiral arms with remarkable clarity. NIRCam also picks up bright light from stars, displayed by the blue colours most visible in the centre. Meanwhile, mid-infrared light emitted mainly by the important carbon-based compounds known as polycyclic aromatic hydrocarbons along the many strands of gas and dust is captured by MIRI and shown here in red.

These data on NGC 2090 were collected as part of an observing programme (#3707) taking a census of nearby massive, star-forming galaxies much like it. These galaxies are at just the right distance, with the right size and level of activity, that Webb’s instruments can capture a comprehensive picture of the star-forming activity, including the tightly-bound clusters that stars often form in, and the clouds of gas in the galaxy in which stars can be born. The rich collection of detailed images like this one will be of value to astronomers studying this area for years to come.

[Image Description: A spiral galaxy with a wide, oval-shaped disc. It has a shining spot at the centre from which two curving, pale red spiral arms emerge, wrapping once each around the galaxy. They’re surrounded by a whirl of bright threads and patches of dust, with spots of star formation scattered throughout. The glow of the disc fades smoothly into the background where some patches of dust can be seen, as well as foreground stars.]

Links

• Slider Tool: Webb and Hubble's views of NGC 2090
• Video: Pan of NGC 2090
• Video: Hubble and Webb's views of NGC2090
• Image on ESA website