Variable Stars: Eta Carinae

Tracing outbursts of tightly orbiting stars
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Eta Carinae Interactive

A ribbed, hourglass shape with a bright center
Lobed shape with pinched waist, with dots in the background
Hourglass shape with lines extending from center Hourglass shape with lines extending from center
Diffuse, cloud-like structure with a brighter dot at center
Hourglass shape with surrounding, extended material
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Warm, glowing dust that was ejected during the 1840s is now heated by radiation from the central stars.

Mirrored lobes of gas and dust surround Eta Carinae’s central stars, which are flanked at right by ragged, shock-heated gas.

When clumpy dust is struck by ultraviolet light from the hidden stars, it can send out rays of light or cast long, thin shadows.

X-rays at the center highlight the stars’ colliding winds, while beyond that expelled material crashes into earlier ejections.

Two massive stars, locked in a tight orbit, continue to shape gas and dust that were ejected over a hundred years ago.


A Story Of Variable Stars: Eta Carinae

Tracking the outbursts of two tightly orbiting stars.

The brightness of some stars varies over time due to a variety of factors, including their age and interactions with other nearby objects. The variation in the brightness of some stars tells us about how they evolve, and helps researchers learn about their properties inside and out.

In the 1840s, what looked like a single star erupted in the night sky. One of the two stars in Eta Carinae ejected some of its mass, brightening the pair and making them the second-brightest star visible in the night sky for more than a decade. These stars are extremely bright and prone to ongoing outbursts, which are causing the stars to lose mass. Observations made in multiple wavelengths of light have allowed researchers to determine the timing of each outburst, as well as the materials it sent out, which formed two lobes of gas and dust. Eta Carinae offers researchers an ongoing opportunity to study massive stars.

Quick Facts: Eta Carinae

Type of object: Extreme, high-mass star system

Distance from Earth: 7,500 light-years

Location in the sky: Carina Constellation in the Southern sky

Did you know: In the 1840s, Eta Carinae brightened, becoming the second-brightest star visible in the night sky for more than a decade, an event known as the Great Eruption. In the 1860s, it faded from view. Since the late 1990s, it has slowly brightened, recently becoming visible to the naked eye again.

Explore More About Variable Stars

Find out more with these additional resources from NASA’s Universe of Learning

Credits: Eta Carinae

Infrared image from the 6.5 meter Magellan telescopes at Las Campanas Observatory, Chile courtesy of Dr. Nathan Smith, University of Arizona

Visible light image from the Hubble Space Telescope: NASA, STScI

Ultraviolet light image from the Hubble Space Telescope: NASA, STScI

X-ray light image from the Chandra X-ray Observatory: NASA, CXC, GSFC, K. Hamaguchi, et al.

Multi-wavelength image (infrared, visible, ultraviolet, X-ray): NASA, ESA, N. Smith (University of Arizona), J. Morse (BoldlyGo Institute), and A. Pagan

Subject-matter expertise provided by Dr. Jon Morse, Dr. Nathan Smith

Produced by the Space Telescope Science Institute’s Office of Public Outreach