CH Cyg: A Close-up View of Codependent Stellar Living

June 9, 2010
Credits: Inset image: X-ray: NASA/CXC/SAO/M.Karovska et al; Optical: NASA/ STScI; Radio: NRAO/VLA Wide field: DSS

( -- This image shows the symbiotic system known as CH Cyg, located only about 800 light years from Earth. The large image shows an optical view of CH Cyg, using the Digitized Sky Survey, and the inset shows a composite image containing Chandra X-ray data in red, optical data from the Hubble Space Telescope (HST) in green, and radio data from the Very Large Array (VLA) in blue.

CH Cyg is a containing a white dwarf that feeds from the wind of a red . The material from the wind forms a hot accretion disk around the white dwarf before crashing onto the star. CH Cyg is one of only a few hundred symbiotic systems known, and one of the closest to the Earth. Symbiotic systems are fascinating objects, where the components are codependent and influence each other's structure, daily life, and evolution. They are likely progenitors of bipolar planetary nebulas and they could make up some of the systems that later explode as Type Ia supernovas, spectacular explosions visible across cosmological distances.

The image in the inset shows a recent powerful jet in CH Cyg, caught in action by Chandra, HST and VLA. The material in the jet is moving with a speed of over three million miles per hour and is powered by material spinning in the accretion disk around the white dwarf. The detailed structure of the X-ray jet is seen for the first time in this system, showcasing the superb high-resolution capabilities of Chandra. The curved appearance of the jet, shown in the optical by the green arc in the lower right part of the inset, reveals evidence that the direction of the jet rotates. This precession may be caused by wobbling of the accretion disk, in a manner similar to a spinning top.

Clumps in the outer jet, seen in X-rays, optical and radio data, provide evidence for powerful mass ejections by the jet in the past, and for interactions with shells of gas formed by the red giant. The jet can be seen as close as 20 astronomical units (AU) from the binary system, where one AU corresponds to the average distance from the Earth to the Sun. The jet extends out to distances as large as 750 AU from the binary, which is about 20 times the distance between the Sun and Pluto.

The shape of the jet in CH Cyg shows striking parallels with jets seen in very different astrophysical contexts, such as young stars or supermassive black holes located at the centers of galaxies. Because of its proximity it may be used as a "toy model" to study jet formation and propagation in much more complex and distant systems.

In a biological setting, "symbiosis" was originally defined as the "living together of unlike organisms," and describes close and long- term interactions between different species. In this sense, the astrophysical usage is apt because and are very different stars. A red giant is extremely large and bright, with a relatively low temperature, while a white dwarf is small and faint with a high temperature.

Symbiosis is usually beneficial or essential to the survival of at least one of the species in the system, for example bees and flowers, birds and rhinos and clownfish and anemones. In the astrophysical context of symbiotic systems, the survival of the hot disk around the white dwarf, where the jet originates, depends on the wind of the red giant. The power, mass and the speed of the jet is closely related to the white dwarf environment including the disk. Once formed, the jet disrupts and shapes the extended envelope and environment of the red giant, as the latter evolves toward the end point of its life as a . However, in some cases, if the white dwarf gains too much mass from the red giant, it may end up being completely destroyed in a spectacular Type Ia supernova explosion.

A paper describing the new observations of CH Cyg was published in the February 20, 2010 issue of the Astrophysical Journal Letters and was led by Margarita Karovska from the Harvard-Smithsonian Center for Astrophysics (CfA). The co-authors are Terrance Gaetz from CfA, Christopher Carilli from the National Radio Astronomy Observatory, Warren Hack from Space Telescope Science Institue, and John Raymond and Nicholas Lee, both from CfA.

Explore further: Stars Flood Space with Gravitational Waves

Related Stories

Stars Flood Space with Gravitational Waves

May 30, 2005

A scientist using NASA's Chandra X-ray Observatory has found evidence that two white dwarf stars are orbiting each other in a death grip, destined to merge. The data indicate gravitational waves are carrying energy away from ...

A sub-stellar Jonah: Brown dwarf survives being swallowed

August 2, 2006

Using ESO's Very Large Telescope, astronomers have discovered a rather unusual system, in which two planet-size stars, of different colours, orbit each other. One is a rather hot white dwarf, weighing a little bit less than ...

White dwarf and ultra-cool dwarf keep their distance

April 18, 2007

Scientists from the University of Hertfordshire have discovered a rare binary system consisting of a white dwarf, a Sun-like star that has reached the end of its life, and an ultra-cool dwarf, which is the smallest kind of ...

Supernova remnant is an unusual suspect

June 9, 2009

A new image from NASA's Chandra X-ray Observatory shows a supernova remnant with a different look. This object, known as SNR 0104-72.3 (SNR 0104 for short), is in the Small Magellanic Cloud, a small neighboring galaxy to ...

Symbiotic Stars

February 22, 2010

( -- Many, perhaps even most stars, are members of binaries -- two stars that orbit each other. Symbiotic stars are a small subset of binaries with an attitude: they display characteristic, dramatic, episodic ...

Recommended for you

NASA's space-station resupply missions to relaunch

November 29, 2015

NASA's commercial space program returns to flight this week as one of its private cargo haulers, Orbital ATK, is to launch its first supply shipment to the International Space Station in more than 13 months.

The hottest white dwarf in the Galaxy

November 25, 2015

Astronomers at the Universities of Tübingen and Potsdam have identified the hottest white dwarf ever discovered in our Galaxy. With a temperature of 250,000 degrees Celsius, this dying star at the outskirts of the Milky ...

1 comment

Adjust slider to filter visible comments by rank

Display comments: newest first

2 / 5 (2) Jun 10, 2010
Intriguing! Especially the finding that "The shape of the jet in CH Cyg shows striking parallels with jets seen in very different astrophysical contexts, such as young stars or supermassive black holes located at the centers of galaxies."

What could that possibly mean?

With kind regards,
Oliver K. Manuel

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.