It's Always a Windy Day Around This Baby Star
Some young sun-like stars generate an odd infrared signal that is likely caused by interactions with neighboring stars, producing powerful stellar winds. Continue reading →
T Tauri stars are young stars not so dissimilar to what our sun would have looked like when it was an infant, approximately 4.5 billion years ago. These stellar objects are often easy to identify as they emit a very specific type of radiation, but some T Tauris buck the trend and generate a very strange signature of infrared light.
Now, astronomers using the powerful Atacama Large Millimeter/submillimeter Array (ALMA) in the Atacama Desert, Chile, think they've worked out why some of these T Tauris are oddballs - they have some pretty wild space weather.
"The material in the disk of a T Tauri star usually, but not always, emits infrared radiation with a predictable energy distribution," said astronomer Colette Salyk, of the National Optical Astronomical Observatory (NOAO) in Tucson, Ariz. "Some T Tauri stars, however, like to act up by emitting infrared radiation in unexpected ways."
Like our young sun, T Tauris are enshrouded in a dusty protoplanetary disk and are not visible in optical light. ALMA can cut through the dust and analyze the properties of the radiation they produce.
While studying AS 205 N, a T Tauri star located 407 light-years from Earth in a star-forming region in the constellation Ophiuchus, Salyk's team discovered what may be causing the anomalous infrared signal that some T Tauri's generate. ALMA was used to track the distribution of carbon monoxide gas, which is easily identifiable by ALMA and can be used as a tracer for the gas and dust blowing from the star in a stellar wind.
After careful analysis, the astronomers found that AS 205 N's strange signal is probably being caused by its binary star partner, AS 205 S, which is itself a binary star. This multi-star configuration appears to be pulling material from AS 205 N, producing a powerful stellar wind where material is being dragged from its surface rather than being blown away by the young star.
"We are hoping these new ALMA observations help us better understand winds, but they have also left us with a new mystery," said Salyk. "Are we seeing winds, or interactions with the companion star?"
This research has important implications for how star systems form protoplanetary disks and eventually evolve to form a system of planets, like the mature solar system.
This research has been published in the Astrophysical Journal.
Artist impression of the T Tauri star AS 205 N and its companion. New ALMA data suggest that the disk around the star may be expelling gas via a wind.
On April 29, the European Space Agency announced that its premier infrared space observatory had run out of coolant and the mission had come to an end. Observing the cosmos in far-infrared wavelengths, the space telescope has given us some of the most striking views of cool nebulae, star forming regions, comets being pulverized around nearby stars, even asteroids buzzing around our own solar system. As we say goodbye to the historic mission, and astronomers continue to analyze the huge wealth of data Herschel has left us with, it's time to have a look back at some of the mission's most spectacular observations.
In this picture, embryonic stars feed on the gas and dust clouds deep inside the Orion Nebula. This image combines far-infrared data by Herschel and mid-infrared data by NASA's Spitzer space telescope.
The Andromeda galaxy in infrared -- Herschel took this portrait of the famous spiral galaxy, picking out the fine detail from gas and dust running through its structure.
This three-color image of the W3 giant molecular cloud combines Herschel's 70 μm (blue), 160 μm (green) and 250 μm (red) filters. W3 is located about 6200 light-years away and is a hub of intense star formation. Filaments of gas and dust cocooning protostars (yellow dots) can be seen.
The star Betelgeuse is observed in infrared by Herschel as it rapidly approaches a "barrier" of interstellar gas. The bow shock of the star's stellar winds can easily be seen.
The star Kappa Coronae Borealis is captured in this infrared observation by Herschel. The star itself is blocked out whereas the ring of debris (likely from asteroid/comet impacts) glows bright.
The infrared emissions from dust produced by a huge number of cometary collisions surrounding the famous star Fomalhaut glows in bright blue in Herschel's eye. At least one exoplanet is known to orbit within this ring of dust.
Supernova remnant W44 is the focus of this observation created by combining data from ESA's Herschel and XMM-Newton space observatories.
Herschel picks out 600 newly forming stars inside the W40 nebula cradle of stars -- located 1,000 light-years away in the constellation Aquila.
Herschel could also study solar system objects with ease. In this observation, asteroid Apophis was captured during its approach to Earth on 5/6 January 2013. This image shows the asteroid in Herschel’s three PACS wavelengths: 70, 100 and 160 microns, respectively.
This striking image complemented Hubble's 23rd anniversary optical view of the Horsehead Nebula. Herschel's infrared observation of the Orion Molecular Cloud complex (including the Horsehead Nebula -- visible far right of image) provided a unique perspective on this astronomical favorite.
Dense filaments of gas in the IC5146 interstellar cloud can be seen in this Herschel observation. Stars are forming along these filaments.