Bizarre Time Delay Discovered in Stellar Jets

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Stellar nurseries are chock-full of energetic phenomena as stars of all sizes coalesce out of the surrounding gas. It’s no wonder that we are always finding new and bizarre things in star-forming regions.

Take, for example, these jets coming out of either side of a baby star. Though one might assume these twin jets to be symmetric, it seems as though there is a strange time delay in the one shown above.

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As stars form out the compact gas in stellar nurseries, they often form disks of material (called accretion disks) that allow matter to spiral inwards toward the star, adding to its bulk. However, not all the gas makes it, as some can be blown away by strong stellar winds or by jets of material.

These jets can collide with the surrounding material at supersonic speeds, creating a beautiful glowing nebulosity. These have been named “Herbig-Haro objects” after their co-discoverers.

On the left in the image above, we have Herbig-Haro 34 as seen with visible light with the Very Large Telescope in Chile. Only one of the jets can be seen as the other is obscured by a dark cloud of dust. However, dust is no match for an infrared telescope, as NASA’s Spitzer Space Telescope allowed astronomers to finally study both jets coming from the star.

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The jets, shown on the right side of the top image, are symmetrical in almost every way. The difference? Four and a half days, apparently. Identical “knots” in the jets show up 4.5 years later on one side than on the other! This helps astronomers to constrain the size of the active region around the forming star which is producing these outbursts. It can never be just a simple picture.

This is the first time such a delay has been detected. Since Spitzer ended its main mission when the coolant ran out as scheduled, these wavelengths of infrared light are no longer accessible to the telescope. However, all of the data is archived and available for astronomers to comb for decades, and future work will include looking more closely at other Herbig-Haro objects to see if they have time delays as well.

Until we can actually travel back in time in Dr Who’s TARDIS, we’ll be using these baby stars as a model for what our sun was like in its earliest days.

Image: A baby star’s jets, named Herbig-Haro 34, in visible (left) and infrared (right) light. Credit: ESO/VLT; NASA/JPL-Caltech