Scientists using the Gaia telescope have captured hidden satellites of bright stars for the first time
Kyiv • UNN
Scientists have captured the hidden satellites of eight bright stars for the first time, combining observations from the Gaia space telescope and ground-based the GRAVITY instrument.
The combination of observations of the Gaia space telescope and ground-based instrument Gravity allowed scientists to capture the satellites of eight bright stars, which were not detected earlier. Writes UNN with reference to the publication Space.
Details
An international team of astronomers led by Thomas Winterhalder, a scientist at the European Southern Observatory (ESO) has been able to overcome the difficulty of observing small stars or planets near a bright star. Using the ground-based GRAVITY instrument, an advanced near-infrared interferometer located atop Cerro Paranal in Chile, as well as several Gaia telescopes, the researchers detected light signals from satellites around eight bright stars. Seven of the objects examined were theoretical and undetected until now.
Satellites of stars
Three companion objects are small and faint stars, while the remaining five are brown dwarfs. The latter form as stars and have more mass than the giant planets, but they do not have enough mass to start the process of fusing hydrogen and helium in their cores, as main-sequence stars do. This is where their nickname "failed stars" comes from.
We have shown that it is possible to image a faint satellite even if it orbits very close to its bright host
Hidden object can be recognized for the first time
One of the brown dwarfs discovered in this study orbits its parent star at the same distance as Earth is from the Sun.
This is the first time a brown dwarf can be directly imaged so close to its parent star.
Method of detection
It is important to consider that Gaia cannot directly detect dim stellar satellites, but the space telescope was able to infer their presence.
A brown dwarf or small star orbits around a larger and brighter star and its gravity attracts the parent star and this causes a "wobble" in the motion of the larger and brighter star.
As this star "wobbles" away from Earth (and Gaia), the wavelengths of light are stretched, shifting it toward the red end of the electromagnetic spectrum. Conversely, as it wobbles toward Earth, the wavelengths of light shorten, shifting the light toward the blue end of the electromagnetic spectrum.
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This redshift and blueshift effect is similar to Doppler shift, a phenomenon that affects sound waves on Earth. For example, when an ambulance approaches you with its siren blaring, the sound waves are compressed and the tone of the siren becomes higher, which is similar to the blue shift. When the ambulance passes you, the sound wavelengths expand and the siren tone becomes low, like the redshift of a star's light as it moves away.
Team Gaia and GRAVITY
According to Winterhalder, the current achievement "highlights the remarkable synergy between the Gaia telescope and the GRAVITY instrument.
"Only Gaia can identify such dense systems with a star and a 'hidden' companion, and then GRAVITY can take on the task of imaging the smaller and fainter object with unprecedented accuracy" he says.
The complementarity of Gaia and GRAVITY goes beyond using Gaia data to plan observations and provide detection. Thus, by combining the two data sets, the scientists were able to "weigh" individual celestial objects separately and differentiate between the mass of the parent star and the mass of its corresponding companion.
The ability to detect the tiny motions of close pairs in the sky is unique to the Gaia mission. The next catalog, which will be available as part of the fourth data release (DR4), will contain an even richer collection of stars with potentially smaller companions
