Using the Gemini Multi-conjugate Adaptive Optics System (GeMS) and the Gemini South Adaptive Optics Imager (GSAOI) on the 8.1-m Gemini South telescope on Cerro Pachón on the edge of the Chilean Andes, astronomers have captured images of two wiggling stellar jets: MHO 2147 and MHO 1502.
“Stellar jets and molecular outflows are ubiquitous in star-forming regions to such an extent that they are considered to be signposts of newly formed stars,” said lead author Dr. Leticia Ferrero, an astronomer at the Universidad Nacional de Córdoba and CONICET and her colleagues.
“Furthermore, they are usually associated with the earliest stages of stellar formation, when the incipient proto-stellar object is deeply embedded within a dense core of dust and molecular gas.”
“In the optical and near-infrared ranges, jets usually consist of a chain of knots with a terminal leading bow shock emanating from the young star and propagating away at high supersonic speeds.”
“Although most jets are straight or collimated, others have curved shapes.”
“Different mechanisms can produce the non-straight jets, such as the interstellar magnetic field, which curves or bends the jet axis. In addition, the stellar magnetosphere or magnetized disc can yield asymmetries in the jet.”
“In other cases, the wiggling profile may indicate that the jet axis wanders (precesses), or that the exciting source of the jet undergoes orbital motion.”
“The shape of a non-straight or wandering jet axis may be related to some characteristics of the central object. For example, reflection-symmetric wiggles may be due to the orbital motion of the jet source that belongs to a binary system, whereas the precession of the jet axis could produce a point-symmetric S-shaped jet induced by a tidal effect caused by a companion star in an orbit not coplanar to the disk.”
“With the aim of investigating the likely cause-effect relation between the wiggling morphology of stellar jets and the central star properties, we present high-resolution images obtained with GSAOI and GeMS of MHO 1502 and MHO 2147.”
MHO 2147 is roughly 10,000 light-years from Earth, and lies in the Galactic plane, close to the boundary between the constellations of Sagittarius and Ophiuchus.
The MHO 1502 jet is located approximately 2,000 light-years away in the constellation of Vela.
In the case of MHO 2147, the young central star — named IRAS 17527-2439 — is embedded in an infrared dark cloud.
The sinuous shape of the jet is caused because its direction has changed over time, tracing out a gentle curve on either side of the central star.
These almost unbroken curves suggest that MHO 2147 has been sculpted by continuous emission from its central source.
“We found that the changing direction of the jet may be due to the gravitational influence of nearby stars acting on the central star,” the astronomers said.
“Our observations suggest that IRAS 17527-2439 could belong to a triple star system separated by more than 300 billion km (almost 200 billion miles).”
MHO 1502, on the other hand, is embedded in a totally different environment — an area of star formation known as an HII region.
“MHO 1502 is composed of a chain of knots delineating the wiggling jet, suggesting that the driving source emitted them in an intermittent manner,” the researchers said.
“Our image of the previously proposed exciting star, IRAC 18064, shows two sources separated by 240 AU (astronomical units), hinting at its binarity.”
“However, as IRAC 18064 is located off the jet axis at 2,064 AU, it is questionable as to whether this source is the true exciting star.”
“Moreover, the orbital model centered on IRAC 18064 suggests a binary companion at a much greater distance (2,200 AU) than the nearby star (at 240 AU).”
The findings were published in the journal Astronomy and Astrophysics.
L.V. Ferrero et al. 2022. High-resolution images of two wiggling stellar jets, MHO 1502 and MHO 2147, obtained with GSAOI+GeMS. A&A 657, A110; doi: 10.1051/0004-6361/202142421
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