“The Gemini data are the best ever obtained
from the ground of this remarkable jet complex and are showing us striking new detail”,
says Aspin. Reipurth and Aspin add that they
are particularly interested in the fine structure and “excitation distribution” of these jets.
“One jet is highly disturbed, suggesting that
the source may be a close binary whose orbit perturbs the jet body”, says Reipurth.
The researchers report that the jet complex
emanates from SSV63 — a Class I protostar
system, which high-resolution infrared imaging reveals to have at least five components. More sources are found in this region,
but only at longer, submillimeter wavelengths of light, suggesting that there are
even younger, and more deeply embedded
sources in the region. All of these embedded
sources are located within the dense molecular cloud core.
A search for dim optical and infrared young
stars has revealed several faint optical stars
located well outside the star-forming core.
In particular, GMOS found a halo of five faint
hydrogen-alpha (H-alpha) emission stars
(which emit large amounts of red light) surrounding the HH 24 Complex well outside
the dense cloud core. Gemini spectroscopy
October 2015
of the H-alpha emission stars show that they
are early or mid-M dwarfs (stars with very
low mass), at least one of which being a borderline brown dwarf.
The presence of these five stars well outside
the star-forming cloud core is puzzling, because the gas there is far too tenuous for star
formation. Instead they are likely orphan
protostars ejected shortly after birth from
the nearby star-forming core. Such ejections
occur when many stars form closely together within the same cloud core. The crowded
stars start moving around each other in a
chaotic dance. This ultimately leads to the
ejection of the smallest ones.
A consequence of such ejections is that pairs
of the remaining protostars bind together
gravitationally. The dense gas that surrounds the newly formed pairs brakes their
motion, so they gradually spiral together to
form tight binary systems with highly eccentric orbits. Each time the two components
are closest in their orbits they disturb each
other, leading to accretion of gas, and an
outflow event that we see as supersonic jets.
The many knots in the jets thus represent a
series of such perturbations.
GeminiFocus
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