3 research outputs found
A 15 kpc outflow cone piercing through the halo of the blue compact metal-poor galaxy SBS0335-052
Context: Outflows from low-mass star-forming galaxies are a fundamental
ingredient for models of galaxy evolution and cosmology.
Aims: The onset of kpc-scale ionised filaments in the halo of the metal-poor
compact dwarf SBS 0335-052E was previously not linked to an outflow. We here we
investigate whether these filaments provide evidence for an outflow.
Methods: We obtained new VLT/MUSE WFM and deep NRAO/VLA B-configuration 21cm
data of the galaxy. The MUSE data provide morphology, kinematics, and emission
line ratios H/H and [\ion{O}{iii}]/H of the
low surface-brightness filaments, while the VLA data deliver morphology and
kinematics of the neutral gas in and around the system. Both datasets are used
in concert for comparisons between the ionised and the neutral phase.
Results: We report the prolongation of a lacy filamentary ionised structure
up to a projected distance of 16 kpc at erg s cmarcsec. The filaments exhibit
unusual low H/H and low [\ion{O}{iii}]/H typical of diffuse ionised gas. They are spectrally narrow ( km s) and exhibit no velocity sub-structure. The filaments extend
outwards of the elongated \ion{H}{I} halo. On small scales the
peak is offset from the main star-forming sites. Morphology and kinematics of
\ion{H}{I} and \ion{H}{II} reveal how star-formation driven feedback interacts
differently with the ionised and the neutral phase.
Conclusions: We reason that the filaments are a large scale manifestation of
star-formation driven feedback, namely limb-brightened edges of a giant outflow
cone that protrudes through the halo of this gas-rich system. A simple toy
model of such a conical-structure is found to be commensurable with the
observations.Comment: Accepted version in A&A after language editing. 22 pages, 24 figure
Physical properties of Centaur (60558) 174P/Echeclus from stellar occultations
The Centaur (60558) Echeclus was discovered on March 03, 2000, orbiting
between the orbits of Jupiter and Uranus. After exhibiting frequent outbursts,
it also received a comet designation, 174P. If the ejected material can be a
source of debris to form additional structures, studying the surroundings of an
active body like Echeclus can provide clues about the formation scenarios of
rings, jets, or dusty shells around small bodies. Stellar occultation is a
handy technique for this kind of investigation, as it can, from Earth-based
observations, detect small structures with low opacity around these objects.
Stellar occultation by Echeclus was predicted and observed in 2019, 2020, and
2021. We obtain upper detection limits of rings with widths larger than 0.5 km
and optical depth of = 0.02. These values are smaller than those of
Chariklo's main ring; in other words, a Chariklo-like ring would have been
detected. The occultation observed in 2020 provided two positive chords used to
derive the triaxial dimensions of Echeclus based on a 3D model and pole
orientation available in the literature. We obtained km, km, and km, resulting in an area-equivalent
radius of km. Using the projected limb at the occultation epoch
and the available absolute magnitude (), we
calculate an albedo of . Constraints on the
object's density and internal friction are also proposed.Comment: Corrected and typeset versio