72 research outputs found
Polarimetric modeling and assessment of science cases for Giant Magellan Telescope-Polarimeter (GMT-Pol)
Polarization observations through the next-generation large telescopes will
be invaluable for exploring the magnetic fields and composition of jets in AGN,
multi-messenger transients follow-up, and understanding interstellar dust and
magnetic fields. The 25m Giant Magellan Telescope (GMT) is one of the
next-generation large telescopes and is expected to have its first light in
2029. The telescope consists of a primary mirror and an adaptive secondary
mirror comprising seven circular segments. The telescope supports instruments
at both Nasmyth as well as Gregorian focus. However, none of the first or
second-generation instruments on GMT has the polarimetric capability. This
paper presents a detailed polarimetric modeling of the GMT for both Gregorian
and folded ports for astronomical B-K filter bands and a field of view of 5 arc
minutes. At 500nm, The instrumental polarization is 0.1% and 3% for the
Gregorian and folded port, respectively. The linear to circular crosstalk is
0.1% and 30% for the Gregorian and folded ports, respectively. The Gregorian
focus gives the GMT a significant competitive advantage over TMT and ELT for
sensitive polarimetry, as these telescopes support instruments only on the
Nasmyth platform. We also discuss a list of polarimetric science cases and
assess science case requirements vs. the modeling results. Finally, we discuss
the possible routes for polarimetry with GMT and show the preliminary optical
design of the GMT polarimeter.Comment: 13 pages, 5 figures,SPIE Optics + Photonics 2023 conference
proceeding, Paper no 12690-2
Crystalline Silicate Emission in the Protostellar Binary Serpens--SVS20
We present spatially resolved mid-infrared spectroscopy of the class
I/flat-spectrum protostellar binary system SVS20 in the Serpens cloud core. The
spectra were obtained with the mid-infrared instrument T-ReCS on Gemini-South.
SVS20-South, the more luminous of the two sources, exhibits a mid-infrared
emission spectrum peaking near 11.3 \micron, while SVS20-North exhibits a
shallow amorphous silicate absorption spectrum with a peak optical depth of
. After removal of the the line-of-sight extinction by the
molecular common envelope, the ``protostar-only'' spectra are found to be
dominated by strong amorphous olivine emission peaking near 10 \micron. We also
find evidence for emission from crystalline forsterite and enstatite associated
with both SVS20-S and SVS20-N. The presence of crystalline silicate in such a
young binary system indicates that the grain processing found in more evolved
HAeBe and T Tauri pre-main sequence stars likely begins at a relatively young
evolutionary stage, while mass accretion is still ongoing.Comment: Accepted for publication by The Astrophysical Journa
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