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Ultrastable environment control for the NEID spectrometer: design and performance demonstration
Two key areas of emphasis in contemporary experimental exoplanet science are the detailed characterization of transiting terrestrial planets and the search for Earth analog planets to be targeted by future imaging missions. Both of these pursuits are dependent on an order-of-magnitude improvement in the measurement of stellar radial velocities (RV), setting a requirement on single-measurement instrumental uncertainty of order 10 cm/s. Achieving such extraordinary precision on a high-resolution spectrometer requires thermomechanically stabilizing the instrument to unprecedented levels. We describe the environment control system (ECS) of the NEID spectrometer, which will be commissioned on the 3.5-m WIYN Telescope at Kitt Peak National Observatory in 2019, and has a performance specification of on-sky RV precision <50 cm/s. Because NEID's optical table and mounts are made from aluminum, which has a high coefficient of thermal expansion, sub-milliKelvin temperature control is especially critical. NEID inherits its ECS from that of the Habitable-Zone Planet Finder (HPF), but with modifications for improved performance and operation near room temperature. Our full-system stability test shows the NEID system exceeds the already impressive performance of HPF, maintaining vacuum pressures below 10(-6) Torr and a root mean square (RMS) temperature stability better than 0.4 mK over 30 days. Our ECS design is fully open-source; the design of our temperature-controlled vacuum chamber has already been made public, and here we release the electrical schematics for our custom temperature monitoring and control system. (C) 2019 Society of Photo-Optical Instrumentation Engineers (SPIE)JPL [1547612]; Center for Exoplanets and Habitable Worlds; Pennsylvania State University; Eberly College of Science; Pennsylvania Space Grant Consortium; NASA through the Sagan Fellowship Program by the NASA Exoplanet Science Institute; NASA Headquarters under the NASA Earth and Space Science Fellowship Program [NNX16AO28H]; NSF [AST-1006676, AST-1126413, AST-1310885]; NASA Astrobiology Institute (NAI) [NNA09DA76A]; Penn State Astrobiology Research CenterThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]
Neutron-Capture elements in planetary nebulae: first detections of near-Infrared [Te III] and [Br V] emission lines
We have identified two new near-infrared emission lines in the spectra of
planetary nebulae (PNe) arising from heavy elements produced by neutron capture
reactions: [Te III] 2.1019 m and [Br V] 1.6429 m. [Te III] was
detected in both NGC 7027 and IC 418, while [Br V] was seen in NGC 7027. The
observations were obtained with the medium-resolution spectrograph EMIR on the
10.4m Gran Telescopio Canarias at La Palma, and with the high-resolution
spectrograph IGRINS on the 2.7m Harlan J. Smith telescope at McDonald
Observatory. New calculations of atomic data for these ions, specifically
A-values and collision strengths, are presented and used to derive ionic
abundances of Te and Br. We also derive ionic abundances of other
neutron-capture elements detected in the near-infrared spectra, and estimate
total elemental abundances of Se, Br, Kr, Rb, and Te after correcting for
unobserved ions. Comparison of our derived enrichments to theoretical
predictions from AGB evolutionary models shows reasonable agreement for solar
metallicity progenitor stars of 2 - 4 M. The
spectrally-isolated [Br V] 1.6429 m line has advantages for determining
nebular Br abundances over optical [Br III] emission lines that can be blended
with other features. Finally, measurements of Te are of special interest
because this element lies beyond the first peak of the s-process, and thus
provides new leverage on the abundance pattern of trans-iron species produced
by AGB stars.Comment: 9 pages, 1 figure, 4 tables. Accepted for publication in ApJ Letter
The Chemical Compositions of Very Metal-Poor Stars HD 122563 and HD 140283; A View From the Infrared
From high resolution (R = 45,000), high signal-to-noise (S/N > 400) spectra
gathered with the Immersion Grating Infrared Spectrograph (IGRINS) in the H and
K photometric bands, we have derived elemental abundances of two bright,
well-known metal-poor halo stars: the red giant HD 122563 and the subgiant HD
140283. Since these stars have metallicities approaching [Fe/H] = -3, their
absorption features are generally very weak. Neutral-species lines of Mg, Si, S
and Ca are detectable, as well as those of the light odd-Z elements Na and Al.
The derived IR-based abundances agree with those obtained from
optical-wavelength spectra. For Mg and Si the abundances from the infrared
transitions are improvements to those derived from shorter wavelength data.
Many useful OH and CO lines can be detected in the IGRINS HD 122563 spectrum,
from which derived O and C abundances are consistent to those obtained from the
traditional [O I] and CH features. IGRINS high resolutions H- and K-band
spectroscopy offers promising ways to determine more reliable abundances for
additional metal-poor stars whose optical features are either not detectable,
or too weak, or are based on lines with analytical difficulties.Comment: Accepted for publication in ApJ (28 pages, 4 tables, 6 figures
High-resolution near-IR Spectral mapping with H and [Fe II] lines of Multiple Outflows around LkH 234
We present a high-resolution, near-IR spectroscopic study of multiple
outflows in the LkH 234 star formation region using the Immersion
GRating INfrared Spectrometer (IGRINS). Spectral mapping over the blueshifted
emission of HH 167 allowed us to distinguish at least three separate, spatially
overlapped, outflows in H and [Fe II] emission. We show that the H
emission represents not a single jet, but complex multiple outflows driven by
three known embedded sources: MM1, VLA 2, and VLA 3. There is a redshifted
H outflow at a low velocity, \VLSR 50 {\kms}, with respect to
the systemic velocity of \VLSR 11.5 {\kms}, that coincides with the
HO masers seen in earlier radio observations two arcseconds southwest of
VLA 2. We found that the previously detected [Fe II] jet with \VLSR
100 {\kms} driven by VLA 3B is also detected in H emission, and confirm
that this jet has a position angle about 240. Spectra of the
redshifted knots at 14\arcsec65\arcsec northeast of LkH 234 are
presented for the first time. These spectra also provide clues to the existence
of multiple outflows. We detected high-velocity (50120 {\kms}) H gas
in the multiple outflows around LkH 234. Since these gases move at
speeds well over the dissociation velocity ( 40 {\kms}), the emission must
originate from the jet itself rather than H gas in the ambient medium.
Also, position-velocity diagrams and excitation diagram indicate that emission
from knot C in HH 167 come from two different phenomena, shocks and
photodissociation.Comment: 32 pages, 12 figures, 2 tables, Accepted for publication in the
Astrophysical Journa
A Survey of UV Bright Sources Behind the Halo of M31
We have performed a wide-area ultraviolet (UV) imaging survey using the
GALaxy Evolution eXplorer (GALEX) to search for bright, point-like UV sources
behind M31's extended halo. Our survey consisted of 46 pointings covering an
effective area of ~50 deg^2, in both the far-UV and near-UV channels. We
combined these data with optical R-band observations acquired with the WIYN
Mosaic-1 imager on the Kitt Peak National Observatory 0.9m WIYN telescope. An
analysis of the brightness and colors of sources matched between our
photometric catalogs yielded ~100 UV-bright quasar candidates. We have obtained
discovery spectra for 76 of these targets with the Kast spectrometer on the
Lick 3m telescope and confirm 30 active galactic nuclei and quasars, 29
galaxies at z > 0.02 including several early-type systems, 16 Galactic stars
(hot main-sequence stars), and one featureless source previously identified as
a BL Lac object. Future UV spectroscopy of the brightest targets with the
Cosmic Origins Spectrograph on the Hubble Space Telescope will enable a
systematic search for diffuse gas in the extended halo of M31.Comment: 10 pages, 10 figures. Accepted to MNRA
The VIRUS-P Exploration of Nearby Galaxies (VENGA): Spatially resolved gas-phase metallicity distributions in barred and unbarred spirals
We present a study of the excitation conditions and metallicity of ionized gas (Zgas) in eight nearby barred and unbarred spiral galaxies from the VIRUS-P Exploration of Nearby Galaxies (VENGA) survey, which provides high spatial sampling and resolution (median ∼387 pc), large coverage from the bulge to outer disc, broad wavelength range (3600–6800 Å), and medium spectral resolution (∼120 km s−1 at 5000 Å). Our results are: (1) We present high resolution gas excitation maps to differentiate between regions with excitation typical of Seyfert, LINER, or recent star formation. We find LINER-type excitation at large distances (3–10 kpc) from the centre, and associate this excitation with diffuse ionized gas (DIG). (2) After excluding spaxels dominated by Seyfert, LINER, or DIG, we produce maps with the best spatial resolution and sampling to date of the ionization parameter q, star formation rate, and Zgas using common strong line diagnostics. We find that isolated barred and unbarred spirals exhibit similarly shallow Zgas profiles from the inner kpc out to large radii (7–10 kpc or 0.5–1.0 R25). This implies that if profiles had steeper gradients at earlier epochs, then the present-day bar is not the primary driver flattening gradients over time. This result contradicts earlier claims, but agrees with recent IFU studies. (3) The Zgas gradients in our z ∼ 0 massive spirals are markedly shallower, by ∼0.2 dex kpc−1, than published gradients for lensed lower mass galaxies at z ∼ 1.5–2.0. Cosmologically motivated hydrodynamical simulations best match this inferred evolution, but the match is sensitive to adopted stellar feedback prescriptions
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