ABSTRACT From high resolution (R 45,000), high signal-to-noise ratio (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.
ABSTRACT
We present JWST images of the well-known planetary nebula NGC 6720 (the Ring Nebula), covering wavelengths from 1.6 to 25 $\, \mu$m. The bright shell is strongly fragmented with some 20 000 ...dense globules, bright in H2, with a characteristic diameter of 0.2 arcsec and density nH ∼ 105–106 cm−3. The shell contains a narrow ring of polycyclic aromatic hydrocarbon (PAH) emission. H2 is found throughout the shell and also in the halo. H2 in the halo may be located on the swept-up walls of a biconal polar flow. The central cavity is filled with high-ionization gas and shows two linear structures which we suggest are the edges of a biconal flow, seen in projection against the cavity. The central star is located 2 arcsec from the emission centroid of the cavity and shell. Linear features (‘spikes’) extend outward from the ring, pointing away from the central star. Hydrodynamical simulations reproduce the clumping and possibly the spikes. Around 10 low-contrast, regularly spaced concentric arc-like features are present; they suggest orbital modulation by a low-mass companion with a period of about 280 yr. A previously known much wider companion is located at a projected separation of about 15 000 au; we show that it is an M2–M4 dwarf. NGC 6720 is therefore a triple star system. These features, including the multiplicity, are similar to those seen in the Southern Ring Nebula (NGC 3132) and may be a common aspect of such nebulae.
IGRINS Slit-viewing Camera Software Lee, Hye-In; Pak, Soojong; Mace, Gregory N. ...
Publications of the Astronomical Society of the Pacific,
04/2020, Volume:
132, Issue:
1010
Journal Article
Peer reviewed
Open access
We have developed observation control software for the Immersion GRating INfrared Spectrometer (IGRINS) slit-viewing camera module, which maintains the position of an astronomical target on the ...spectroscopic slit. It is composed of several packages that monitor and control the system, acquire the images, and compensate for the tracking error by sending tracking feedback information to the telescope control system. For efficient development and maintenance of each software package, we have applied software engineering methods, i.e., a spiral software development with model-based design. It is not trivial to define the shape and center of astronomical object point spread functions (PSFs), which do not have symmetric Gaussian profiles in short exposure (<4 s) guiding images. Efforts to determine the PSF centroid are additionally complicated by the core saturation of bright guide stars. We have applied both a two-dimensional Gaussian fitting algorithm (2DGA) and center balancing algorithm (CBA) to identify an appropriate method for IGRINS in the near-infrared K-band. The CBA derives the expected center position along the slit-width by referencing the spillover flux ratio of the PSF wings on both sides of the slit. In this research, we have compared the accuracy and reliability of the CBA to the 2DGA by using data from IGRINS commissioning observations at McDonald Observatory. We find that the performance of each algorithm depends on the brightness of the targets and the seeing conditions, with the CBA performing better in typical observing scenarios. The algorithms and test results we present can be utilized with future spectroscopic slit observations in various observing conditions and for a variety of spectrograph designs.
We present a deep near-infrared spectrum of the Orion Bar Photodissociation Region (PDR) taken with the Immersion Grating INfrared Spectrometer (IGRINS) on the 2.7 m telescope at the McDonald ...Observatory. IGRINS has high spectral resolution (\(R\sim {\rm{45,000}}\)) and instantaneous broad wavelength coverage (1.45–2.45 μm), enabling us to detect 87 emission lines from rovibrationally excited molecular hydrogen (H2) that arise from transitions out of 69 upper rovibration levels of the electronic ground state. These levels cover a large range of rotational and vibrational quantum numbers and excitation energies, making them excellent probes of the excitation mechanisms of H2 and physical conditions within the PDR. The Orion Bar PDR is thought to consist of cooler high density clumps or filaments (\(T=50\mbox{--}250\) K, \({n}_{H}={10}^{5}\mbox{--}{10}^{7}\) cm−3) embedded in a warmer lower density medium (\(T=250\mbox{--}1000\) K, \({n}_{H}={10}^{4}\mbox{--}{10}^{5}\) cm−3). We fit a grid of constant temperature and density Cloudy models, which recreate the observed H2 level populations well, to constrain the temperature to a range of 600–650 K and the density to \({n}_{H}=2.5\times {10}^{3}\mbox{--}{10}^{4}\) cm−3. The best-fit model gives T = 625 K and \({n}_{H}=5\times {10}^{3}\) cm−3. This well-constrained warm temperature is consistent with kinetic temperatures found by other studies for the Orion Bar’s lower density medium. However, the range of densities well fit by the model grid is marginally lower than those reported by other studies. We could be observing lower density gas than the surrounding medium, or perhaps a density-sensitive parameter in our models is not properly estimated.
The Spectrum of SS 433 in the H and K Bands Robinson, Edward L.; Froning, Cynthia S.; Jaffe, Daniel T. ...
The Astrophysical journal,
06/2017, Volume:
841, Issue:
2
Journal Article
Peer reviewed
SS 433 is an X-ray binary and the source of sub-relativistic, precessing, baryonic jets. We present high-resolution spectrograms of SS 433 in the infrared H and K bands. The spectrum is dominated by ...hydrogen and helium emission lines. The precession phase of the emission lines from the jet continues to be described by a constant period, . The limit on any secularly changing period is . The He i line has complex and variable P-Cygni absorption features produced by an inhomogeneous wind with a maximum outflow velocity near 900 km s−1. The He ii emission lines in the spectrum also arise in this wind. The higher members of the hydrogen Brackett lines show a double-peaked profile with symmetric wings extending more than 1500 km s−1 from the line center. The lines display radial velocity variations in phase with the radial velocity variation expected of the compact star, and they show a distortion during disk eclipse that we interpret as a rotational distortion. We fit the line profiles with a model in which the emission comes from the surface of a symmetric, Keplerian accretion disk around the compact object. The outer edge of the disk has velocities that vary from 110 to 190 km s−1. These comparatively low velocities place an important constraint on the mass of the compact star: its mass must be less than and is probably less than .
We present a deep near-infrared spectrum of the Orion Bar Photodissociation Region (PDR) taken with the Immersion Grating INfrared Spectrometer (IGRINS) on the 2.7 m telescope at the McDonald ...Observatory. IGRINS has high spectral resolution ( R ∼ 45,000 ) and instantaneous broad wavelength coverage (1.45-2.45 m), enabling us to detect 87 emission lines from rovibrationally excited molecular hydrogen (H2) that arise from transitions out of 69 upper rovibration levels of the electronic ground state. These levels cover a large range of rotational and vibrational quantum numbers and excitation energies, making them excellent probes of the excitation mechanisms of H2 and physical conditions within the PDR. The Orion Bar PDR is thought to consist of cooler high density clumps or filaments ( T = 50 - 250 K, n H = 10 5 - 10 7 cm−3) embedded in a warmer lower density medium ( T = 250 - 1000 K, n H = 10 4 - 10 5 cm−3). We fit a grid of constant temperature and density Cloudy models, which recreate the observed H2 level populations well, to constrain the temperature to a range of 600-650 K and the density to n H = 2.5 × 10 3 - 10 4 cm−3. The best-fit model gives T = 625 K and n H = 5 × 10 3 cm−3. This well-constrained warm temperature is consistent with kinetic temperatures found by other studies for the Orion Bar's lower density medium. However, the range of densities well fit by the model grid is marginally lower than those reported by other studies. We could be observing lower density gas than the surrounding medium, or perhaps a density-sensitive parameter in our models is not properly estimated.
We present a high-resolution, near-IR spectroscopic study of multiple outflows in the LkHα 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 H2 and Fe ii emission. We show that the H2 emission represents not a single jet but rather complex multiple outflows driven by three known embedded sources: MM1, VLA 2, and VLA 3. There is a redshifted H2 outflow at a low velocity, V LSR <+50 km s−1, with respect to the systemic velocity of V LSR = −11.5 km s−1, that coincides with the H2O masers seen in earlier radio observations 2″ southwest of VLA 2. We found that the previously detected Fe ii jet with \(| {V}_{\mathrm{LSR}}| \,\gt \) 100 km s−1 driven by VLA 3B is also detected in H2 emission and confirm that this jet has a position angle of about 240°. Spectra of the redshifted knots at 14″–65″ northeast of LkHα 234 are presented for the first time. These spectra also provide clues to the existence of multiple outflows. We detected high-velocity (50–120 km s−1) H2 gas in the multiple outflows around LkHα 234. Since these gases move at speeds well over the dissociation velocity (>40 km s−1), the emission must originate from the jet itself rather than H2 gas in the ambient medium. Also, position–velocity and excitation diagrams indicate that emission from knot C in HH 167 comes from two different phenomena, shocks and photodissociation.
With the Blue Channel Spectrograph (BCS) on the MMT telescope, we have obtained spectra to the atmospheric cutoff of quasars previously known to show at least one absorption system at > 1.6 with very ...strong metal lines. We refer to these absorbers as candidate metal-strong damped Ly alpha systems (cMSDLAs), the majority of which were culled from the Sloan Digital Sky Survey. The BCS/MMT spectra yield precise estimates of the H i column densities of the systems through Voigt profile analysis of their Ly alpha transitions. Nearly all of the cMSDLAs (41/43) satisfy the criterion of DLAs, 10 atoms cm . As a population, these systems have systematically higher values than DLAs chosen randomly from quasar sightlines. Combining our measurements with previously measured metal column densities, we estimate metallicities for the MSDLAs. These systems have significantly higher values than randomly selected DLAs; at similar to 2 , the MSDLAs show a median metallicity M/H similar to -0.67 that is 0.6 dex higher than a corresponding control sample. This establishes MSDLAs as having among the most metal-rich gas in the high universe. Our measurements extend the observed correlation between Si II 1526 equivalent width and the gas metallicity to higher values. If interpreted as a mass-metallicity relation, this implies the MSDLAs are the high-mass subset of the DLA population. We demonstrate that dust in the MSDLAs reddens their background quasars, with a median shift in the spectral slope of Delta alpha = 0.29 . Assuming an SMC extinction law, this implies a median reddening similar to 0.025 mag and visual extinction similar to 0.076 mag . The latter quantity yields a dust-to-gas ratio of log(/) similar to -22.0 , very similar to estimation for the SMC. Future studies of MSDLAs offer the opportunity to study the extinction, nucleosynthesis, and kinematics of the most chemically evolved, gas-rich galaxies at high .
Abstract
BL Lacertae (Lac) objects that are detected at very high energies (VHE) are of fundamental importance to study multiple astrophysical processes, including the physics of jets, the properties ...of the extragalactic background light and the strength of the intergalactic magnetic field. Unfortunately, since most blazars have featureless optical spectra that preclude a redshift determination, a substantial fraction of these VHE extragalactic sources cannot be used for cosmological studies. To assess whether molecular lines are a viable way to establish distances, we have undertaken a pilot programme at the Institut of Millimétrique (IRAM) 30 m telescope to search for CO lines in three BL Lac objects with known redshifts. We report a positive detection of M⊙ towards 1ES 1959+650, but due to the poor quality of the baseline, this value is affected by a large systematic uncertainty. For the remaining two sources, W Comae and RGB J0710+591, we derive 3σ upper limits at, respectively, and 1.6 × 109 M⊙, assuming a line width of 150 km s−1 and a standard conversion factor α = 4 M⊙ (K km s−1 pc2)−1. If these low molecular gas masses are typical for blazars, blind redshift searches in molecular lines are currently unfeasible. However, deep observations are still a promising way to obtain precise redshifts for sources whose approximate distances are known via indirect methods. Our observations further reveal a deficiency of molecular gas in BL Lac objects compared to quasars, suggesting that the host galaxies of these two types of active galactic nuclei (AGN) are not drawn from the same parent population. Future observations are needed to assess whether this discrepancy is statistically significant, but our pilot programme shows how studies of the interstellar medium in AGN can provide key information to explore the connection between the active nuclei and the host galaxies.
Interprofessional collaboration (IPC) is the practice of two or more healthcare professionals working together and learning from one another to improve health outcomes. IPC is important for quality ...training, typically improving individual and group level outcomes. Students value the opportunity for leadership and teamwork development when IPC is offered in their curriculum. The Indiana University Student Outreach Clinic (IUSOC) is a student run clinic that provides free primary care services to underserved residents residing in Indianapolis, Indiana. The IUSOC partner leaders identified a need to enhance knowledge about partner roles, scope of practice, and professional training with the hopes of improving quality of care through IPC and utilization of clinic resources.
A cluster randomized design consisted of education session days and control days. Participants had an equal selection probability. Student partners from ten different disciplines were involved. Two survey instruments were used for data collection: 1) The Interprofessional Socialization and Valuing Scale and 2) The Professional Consciousness Raising Questionnaire. The former measured the attitudes and beliefs that underlie interprofessional socialization, while the latter assessed pre/post student knowledge of the roles and responsibilities of each partner.
The control arm of the study was composed of 167 student participants and the intervention arm had 170 participants. Participants in the intervention arm had greater scores for “ability to work with others”, “value in working with others”, and “comfort in working with others.” The intervention arm also had significantly increased odds of correctly identifying the roles responsibilities of the nursing, law, dental, and global health disciplines.
Results of this study demonstrate that administering a short interprofessional education exercise to healthcare professional students leads to improved IPC through increased interprofessional knowledge about other professions and change in beliefs and values toward the value of interprofessional collaboration among healthcare professionals.
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