Browsing by Subject "spectrograph"
Now showing 1 - 20 of 30
- Results Per Page
- Sort Options
Item The Black Hole Mass In The Brightest Cluster Galaxy NGC 6086(2011-02) McConnell, Nicholas J.; Ma, Chung-Pei; Graham, James R.; Gebhardt, Karl; Lauer, Tod R.; Wright, Shelley A.; Richstone, Douglas O.; Gebhardt, KarlWe present the first direct measurement of the central black hole mass, M-center dot, in NGC 6086, the Brightest Cluster Galaxy (BCG) in A2162. Our investigation demonstrates for the first time that stellar-dynamical measurements of M-center dot in BCGs are possible beyond the nearest few galaxy clusters. We observed NGC 6086 with laser guide star adaptive optics and the integral-field spectrograph (IFS) OSIRIS at the W. M. Keck Observatory and with the seeing-limited IFS GMOS-N at Gemini Observatory North. We combined the IFS data sets with existing major-axis kinematics and used axisymmetric stellar orbit models to determine M-center dot and the R-band stellar mass-to-light ratio, M-*/LR. We find M-center dot = 3.6(-1.1)(+1.7) x 10(9) M-circle dot and M-*/L-R = 4.6(-0.7)(+0.3) M-circle dot L-circle dot(-1) (68% confidence) from models using the most massive dark matter halo allowed within the gravitational potential of the host cluster. Models fitting only IFS data confirm M-center dot similar to 3x10(9) M circle dot and M-*/L-R similar to 4M(circle dot) L-circle dot(-1), with weak dependence on the assumed dark matter halo structure. When data out to 19 kpc are included, the unrealistic omission of dark matter causes the best-fit black hole mass to decrease dramatically, to 0.6 x 10(9) M-circle dot, and the best-fit stellar mass-to-light ratio to increase to 6.7 M circle dot L-(c),R(-1) . The latter value is at further odds with stellar population studies favoring M-*/L-R similar to 2M(circle dot) L-circle dot(-1) . Biases from dark matter omission could extend to dynamical models of other galaxies with stellar cores, and revised measurements of M-center dot could steepen the empirical scaling relationships between black holes and their host galaxies.Item A Catalog Of Near-Infrared Spectra From Type Ia Supernovae(2009-09) Marion, G. H.; Hoflich, P.; Gerardy, C. L.; Vacca, W. D.; Wheeler, J. C.; Robinson, E. L.; Marion, G. H.; Robinson, E. L.We present 41 near-infrared (NIR, 0.7-2.5 mu m) spectra from normal Type Ia supernovae (SNe Ia) obtained at epochs ranging from 14 days before to 75 days with respect to the maximum light date in the V band. All data were obtained at the Infrared Telescope Facility using the SpeX instrument. We identify many spectral features, measure the Doppler velocities, and discuss the chemical distribution of explosion products in SNe Ia. We describe procedures for smoothing data, fitting continua, and measuring absorption features to ensure consistency for measurement and analysis. This sample provides the first opportunity to examine and compare a large number of SNe Ia in this wavelength region. NIR data are a rich source of information about explosion products whose signatures are blended or obscured in other spectral regions and NIR observations probe a greater radial depth than optical wavelengths. We analyze similarities and differences in the spectra and we show that the progressive development of spectral features for normal SNe Ia in the NIR is consistent with time. We confirm the presence of O I, Mg II, Ca II, Si II, Fe II, and Co II in these SNe. Possible identifications are made for S I, Si III, Mn II, and Fe III. There is no evidence in these data for H I, He I, C I, or C II. As the explosion products expand and cool, progressively deeper layers are revealed. Thus, a time sequence of spectra examines the chemical structure and provides direct evidence of the physical properties of SNe Ia from the outer layers to deep inside the SN. Measured Doppler velocities indicate that burning products in SNe Ia are distributed in distinct layers with no large-scale mixing. Carbon is not detected in these data, in agreement with previous results with NIR data establishing very low limits on carbon abundance in SNe Ia. Carbon burning products, O and Mg, are plentiful in the outer layers suggesting that the entire progenitor is burned in the explosion. The data provide a resource for investigations of cross-correlations with other data libraries that may further constrain SN Ia physics and improve the effectiveness of SNe Ia as cosmological distance indicators.Item Constraints on Circumstellar Material Around the Type Ia Supernova 2007af(1,2)(2007-12) Simon, Joshua D.; Gal-Yam, Avishay; Penprase, Bryan E.; Li, Weidong; Quimby, Robert M.; Silverman, Jeffrey M.; Prieto, Carlos Allende; Wheeler, J. Craig; Filippenko, Alexei V.; Martinez, Irene T.; Beeler, Daniel J.; Patat, Ferdinando; Quimby, Robert M.; Prieto, Carlos Allende; Wheeler, J. CraigPatat et al. recently inferred the existence of circumstellar material around a normal Type Ia supernova (SN Ia) for the first time, finding time-variable Na I D absorption lines in the spectrum of SN 2006X. We present high-resolution spectroscopy of the bright SN Ia 2007af at three epochs and search for variability in any of the Na D absorption components. Over the time range from 4 days before to 24 days after maximum light, we find that the host-galaxy Na D lines appear to be of interstellar rather than circumstellar origin and do not vary down to the level of 18 m angstrom (column density of 2 x 10(11) cm(-2)). We limit any circumstellar absorption lines to be weaker than similar to 10 m angstrom (6 x 10(10) cm(-2)). For the case of material distributed in spherically symmetric shells of radius similar to 10(16) cm surrounding the progenitor system, we place an upper limit on the shell mass of similar to(3 x 10(-8))/X M circle dot, where X is the Na ionization fraction. We also show that SN 2007af is a photometrically and spectroscopically normal SN Ia. Assuming that the variable Na D lines in SN 2006X came from circumstellar matter, we therefore conclude that either there is a preferred geometry for the detection of variable absorption components in SNe Ia, or SN 2007af and SN 2006X had different types of progenitor systems.Item Detection of Water Vapor in the Terrestrial Planet Forming Region of a Transition Disk(2015-09) Salyk, Colette; Lacy, John H.; Richter, Matthew J.; Zhang, Ke; Blake, Geoffrey A.; Pontoppidan, Klaus M.; Lacy, John H.We report a detection of water vapor in the protoplanetary disk around DoAr 44 with the Texas Echelon Cross Echelle Spectrograph-a visitor instrument on the Gemini north telescope. The DoAr 44 disk consists of an optically thick inner ring and outer disk, separated by a dust-cleared 36 AU gap, and has therefore been termed "pre-transitional." To date, this is the only disk with a large inner gap known to harbor detectable quantities of warm ( T similar to 450 K) water vapor. In this work, we detect and spectrally resolve three mid-infrared pure rotational emission lines of water vapor from this source, and use the shapes of the emission lines to constrain the location of the water vapor. We find that the emission originates near 0.3 AU-the inner disk region. This characteristic region coincides with that inferred for both optically thick and thin thermal infrared dust emission, as well as rovibrational CO emission. The presence of water in the dust-depleted region implies substantial columns of hydrogen (> 1022 cm(-2)) as the water vapor would otherwise be destroyed by photodissociation. Combined with the dust modeling, this column implies a gas/small-dust ratio in the optically thin dusty region of. 1000. These results demonstrate that DoAr 44 has maintained similar physical and chemical conditions to classical protoplanetary disks in its terrestrial-planet forming regions, in spite of having formed a large gap.Item Discovery Of A Low-Mass Companion To The Solar-Type Star Tyc 2534-698-1(2009-02) Kane, Steven R.; Mahadevan, Suvrath; Cochran, William D.; Street, Rachel A.; Sivarani, Thirupathi; Henry, Gregory W.; Williamson, Michael H.; Cochran, William D.Brown dwarfs and low-mass stellar companions are interesting objects to study since they occupy the mass region between deuterium and hydrogen burning. We report here the serendipitous discovery of a low-mass companion in an eccentric orbit around a solar-type main-sequence star. The stellar primary, TYC 2534-698-1, is a G2V star that was monitored both spectroscopically and photometrically over the course of several months. Radial velocity observations indicate a minimum mass of 0.037 M(circle dot) and an orbital period of similar to 103 days for the companion. Photometry outside of the transit window shows the star to be stable to within similar to 6 millimags. The semimajor axis of the orbit places the companion in the "brown dwarf desert" and we discuss potential follow-up observations that could constrain the mass of the companion.Item Discovery Of Binarity, Spectroscopic Frequency Analysis, And Mode Identification Of The Delta Scuti Star 4 CVn(2014-10) Schmid, V. S.; Themessl, N.; Breger, M.; Degroote, P.; Aerts, C.; Beck, P. G.; Tkachenko, A.; Van Reeth, T.; Bloemen, S.; Debosscher, J.; Castanheira, B. G.; McArthur, B. E.; Papics, P. I.; Fritz, V.; Falcon, R. E.; Castanheira, B. G.; McArthur, B. E.; Falcon, R. E.More than 40 years of ground-based photometric observations of the delta Sct star 4 CVn has revealed 18 independent oscillation frequencies, including radial as well as non-radial p-modes of low spherical degree l <= 2. From 2008 to 2011, more than 2000 spectra were obtained at the 2.1m Otto-Struve telescope at the McDonald Observatory. We present the analysis of the line-profile variations, based on the Fourier-parameter fit method, detected in the absorption lines of 4 CVn, which carry clear signatures of the pulsations. From a non-sinusoidal, periodic variation of the radial velocities, we discover that 4 CVn is an eccentric binary system with an orbital period P-orb = 124.44 +/- 0.03 d and an eccentricity e = 0.311 +/- 0.003. We detect 20 oscillation frequencies, 9 of which previously unseen in photometric data; attempt mode identification for the two dominant modes, f(1) = 7.3764 d(-1) and f(2) = 5.8496 d(-1); and determine the prograde or retrograde nature of 7 of the modes. The projected rotational velocity of the star, v(eq) sin i similar or equal to 106.7 km s(-1), translates to a rotation rate of v(eq)/v(crit) >= 33%. This relatively high rotation rate hampers unique mode identification, since higher order effects of rotation are not included in the current methodology. We conclude that, in order to achieve unambiguous mode identification for 4CVn, a complete description of rotation and the use of blended lines have to be included in mode-identification techniques.Item Discovery Of Pulsations, Including Possible Pressure Modes, In Two New Extremely Low Mass, He-Core White Dwarfs(2013-03) Hermes, J. J.; Montgomery, Michael H.; Winget, D. E.; Brown, Warren R.; Gianninas, A.; Kilic, Mukremin; Kenyon, S. J.; Bell, Keaton J.; Harrold, Samuel T.; Hermes, J. J.; Montgomery, Michael H.; Winget, D. E.; Bell, Keaton J.; Harrold, Samuel T.We report the discovery of the second and third pulsating extremely low mass (ELM) white dwarfs (WDs), SDSS J111215.82+111745.0 (hereafter J1112) and SDSS J151826.68+065813.2 (hereafter J1518). Both have masses < 0.25 M-circle dot and effective temperatures below 10,000 K, establishing these putatively He-core WDs as a cooler class of pulsating hydrogen-atmosphere WDs (DAVs, or ZZ Ceti stars). The short-period pulsations evidenced in the light curve of J1112 may also represent the first observation of acoustic (p-mode) pulsations in any WD, which provide an exciting opportunity to probe this WD in a complimentary way compared to the long-period g-modes that are also present. J1112 is a T-eff = 9590 +/- 140 K and log g = 6.36 +/- 0.06 WD. The star displays sinusoidal variability at five distinct periodicities between 1792 and 2855 s. In this star, we also see short-period variability, strongest at 134.3 s, well short of the expected g-modes for such a low-mass WD. The other new pulsating WD, J1518, is a Teff = 9900 +/- 140 K and log g = 6.80 +/- 0.05 WD. The light curve of J1518 is highly non-sinusoidal, with at least seven significant periods between 1335 and 3848 s. Consistent with the expectation that ELM WDs must be formed in binaries, these two new pulsating He-core WDs, in addition to the prototype SDSS J184037.78+642312.3, have close companions. However, the observed variability is inconsistent with tidally induced pulsations and is so far best explained by the same hydrogen partial-ionization driving mechanism at work in classic C/O-core ZZ Ceti stars.Item Discovery, Progenitor and Early Evolution of A Stripped Envelope Supernova iPTF13bvn(2013-09) Cao, Yi; Kasliwal, Mansi M.; Arcavi, Iair; Horesh, Assaf; Hancock, Paul; Valenti, Stefano; Cenko, S. Bradley; Kulkarni, S. R.; Gal-Yam, Avishay; Gorbikov, Evgeny; Ofek, Eran O.; Sand, David; Yaron, Ofer; Graham, Melissa; Silverman, Jeffrey M.; Wheeler, J. Craig; Marion, G. H.; Walker, Emma S.; Mazzali, Paolo; Howell, D. Andrew; Li, K. L.; Kong, A. K. H.; Bloom, Joshua S.; Nugent, Peter E.; Surace, Jason; Masci, Frank; Carpenter, John; Degenaar, Nathalie; Gelino, Christopher R.; Silverman, Jeffrey M.; Wheeler, J. Craig; Marion, G. H.The intermediate Palomar Transient Factory reports our discovery of a young supernova, iPTF13bvn, in the nearby galaxy, NGC 5806 (22.5 Mpc). Our spectral sequence in the optical and infrared suggests a Type Ib classification. We identify a blue progenitor candidate in deep pre-explosion imaging within a 2 sigma error circle of 80 mas (8.7 pc). The candidate has an M-B luminosity of -5.52 +/- 0.39 mag and a B-I color of 0.25 +/- 0.25 mag. If confirmed by future observations, this would be the first direct detection for a progenitor of a Type Ib. Fitting a power law to the early light curve, we find an extrapolated explosion date around 0.6 days before our first detection. We see no evidence of shock cooling. The pre-explosion detection limits constrain the radius of the progenitor to be smaller than a few solar radii. iPTF13bvn is also detected in centimeter and millimeter wavelengths. Fitting a synchrotron self-absorption model to our radio data, we find a mass-loading parameter of 1.3x10(12) g cm(-1). Assuming a wind velocity of 10(3) km s(-1), we derive a progenitor mass-loss rate of 3 x 10(-5) M-circle dot yr(-1). Our observations, taken as a whole, are consistent with a Wolf-Rayet progenitor of the supernova iPTF13bvn.Item Early Observations And Analysis Of The Type Ia SN 2014J In M82(2015-01) Marion, G. H.; Sand, D. J.; Hsiao, Eric Y.; Banerjee, D. P. K.; Valenti, S.; Stritzinger, Maximillian D.; Vinko, Jozsef; Joshi, V.; Venkataraman, V.; Ashok, N. M.; Amanullah, R.; Binzel, R. P.; Bochanski, J. J.; Bryngelson, G. L.; Burns, Christopher R.; Drozdov, D.; Fieber-Beyer, S. K.; Graham, M. L.; Howell, D. Andrew; Johansson, J.; Kirshner, Robert P.; Milne, P. A.; Parrent, J.; Silverman, Jeffrey M.; Vervack Jr, R. J.; Wheeler, J. Craig; Marion, G. H.; Vinko, Jozsef; Silverman, Jeffrey M.; Wheeler, J. CraigWe present optical and near infrared (NIR) observations of the nearby Type Ia SN 2014J. Seventeen optical and 23 NIR spectra were obtained from 10 days before (-10d) to 10 days after (+10d) the time of maximum B-band brightness. The relative strengths of absorption features and their patterns of development can be compared at one day intervals throughout most of this period. Carbon is not detected in the optical spectra, but we identify C I lambda 1.0693 in the NIR spectra. Mg II lines with high oscillator strengths have higher initial velocities than other Mg II lines. We show that the velocity differences can be explained by differences in optical depths due to oscillator strengths. The spectra of SN 2014J show that it is a normal SN Ia, but many parameters are near the boundaries between normal and high-velocity subclasses. The velocities for OI, Mg II, Si II, S Ca a, and Fell suggest that SN 2014J has a layered structure with little or no mixing. That result is consistent with the delayed detonation explosion models. We also report photometric observations, obtained from -10d to +29d, in the UBVRIJH and K-s bands. The template fitting package SNooPy is used to interpret the light curves and to derive photometric parameters. Using R-v = 1.46, which is consistent with previous studies, SNooPy finds that A(v) = 1.80 for E(B - V)(host) = 1.23 +/- 0.06 mag. The maximum B-band brightness of -19.19 +/- 0.10 mag was reached on February 1.74 UT +/- 0.13 days and the supernova has a decline parameter, Delta m(15), of 1.12 +/- 0.02 mag.Item GMTNIRS (Giant Magellan Telescope Near-Infrared Spectrograph): Structural-Mechanical Design(2012-07) Beets, T.A.; Beno, J.H; Chun, M.Y; Lee, S; Park, C; Rafal, M; Worthington, M.S.A near-infrared spectrograph (NIRS) has been designed and proposed for utilization as a first-light instrument on the Giant Magellan Telescope (GMT). GMTNIRS includes modular JHK, LM spectrograph units mounted to two sides of a cryogenic optical bench. The optical bench and surrounding, protective radiation (thermal) shield are containerized within a rigid cryostat vessel, which mounts to the GMT instrument platform. A support structure on the secondary side of the optical bench provides multi-dimensional stiffness to the optical bench, to prevent excessive displacements of the optical components during tracking of the telescope. Extensive mechanical simulation and optimization was utilized to arrive at synergistic designs of the optical bench, support structure, cryostat, and thermal isolation system. Additionally, detailed steady-state and transient thermal analyses were conducted to optimize and verify the mechanical designs to maximize thermal efficiency and to size cryogenic coolers and conductors. This paper explains the mechanical and thermal design points stemming from optical component placement and mounting and structural and thermal characteristics needed to achieve instrument science requirements. The thermal and mechanical simulations will be described and the data will be summarized. Sufficient details of the analyses and data will be provided to validate the design decisions.Item H2O and OH Gas in the Terrestrial Planet-Forming Zones of Protoplanetary Disks(2008-03) Salyk, Colette; Pontoppidan, Klaus M.; Blake, Geoffrey A.; Lahuis, Fred; van Dishoeck, Ewine F.; Evans, Neal J., II; Evans, Neal J., IIWe present detections of numerous 10-20 mu m H(2)O emission lines from two protoplanetary disks around the T Tauri stars AS 205A and DR Tau, obtained using the InfraRed Spectrograph on the Spitzer Space Telescope. Followup 3-5 mu m Keck NIRSPEC data confirm the presence of abundant water and spectrally resolve the lines. We also detect the P4.5 (2.934 mu m) and P9.5 (3.179 mu m) doublets of OH and (12)CO/(13)CO nu = 1 -> 0 emission in both sources. Line shapes and LTE models suggest that the emission from all three molecules originates between similar to 0.5 and 5 AU, and so will provide a new window for understanding the chemical environment during terrestrial planet Formation. LTE models also imply significant columns of H(2)O and OH in the inner disk atmospheres, suggesting physical transport of volatile ices either vertically or radially, while the significant radial extent of the emission stresses the importance of a more complete understanding of nonthermal excitation processes.Item High-Velocity Line Forming Regions In The Type Ia Supernova 2009ig(2013-11) Marion, G. H.; Vinko, Jozsef; Wheeler, J. Craig; Foley, Ryan J.; Hsiao, Eric Y.; Brown, Peter J.; Challis, Peter; Filippenko, Alexei V.; Garnavich, Peter; Kirshner, Robert P.; Landsman, Wayne B.; Parrent, Jerod T.; Pritchard, Tyler A.; Roming, Peter W. A.; Silverman, Jeffrey M.; Wang, Xiaofeng; Marion, G. H.; Vinko, Jozsef; Wheeler, J. Craig; Silverman, Jeffrey M.We report measurements and analysis of high-velocity (HVF) (>20,000 km s(-1)) and photospheric absorption features in a series of spectra of the Type Ia supernova (SN) 2009ig obtained between -14 days and +13 days with respect to the time of maximum B-band luminosity (B-max). We identify lines of Si II, Si III, S II, Ca II, and Fe II that produce both HVF and photospheric-velocity (PVF) absorption features. SN 2009ig is unusual for the large number of lines with detectable HVF in the spectra, but the light-curve parameters correspond to a slightly overluminous but unexceptional SN Ia (M-B = -19.46 mag and Delta m(15)(B) = 0.90 mag). Similarly, the Si II lambda 6355 velocity at the time of B-max is greater than "normal" for an SN Ia, but it is not extreme (upsilon(Si) = 13,400 km s(-1)). The -14 days and -13 days spectra clearly resolve HVF from Si II lambda 6355 as separate absorptions from a detached line forming region. At these very early phases, detached HVF are prevalent in all lines. From -12 days to -6 days, HVF and PVF are detected simultaneously, and the two line forming regions maintain a constant separation of about 8000 km s(-1). After -6 days all absorption features are PVF. The observations of SN 2009ig provide a complete picture of the transition from HVF to PVF. Most SNe Ia show evidence for HVF from multiple lines in spectra obtained before -10 days, and we compare the spectra of SN 2009ig to observations of other SNe. We show that each of the unusual line profiles for Si II lambda 6355 found in early-time spectra of SNe Ia correlate to a specific phase in a common development sequence from HVF to PVF.Item How To Constrain Your M Dwarf: Measuring Effective Temperature, Bolometric Luminosity, Mass, And Radius(2015-05) Mann, Andrew W.; Feiden, Gregory A.; Gaidos, Eric; Boyajian, Tabetha; von Braun, Kaspar; Mann, Andrew W.Precise and accurate parameters for late-type (late K and M) dwarf stars are important for characterization of any orbiting planets, but such determinations have been hampered by these stars' complex spectra and dissimilarity to the Sun. We exploit an empirically calibrated method to estimate spectroscopic effective temperature (T-eff) and the Stefan-Boltzmann law to determine radii of 183 nearby K7-M7 single stars with a precision of 2%-5%. Our improved stellar parameters enable us to develop model-independent relations between Teff or absolute magnitude and radius, as well as between color and T-eff. The derived T-eff-radius relation depends strongly on [Fe/H], as predicted by theory. The relation between absolute K-S magnitude and radius can predict radii accurate to similar or equal to 3%. We derive bolometric corrections to the VR(C)I(C)grizJHK(S) and Gaia passbands as a function of color, accurate to 1%-3%. We confront the reliability of predictions from Dartmouth stellar evolution models using a Markov chain Monte Carlo to find the values of unobservable model parameters (mass, age) that best reproduce the observed effective temperature and bolometric flux while satisfying constraints on distance and metallicity as Bayesian priors. With the inferred masses we derive a semi-empirical mass-absolute magnitude relation with a scatter of 2% in mass. The best-agreement models overpredict stellar T-eff values by an average of 2.2% and underpredict stellar radii by 4.6%, similar to differences with values from low-mass eclipsing binaries. These differences are not correlated with metallicity, mass, or indicators of activity, suggesting issues with the underlying model assumptions, e.g., opacities or convective mixing length.Item Modification Of The MOOG Spectral Synthesis Codes To Account For Zeeman Broadening Of Spectral Lines(2013-09) Deen, Casey P.; Deen, Casey P.In an attempt to widen access to the study of magnetic fields in stellar astronomy, I present MOOGStokes, a version of the MOOG one-dimensional local thermodynamic equilibrium radiative transfer code, overhauled to incorporate a Stokes vector treatment of polarized radiation through a magnetic medium. MOOGStokes is a suite of three complementary programs, which together can synthesize the disk-averaged emergent spectrum of a star with a magnetic field. The first element (a pre-processing script called CounterPoint) calculates for a given magnetic field strength, wavelength shifts, and polarizations for the components of Zeeman-sensitive lines. The second element (a MOOG driver called SynStokes derived from the existing MOOG driver Synth) uses the list of Zeeman-shifted absorption lines together with the existing machinery of MOOG to synthesize the emergent spectrum at numerous locations across the stellar disk, accounting for stellar and magnetic field geometry. The third and final element (a post-processing script called DiskoBall) calculates the disk-averaged spectrum by weighting the individual emergent spectra by limb darkening and projected area, and applying the effects of Doppler broadening. All together, the MOOGStokes package allows users to synthesize emergent spectra of stars with magnetic fields in a familiar computational framework. MOOGStokes produces disk-averaged spectra for all Stokes vectors (I, Q, U, V), normalized by the continuum. MOOGStokes agrees well with the predictions of INVERS10 a polarized radiative transfer code with a long history of use in the study of stellar magnetic fields. In the non-magnetic limit, MOOGStokes also agrees with the predictions of the scalar version of MOOG.Item New Precision Orbits Of Bright Double-Lined Spectroscopic Binaries. III. HD 82191, Omega Draconis, And 108 Herculis(2009-04) Fekel, Francis C.; Tomkin, Jocelyn; Williamson, Michael H.; Fekel, Francis C.; Tomkin, Jocelyn; Williamson, Michael H.We have determined improved spectroscopic orbits for three double-lined binaries, HD 82191 (Am), omega Dra (F5 V), and 108 Her (Am), using radial velocities from the 2.1 m telescope at McDonald Observatory, the coude feed telescope at Kitt Peak National Observatory, and 2 m telescope at Fairborn Observatory. The orbital periods range from 5.28 to 9.01 days, and all three systems have circular orbits. The new orbital dimensions (a(1) sin i and a(2) sin i) and minimum masses (m(1) sin(3) i and m(2) sin(3) i) have accuracies of 0.2% or better. Our improved results confirm the large minimum masses of HD 82191 and also agree with the values previously found for. Dra. However, for the components of 108 Her our minimum masses are about 20% larger than the previous best values. We conclude that both components of HD 82191 as well as the primary of 108 Her are Am stars. However, the A9 secondary of 108 Her has normal abundances. We estimate spectral types of F4 dwarf and G0 dwarf for the components of. Dra. The primaries of the three binaries are synchronously rotating as is the secondary of 108 Her. The secondaries of HD 82191 and omega Dra are possibly synchronously rotating.Item New Precision Orbits Of Bright Double-Lined Spectroscopic Binaries. VIII. HR 1528, HR 6993, 2 Sagittae, And 18 Vulpeculae(2013-11) Fekel, Francis C.; Tomkin, Jocelyn; Williamson, Michael H.; Tomkin, JocelynImproved orbital elements for four A-star double-lined spectroscopic binaries have been determined with numerous new radial velocities. Three of the four systems, HR 1528, 2 Sge, and 18 Vul, have moderately short orbital periods of 7.05, 7.39, and 9.31 days, respectively, and also have circular or nearly circular orbits. Only HR 6993 with a period of 14.68 days has a significantly eccentric orbit. The close visual companion of 2 Sge has been detected spectroscopically, and its velocity measured. The orbital dimensions (a(1) sin i and a(2) sin i) and minimum masses (m(1) sin(3) i and m(2) sin(3) i) of the short-period binary components all have accuracies of 0.5% or better. We determine basic properties of the individual stars and compare them with solar-abundance evolutionary tracks to estimate their masses. Half of the eight components may be synchronously or pseudosynchronously rotating.Item New Precision Orbits Of Bright Double-Lined Spectroscopic Binaries. VIII. HR 1528, HR 6993, 2 Sagittae, And 18 Vulpeculae(2013-11) Fekel, Francis C.; Tomkin, Jocelyn; Williamson, Michael H.; Tomkin, JocelynImproved orbital elements for four A-star double-lined spectroscopic binaries have been determined with numerous new radial velocities. Three of the four systems, HR 1528, 2 Sge, and 18 Vul, have moderately short orbital periods of 7.05, 7.39, and 9.31 days, respectively, and also have circular or nearly circular orbits. Only HR 6993 with a period of 14.68 days has a significantly eccentric orbit. The close visual companion of 2 Sge has been detected spectroscopically, and its velocity measured. The orbital dimensions (a(1) sin i and a(2) sin i) and minimum masses (m(1) sin(3) i and m(2) sin(3) i) of the short-period binary components all have accuracies of 0.5% or better. We determine basic properties of the individual stars and compare them with solar-abundance evolutionary tracks to estimate their masses. Half of the eight components may be synchronously or pseudosynchronously rotating.Item Observations Of Type Ia Supernova 2014J With Flitecam On SOFIA(2015-05) Vacca, W. D.; Hamilton, R. T.; Savage, M.; Shenoy, S.; Becklin, E. E.; McLean, I. S.; Logsdon, S. E.; Marion, G. H.; Ashok, N. M.; Banerjee, D. P. K.; Evans, A.; Fox, O. D.; Garnavich, Peter; Gehrz, R. D.; Greenhouse, M.; Helton, L. A.; Kirshner, Robert P.; Shenoy, D.; Smith, N.; Spyromilio, J.; Starrfield, S.; Wooden, D. H.; Woodward, C. E.; Marion, G. H.We present medium-resolution near-infrared (NIR) spectra, covering 1.1-3.4 mu m, of the normal Type Ia supernova (SN Ia) SN 2014J in M82 obtained with the FLITECAM instrument on board Stratospheric Observatory for Infrared Astronomy (SOFIA) between 17 and 26 days after maximum B light. Our 2.8-3.4 mu m spectra may be the first similar to 3 mu m spectra of an SN Ia ever published. The spectra spanning the 1.5-2.7 mu m range are characterized by a strong emission feature at similar to 1.77 mu m with a FWHM of similar to 11,000-13,000 kms(-1). We compare the observed FLITECAM spectra to the recent non-LTE delayed detonation models of Dessart et al. and find that the models agree with the spectra remarkably well in the 1.5-2.7 mu m wavelength range. Based on this comparison we identify the similar to 1.77 mu m emission peak as a blend of permitted lines of Co II. Other features seen in the 2.0-2.5 mu m spectra are also identified as emission from permitted transitions of Co II. However, the models are not as successful at reproducing the spectra in the 1.1-1.4 mu m range or between 2.8 and 3.4 mu m. These observations demonstrate the promise of SOFIA, which allows access to wavelength regions inaccessible from the ground, and serve to draw attention to the usefulness of the regions between the standard ground-based NIR passbands for constraining SN models.Item On The Binary Helium Star DY Centauri: Chemical Composition And Evolutionary State(2014-10) Pandey, Gajendra; Rao, N. Kameswara; Jeffery, C. Simon; Lambert, David L.; Lambert, David L.DY Cen has shown a steady fading of its visual light by about one magnitude in the last 40 yr, suggesting a secular increase in its effective temperature. We have conducted non-local thermodynamic equilibrium (LTE) and LTE abundance analyses to determine the star's effective temperature, surface gravity, and chemical composition using high-resolution spectra obtained over two decades. The derived stellar parameters for three epochs suggest that DY Cen has evolved at a constant luminosity and has become hotter by about 5000 K in 23 yr. We show that the derived abundances remain unchanged for the three epochs. The derived abundances of the key elements, including F and Ne, are as observed for the extreme helium stars resulting from a merger of a He white dwarf with a C-O white dwarf. Thus DY Cen by chemical composition appears to also be a product of a merger of two white dwarfs. This appearance seems to be at odds with the recent suggestion that DY Cen is a single-lined spectroscopic binary.Item Precision Radial Velocities With CSHELL(2011-07) Crockett, Christopher J.; Mahmud, Naved I.; Prato, L.; Johns-Krull, Christopher M.; Jaffe, Daniel T.; Beichman, Charles A.; Jaffe, Daniel T.Radial velocity (RV) identification of extrasolar planets has historically been dominated by optical surveys. Interest in expanding exoplanet searches to M dwarfs and young stars, however, has motivated a push to improve the precision of near-infrared RV techniques. We present our methodology for achieving 58 m s(-1) precision in the K band on the M0 dwarf GJ 281 using the CSHELL spectrograph at the 3 m NASA Infrared Telescope Facility. We also demonstrate our ability to recover the known 4 M-JUP exoplanet Gl 86 b and discuss the implications for success in detecting planets around 1-3 Myr old T Tauri stars.