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DOE OSTI2022

Measuring the mass of the black widow PSR J1555-2908

ABSTRACT Accurate measurements of the masses of neutron stars are necessary to test binary evolution models, and to constrain the neutron star equation of state. In pulsar binaries with no measurable post-Keplerian parameters, this requires an accurate estimate of the binary system’s inclination and the radial velocity of the companion star by other means than pulsar timing. In this paper, we present the results of a new method for measuring this radial velocity using the binary synthesis code Icarus. This method relies on constructing a model spectrum of a tidally distorted, irradiated star as viewed for a given binary configuration. This method is applied to optical spectra of the newly discovered black widow PSR J1555–2908. By modeling the optical spectroscopy alongside optical photometry, we find that the radial velocity of the companion star is 397 ± 4 km s−1 (errors quoted at 95 per cent confidence interval), as well as a binary inclination of >75°. Combined with γ-ray pulsation timing information, this gives a neutron star mass of 1.67$^{+0.15}_{-0.09}$ M⊙ and a companion mass of 0.060$^{+0.005}_{-0.003}$ M⊙, placing PSR J1555–2908 at the observed upper limit of what is considered a black widow system.

Kennedy, M. R.↗

NASA NTRS1972

On the nature of X Persei - Evidence from the 1957 outburst.

Discussion of the line identifications, radial velocities, and equivalent widths derived from spectrograms obtained with the University of Michigan 37-1/2-in. reflector and two-prism spectrograph between November 1954 and March 1960 by several observers. In mid-1957, there occurred in the spectrum of the O star X Per abrupt changes in the emission-line radial velocities and V/R ratios. The irregular variation of the V/R ratio, also observed in the past, suggests the occasional interruption of a more or less steady infall of material through the rotating emission region by outbursts of material from the star. The space velocity of X Per has been rederived, using a revised radial velocity, and compared to the space velocity of the runaway O star xi Per.

Wackerling, L. R.↗

NASA NTRS2022

Three New Brown Dwarfs and A Massive Hot Jupiter Revealed By TESS Around Early-Type Stars

Context. The detection and characterization of exoplanets and brown dwarfs around massive AF-type stars is essential to investigate and constrain the impact of stellar mass on planet properties. However, such targets are still poorly explored in radial velocity (RV) surveys because they only feature a small number of stellar lines and those are usually broadened and blended by stellar rotation as well as stellar jitter. As a result, the available information about the formation and evolution of planets and brown dwarfs around hot stars is limited. Aims. We aim to increase the sample and precisely measure the masses and eccentricities of giant planets and brown dwarfs transiting early-type stars detected by the Transiting Exoplanet Survey Satellite (TESS). Methods. We followed bright (V < 12 mag) stars with T eff > 6200 K that host giant companions (R > 7 R ⊕ ) using ground-based photometric observations as well as high precision radial velocity measurements from the CORALIE, CHIRON, TRES, FEROS, and MINERVA-Australis spectrographs. Results. In the context of the search for exoplanets and brown dwarfs around early-type stars, we present the discovery of three brown dwarf companions, TOI-629b, TOI-1982b, and TOI-2543b, and one massive planet, TOI-1107b. From the joint analysis of TESS and ground-based photometry in combination with high precision radial velocity measurements, we find the brown dwarfs have masses between 66 and 68 M Jup , periods between 7.54 and 17.17 days, and radii between 0.95 and 1.11 R Jup . The hot Jupiter TOI-1107b has an orbital period of 4.08 days, a radius of 1.30 R Jup , and a mass of 3.35 M Jup . As a by-product of this program, we identified four low-mass eclipsing components (TOI-288b, TOI-446b, TOI-478b, and TOI-764b). Conclusions. Both TOI-1107b and TOI-1982b present an anomalously inflated radius with respect to the age of these systems. TOI-629 is among the hottest stars with a known transiting brown dwarf. TOI-629b and TOI-1982b are among the most eccentric brown dwarfs. The massive planet and the three brown dwarfs add to the growing population of well-characterized giant planets and brown dwarfs transiting AF-type stars and they reduce the apparent paucity.

brown dwarfs↗

DOE OSTI2024

Filamentary velocity scaling validation and spin dynamics in the DIII-D tokamak

Measured filament velocities in the DIII-D tokamak are compared against theoretical scalings, finding that the latter often represents an upper limit on experimental velocity distributions with most filaments possessing lower velocity. Filament spin from internal E × B drift is experimentally demonstrated to alter filament radial velocity. A critical spin velocity, where filament radial velocity peaks, is observed and corresponds to approximately 5 km/s. This transition is corroborated using a less direct measure of filament spin in the form of a temperature ratio. These techniques are combined to find that the critical spin velocity closely aligns with transport times along and across filaments becoming comparable. The normalized filament size distribution is consistent with the most stable size as dictated by Kelvin–Helmholtz and curvature-driven instabilities. Overall, the findings suggest filament stability and spin alter filamentary transport that may threaten the integrity of first walls in fusion devices.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗

NASA NTRS2021

TOI-674b: An oasis in the desert of exo-Neptunes transiting a nearby M dwarf

Context. The NASA mission TESS is currently doing an all-sky survey from space to detect transiting planets around bright stars. As part of the validation process, the most promising planet candidates need to be confirmed and characterized using follow-up observations. Aims. In this article, our aim is to confirm the planetary nature of the transiting planet candidate TOI-674b using spectroscopic and photometric observations. Methods. We use TESS, Spitzer, ground-based light curves, and HARPS spectrograph radial velocity measurements to establish the physical properties of the transiting exoplanet candidate TOI-674b. We perform a joint fit of the light curves and radial velocity time series to measure the mass, radius, and orbital parameters of the candidate. Results. We confirm and characterize TOI-674b, a low-density super-Neptune transiting a nearby M dwarf. The host star (TIC 158588995, V = 14.2 mag, J = 10.3 mag) is characterized by its M2V spectral type with M⋆ = 0.420 ± 0.010 Mꙩ, R⋆ = 0.420 ± 0.013 Rꙩ, and T(eff) = 3514 ± 57 K; it is located at a distance d = 46.16 ± 0.03 pc. Combining the available transit light curves plus radial velocity measurements and jointly fitting a circular orbit model, we find an orbital period of 1.977143 ± 3 × 10^(−6) days, a planetary radius of 5.25 ± 0.17 Rꚛ, and a mass of 23.6 ± 3.3 Mꚛ implying a mean density of ρp =0.91 ± 0.15 g/cu. cm. A non-circular orbit model fit delivers similar planetary mass and radius values within the uncertainties. Given the measured planetary radius and mass, TOI-674b is one of the largest and most massive super-Neptune class planets discovered around an M-type star to date. It is found in the Neptunian desert, and is a promising candidate for atmospheric characterization using the James Webb Space Telescope.

F. Murgas↗

NASA NTRS1995

A spectroscopic and photometric study of 12 BM Camelopardalis

Radial velocities from 1916.95 to 1991.95 and photometry from l979.25, both published and new in this paper, are presented and analyzed. A new solution of the radial velocity curve reveals a new period of 80.90 days and an eccentricity of e = 0.05 +/- 0.02, both very different from the 80.17 days and 0.35 found by Abt et al. (1969). An alternative solution with e = 0 is given because we cannot decide firmly whether or not the small eccentricity is real. We find V sin i = 11.3 +/- 0.3 km/s from Maidanak and 10 unequal depth. 0.048 mins and 0.026 mins. The orbital ephemeris for conjunction (K gisnt behind) is JD(hel.) 2,448,111.1 (+/- 0.4 days ) + 80.898 days (+/- 0.004 days ) E, consistent with both the radial velocities and the photometry. With the ellipticity effect removed, the light curve shows residual variability which we fit with a two-spot model. During the 13 years covered by photometry there were nine different starspots, the largest one producing a light loss of 0.19 mins. Rotation periods for the nine spots ranged from 78.6 +/- 0.5 days to 83.7 +/- 0.4 days from which we concluded that the K giant does rotate synchronously but with a differential rotation coefficient of k = 0.06 +/- 0.01. Lifetimes for the nine spots ranged from 1.1 to greater than 4.2 yr and were consistent with the empirical spot lifetime laws of Hall & Henry (1994). Use of the mass function, the orbital period, the V sin i, the two different ellipticity effect amplitudes, and various logical constraints led to ranges of possible masses, radii and inclinations. The most believable solution was around i = 90 deg, R(sub 1) = 24 solar radii, M(sub 1) = 1.1 solar mass, and M(sub 2) = 0.6 solar mass. THe Rossby number for the K giant is 0.48, small enough compared to the critical value of 0.65 to explain why, though rotating 'slowly', it does have large spots.

Hall, Douglas S.↗

DOE OSTI2021

Ion temperature measurements from tomographic reconstruction of Doppler spectra in the presence of multi-component flow in two dimensions

A new ion Doppler diagnostic has been constructed to measure ion temperature profiles in the presence of multi-component flow during magnetic reconnection experiments. The inversion technique and diagnostic setup are applicable to axisymmetric plasmas with two-component flow across the measurement cross section, which occurs during magnetic reconnection. The particular design discussed here is optimized for operation on the Magnetic Reconnection eXperiment (MRX) at Princeton Plasma Physics Laboratory. To prove the viability of this diagnostic for MRX and the future Facility for Laboratory Reconnection Experiments, measurements have been taken and ion temperature and perpendicular flow profiles have been obtained. The radial velocity on MRX does not contribute to the Doppler shift of the measured spectra but does contribute to the broadening of the spectra, while toroidal flow contributes to both. It is shown that neglecting the radial velocity for vR = 20 km/s leads to an error in the ion temperature inversion of 20%. Results from MRX discharges are shown, and the impact of radial velocity on ion temperature inversions is discussed.

Goodman, A. (ORCID:0000000336396572)↗

NASA NTRS1976

Ultraviolet absorption lines associated with the Vela supernova remnant

Two stars behind the Vela supernova remnant and two stars offset from the remnant have been observed with the UV spectrometer aboard the Copernicus satellite. Over 200 interstellar atomic and molecular absorption features between 1000 and 1400 A have been identified and measured for radial velocity and equivalent width. In many cases, additional information was obtained by studying the detailed shapes of the recorded profiles. Most of the stars show several absorption components, with clouds of the highest radial velocity appearing in the spectra of stars behind the remnant. For each component, column densities were derived using velocity dispersion parameters which yielded the most self-consistent results. Qualitatively, the gas toward the remnant exhibits a number of unusual properties, when compared with normal interstellar material. First, abnormally high radial velocities were evident. Second, the degree of ionization of some elements suggested the existence of ionizing processes significantly more potent than those found in general regions of space. Finally, an investigation of electron densities shows that much of the gas, especially that at high velocity, must exist in the form of relatively thin sheets or filaments. If cosmic abundances prevail, the column densities of high-velocity excited material suggest that H-alpha emission measures could be as large as 100 sq cm/cu pc.

Jenkins, E. B.↗

DOE OSTI2020

TOI-824 b: A New Planet on the Lower Edge of the Hot Neptune Desert

We report the detection of a transiting hot Neptune exoplanet orbiting TOI-824 (SCR J1448-5735), a nearby (d = 64 pc) K4V star, using data from the Transiting Exoplanet Survey Satellite. The newly discovered planet has a radius R {sub p} = 2.93 ± 0.20 R{sub ⊕} and an orbital period of 1.393 days. Radial velocity measurements using the Planet Finder Spectrograph and the High Accuracy Radial velocity Planet Searcher spectrograph confirm the existence of the planet, and we estimate its mass to be 18.47 ± 1.84 M{sub ⊕}. The planet’s mean density is ρ{sub p} = 4.03{sub −0.78}{sup +0.98} g cm{sup −3}, making it more than twice as dense as Neptune. TOI-824 b's high equilibrium temperature makes the planet likely to have a cloud-free atmosphere, and thus it is an excellent candidate for follow-up atmospheric studies. The detectability of TOI-824 b’s atmosphere from both ground and space is promising and could lead to the detailed characterization of the most irradiated small planet at the edge of the hot Neptune desert that has retained its atmosphere to date.

79 ASTRONOMY AND ASTROPHYSICS↗

NASA NTRS2003

A Program to Detect and Characterize Extra-Solar Giant Planets

We initiated a significant hardware upgrade to the AFOE, to increase its efficiency for precise radial velocity studies to the level where we can continue to contribute usefully to extrasolar planet research on relatively bright stars. The AFOE, at a 1.5-m telescope, will of course not have the sensitivity of radial velocity instruments at larger telescopes, such as the HIRES on Keck or the Hectochelle on the MMT telescope (about to come on line). However, it has been possible to increase its efficiency for precise radial velocity studies by a factor of 4 to 5, which-combined with the large amount of telescope time available at the 1.5-m telescope-will permit us to do intensive follow-up observations of stars brighter than about 8 magnitude. The AFOE was originally designed primarily for asteroseismology using a ThAr reference. This provided useful wavelength stability over tens of minutes as required for asteroseismology, but we were unable to get a long-term (month-to-month) velocity precision better than about 15 m/s with that setup. Hence, we implemented an iodine cell as a wavelength reference for extrasolar planet studies. However, the optical design of the original AFOE did not completely span the wavelength range covered by the iodine absorption spectrum, and furthermore the optics suffered significant light loss through optical obscuration in the camera secondary. To remedy this, we replaced the AFOE grating with a new one that covered the entire iodine spectral range at somewhat lower spectral resolution, and replaced the camera with a transmitting lens. (The use of a lens was made possible by restricting the spectral range covered by the upgraded AFOE to only the iodine region.) These upgrades were successfully completed, and the instrument was tested for three nights in fall of 2002. The expected improvement in sensitivity by a factor of 4 to 5 was observed: that is, the same velocity precision as previously attained (of order 5 to 7 m/s) was now obtained on a stars that are about 4 to 5 times fainter. Unfortunately, just after installing the new AFOE optics, there was a catastrophic failure of the old Tektronix CCD. A careful investigation was made, and it was determined that the failure was probably due to too many thermal cyclings over the previous 8 years. The only solution was to purchase a new CCD. Internal funds of $16,000 were found for this purpose, and the new CCD (a thinned, back-illuminated Marconi 2K x 2K device with 13.5 micron pixels, and employing dual readout channels to keep the readout time as short as 20 seconds) was ordered, has now arrived, and is currently under test before 1 being installed in the AFOE liquid nitrogen dewar. At the same time, we expect to implement new CCD control electronics. This system should be better in many ways than the previous detector (including eliminating the need for UV flashing to maximize the quantum efficiency). We plan to install the detector on the telescope and begin operations again in April of this year.

Lindstrom, David↗

NASA NTRS1985

Spectroscopic orbits for 16 more binaries in the Hyades field

A photoelectric survey of the radial velocities of Hyades candidates has provided data for 16 spectroscopic binary orbits, in addition to the 11 known binaries in the Hyades field. The majority of photoelectric observations in the survey were carried out at the Cambridge and Palomar Observatories using different data reduction techniques for determining radial velocities. It is found that two of the objects, vB 164 and J336, are definitely not members of the Hyades cluster; two other objects, HD 16909 and J301, appear to be located far from the center of the cluster, but still deserve classification as Hyades members. The gamma-velocity of HD 16909 differed slightly from the value expected for a member of the Hyades cluster. An additional twelve systems were definitely identified as members of the Hyades. The radial velocity values for all the candidate stars are given in a series of tables.

Griffin, R. F.↗

NASA NTRS1980

Pulsation of late B-type stars

Radial velocity observations of three of the brightest stars in the Pleiades, Alcyone, Maia and Taygeta, made during the course of one night, 25 October 1976, are discussed. All three stars were discovered to be pulsating with periods of a few hours. Analysis of all published radial velocities for each star, covering more than 70 years and approximately 100,000 cycles, has established the value of the periods to eight decimal places, and demonstrated constancy of the periods. However, amplitudes of the radial velocity variations change over long time intervals, and changes in spectral line intensities are observed in phase with the pulsation. All three stars may also be members of binary systems.

Beardsley, W. R.↗

NASA NTRS1972

Apollo 15 mission report: Apollo 15 guidance, navigation, and control system performance analysis report (supplement 1)

This report contains the results of additional studies which were conducted to confirm the conclusions of the MSC Mission Report and contains analyses which were not completed in time to meet the mission report deadline. The LM IMU data were examined during the lunar descent and ascent phases. Most of the PGNCS descent absolute velocity error was caused by platform misalignments. PGNCS radial velocity divergence from AGS during the early part of descent was partially caused by PGNCS gravity computation differences from AGS. The remainder of the differences between PGNCS and AGS velocity were easily attributable to attitude reference alignment differences and tolerable instrument errors. For ascent the PGNCS radial velocity error at insertion was examined. The total error of 10.8 ft/sec was well within mission constraints but larger than expected. Of the total error, 2.30 ft/sec was PIPA bias error, which was suspected to exist pre-lunar liftoff. The remaining 8.5 ft/sec is most probably satisified with a large pre-liftoff planform misalignment.

Source record↗

NASA NTRS2000

Limits on Line Bisector Variability for Stars with Extrasolar Planets

We present an analysis of high-resolution synoptic spectra of ten F- and G-type stars, seven of which exhibit periodic radial velocity variations due to the presence of one or more substellar companions. We searched for subtle periodic variations in photospheric line asymmetry, as characterized by line bisectors. In principle, periodic variations in line asymmetry observed at lower spectral resolution could mimic the radial velocity signature of a companion, but we find no significant evidence of such behavior in our data. Observations were obtained from 1998 March to 1999 February using the National Solar Observatory (NSO) 1.52-m McMath-Pierce Solar Telescope Facility on Kitt Peak in conjunction with the solar-stellar spectrograph, achieving a resolving power of 1.2x10(exp5). To characterize line asymmetry, we first measured line bisectors for the unblended Fe I photospheric line at 625.26 nm. To improve sensitivity to small fluctuations, we then combined points in each bisector to form a velocity displacement with respect to the line core. We searched for periodic variations in this displacement, finding no substantial difference between stars with substellar companions and those without reported companions. We find no correlation between bisector velocity displacement and the known orbital phase of substellar companions around our target stars. Simulations of a periodic signal with noise levels that mimic our measurement errors suggest that we can exclude bisector variations with amplitudes greater than about 20 m/s. These results support the conclusion that extrasolar planets best explain the observed periodic variations in radial velocity.

Povich, M. S.↗

NASA NTRS1982

A spectroscopic study of LMC X-4

The orbital radial velocity semi-amplitude of the binary star system LMC X-4 primary was determined to be 37.9 + or - 2.4 km/s from measurements of the hydrogen absorption lines. The semi-amplitude of the He I and He II absorption lines are consistent with this, namely 44.9 + or - 5.0 and 37.3 + or - 5.3 km/s. The phase and shape of the radial velocity curves of the three ions are consistent with a circular orbit and an ephemeris based upon X-ray measurements of the neutron star, with the exception that the He II absorption line radial velocity curve has detectable shape distortion. Measurements of the He II LAMBOA 4686 emission line velocity are consistent with a phase shifted sine wave of semi-amplitude 535 km/s, a square wave of semi-amplitude 407 km/s, or high order harmonic fits. The spectral type was found to be 08.5 IV-V during X-ray eclipse. Variations to types as early as 07 occur, but not as a function or orbital phase. Absorption line peculiarities were noted on 6 of 58 spectra.

Petro, L. D.↗

NASA NTRS1980

Mode identification in Beta Cephei stars

The essential observational characteristics related to mode identification are summarized. Major emphasis is placed on the following: both light and velocity amplitudes; typical periods in both light and radial velocity; the light curve for Beta Cephei stars in comparison to the classical Cepheids and RR Lyrae stars; the van Hoof effect with respect to the radial velocity curves in many Beta Cephei stars; and the line profiles of many Beta Cephei stars.

Aizenmen, M. L.↗

DOE OSTI2021

dlmcfpt.c1

The DLMC VAP uses inertial data from the ARM NAV system to transform the Doppler lidar beam angles (az and el) from the lidar's frame of reference to an Earth-fixed frame such the azimuth angle is measured clockwise from true north and the elevation angle is measured from the local horizon. Additionally, the VAP compensates the observed radial (air) velocity data for the effects of the platform velocity (i.e. corrected_radial_velocity = observed_radial_velocity-platform_radial_velocity). The VAP was developed specifically for MOSAiC. The dlmcfpt.c1 product contains the fixed point, or staring data. The dlmcusr.c1 product contains a user defined scan which is anything the operator wants it to be.

54 ENVIRONMENTAL SCIENCES↗

DOE OSTI2021

dlmcusr.c1

54 ENVIRONMENTAL SCIENCES↗