Search NASA⌕ Search

SEARCH · Search NASA

Results for “PROPER MOTION”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 271 records · Page 15
All sourcesNASA NTRSDOE OSTI
NASA NTRS2014

A High-Resolution X-Ray and Optical Study of SN1006: Asymmetric Expansion and Small-Scale Structure in a Type Ia Supernova Remnant

We introduce a deep (670 ks) X-ray survey of the entire SN 1006 remnant from the Chandra X-Ray Observatory, together with a deep Hα image of SN 1006 from the 4 m Blanco telescope at CTIO. Comparison with Chandra images from 2003 gives the first measurement of the X-ray proper motions around the entire periphery, carried out over a 9 yr baseline. We find that the expansion velocity varies significantly with azimuth. The highest velocity of approx.7400 km/s (almost 2.5 times that in the northwest (NW)) is found along the southeast (SE) periphery, where both the kinematics and the spectra indicate that most of the X-ray emission stems from ejecta that have been decelerated little, if at all. Asymmetries in the distribution of ejecta are seen on a variety of spatial scales. Si-rich ejecta are especially prominent in the SE quadrant, while O and Mg are more uniformly distributed, indicating large-scale asymmetries arising from the explosion itself. Neon emission is strongest in a sharp filament just behind the primary shock along the NWrim, where the pre-shock density is highest. Here the Ne is likely interstellar, while Ne within the shell may include a contribution from ejecta. Within the interior of the projected shell we find a few isolated "bullets" of what appear to be supernova ejecta that are immediately preceded by bowshocks seen in Hα, features that we interpret as ejecta knots that have reached relatively dense regions of the surrounding interstellar medium, but that appear in the interior in projection. Recent three-dimensional hydrodynamic models for Type Ia supernovae display small-scale features that strongly resemble the ones seen in X-rays in SN 1006; an origin in the explosion itself or from subsequent hydrodynamic instabilities both remain viable options. We have expanded the search for precursor X-ray emission ahead of a synchrotron-dominated shock front, as expected from diffusive shock acceleration theory, to numerous regions along both the northeast and southwest rims of the shell. Our data require that a precursor be thinner than about 3, and fainter than about 5% of the post-shock peak. These limits suggest that the magnetic field is amplified by a factor of seven or more in a narrow precursor region, promoting diffusive particle acceleration.

galaxies: active↗
NASA NTRS2014

Relating Jet Structure to Photometric Variability: the Herbig Ae Star HD 163296

Herbig Ae/Be stars are intermediate-mass pre-main sequence stars surrounded by circumstellar dust disks. Some are observed to produce jets, whose appearance as a sequence of shock fronts (knots) suggests a past episodic outflow variability. This "jet fossil record" can be used to reconstruct the outflow history. We present the first optical to near-infrared (NIR) spectra of the jet from the Herbig Ae star HD 163296, obtained with VLT/X-shooter. We determine the physical conditions in the knots and also their kinematic "launch epochs". Knots are formed simultaneously on either side of the disk, with a regular interval of ∼16 yr. The velocity dispersion versus jet velocity and the energy input are comparable between both lobes. However, the mass-loss rate, velocity, and shock conditions are asymmetric. We find ˙M(jet)/ ˙M(acc) is approximately 0.01−0.1, which is consistent with magneto-centrifugal jet launching models. No evidence of any dust is found in the high-velocity jet, suggesting a launch region within the sublimation radius (greater than 0.5 au). The jet inclination measured from proper motions and radial velocities confirms that it is perpendicular to the disk. A tentative relation is found between the structure of the jet and the photometric variability of the central source. Episodes of NIR brightening were previously detected and attributed to a dusty disk wind. We report for the first time significant optical fadings lasting from a few days up to a year, coinciding with the NIR brightenings. These are very likely caused by dust lifted high above the disk plane, and this supports the disk wind scenario. The disk wind is launched at a larger radius than the high-velocity atomic jet, although their outflow variability may have a common origin. No significant relation between outflow and accretion variability could be established. Our findings confirm that this source undergoes periodic ejection events, which may be coupled with dust ejections above the disk plane.

kinematic launch epochs↗
NASA NTRS2012

A Celestial Reference Frame at X/ka-Band (8.4/32 Ghz) for Deep Space Navigation

Deep space tracking and navigation are done in a quasi-inertial reference frame based upon the angular positions of distant active galactic nuclei (AGN). These objects, which are found at extreme distances characterized by median redshifts of z = 1, are ideal for reference frame definition because they exhibit no measurable parallax or proper motion. They are thought to be powered by super massive black holes whose gravitational energy drives galactic sized relativistic jets. These jets produce synchrotron emissions which are detectable by modern radio techniques such as Very Long baseline Interferometry (VLBI).

very long baseline interferometry (VLBI)↗
NASA NTRS2016

Ogle-2012-blg-0724lb: A Saturn Mass Planet Around an M-dwarf

We report the discovery of a planet by the microlensing method, OGLE-2012-BLG-0724Lb. Although the duration of the planetary signal for this event was one of the shortest seen for a planetary event, the anomaly was well covered thanks to high-cadence observations taken by the survey groups OGLE and MOA. By analyzing the light curve, this planetary system is found to have a mass ratio q = (1.58 +/- 0.15) x 10(exp -3). By conducting a Bayesian analysis, we estimate that the host star is an M dwarf with a mass of M(sub L) = 0.29(+0.33/-0.16) solar mass located at D(sub L) = 6.7(+1.1/-1.2) kpc away from the Earth and the companion's mass is m(sub P) = 0.47(+0.54/-0.26) M(Jup). The projected planet- host separation is a falsum = 1.6(+0.4/-0.3) AU. Because the lens-source relative proper motion is relatively high, future highresolution images would detect the lens host star and determine the lens properties uniquely. This system is likely a Saturn-mass exoplanet around an M dwarf, and such systems are commonly detected by gravitational microlensing. This adds another example of a possible pileup of sub-Jupiters (0.2 less than m(sub P)/M(sub Jup) less than 1) in contrast to a lack of Jupiters (approximately 1-2 M(sub Jup)) around M dwarfs, supporting the prediction by core accretion models that Jupiter-mass or more massive planets are unlikely to form around M dwarfs.

microlensing↗
NASA NTRS2017

The First Brown Dwarf Discovered by the Backyard Worlds: Planet 9 Citizen Science Project

The Wide-field Infrared Survey Explorer (WISE) is a powerful tool for finding nearby brown dwarfs and searching for new planets in the outer solar system, especially with the incorporation of NEOWISE and NEOWISE Reactivation data. However, so far, searches for brown dwarfs in WISE data have yet to take advantage of the full depth of the WISE images. To efficiently search this unexplored space via visual inspection, we have launched anew citizen science project, called "Backyard Worlds: Planet 9," which asks volunteers to examine short animations composed of difference images constructed from time-resolved WISE co adds. We report the first new substellar object discovered by this project, WISEA J110125.95+540052.8, a T5.5 brown dwarf located approximately 34 pc from the Sun with a total proper motion of approx.0. "7/ yr. WISEA J110125.95+540052.8 has a WISE W2 magnitude of W2 = 15.37+/- 0.09; our sensitivity to this source demonstrates the ability of citizen scientists to identify moving objects via visual inspection that are 0.9 mag fainter than the W2 single-exposure sensitivity, a threshold that has limited prior motion-based brown dwarf searches with WISE.

Wide-field Infrared Survey Explorer (WISE)↗
NASA NTRS2013

Direct Imaging Discovery of A Super-Jupiter Around the Late B-Type Star K And*

We present the direct imaging discovery of an extrasolar planet, or possible low-mass brown dwarf, at a projected separation of 55 plus or minus 2 AU (1."058 plus or minus 0."007) from the B9-type star K And. The planet was detected with Subaru/HiCIAO (Subaru/High Contrast Instrument for the Subaru Next Generation Adaptive Optics) during the SEEDS (Strategic Exploration of Exoplanets and Disks with Subaru Telescope/HiCIAO) survey and confirmed as a bound companion via common proper motion measurements. Observed near-infrared magnitudes of J equals 16.3 plus or minus 0.3, H equals 15.2 plus or minus 0.2, K (sub s) = 14.6 plus or minus 0.4, and L prime equals 13.12 plus or minus 0.09 indicate a temperature of approximately 1700 degrees Kelvin. The galactic kinematics of the host star are consistent with membership in the Columba Association, implying a corresponding age of 30 (exp from plus 20 to minus10) Myr. The systems age, combined with the companion photometry, points to a model-dependent companion mass approximately 12.8 times the mass of Jupiter. The host stars estimated mass of 2.4 to 2.5 times the mass of the sun places it among the most massive stars ever known to harbor an extrasolar planet or low-mass brown dwarf. While the mass of the companion is close to the deuterium burning limit, its mass ratio, orbital separation, and likely planet-like formation scenario imply that it may be best defined as a super-Jupiter with properties similar to other recently discovered companions to massive stars.

HiCIAO↗
NASA NTRS2018

The Expansion of the Young Supernova Remnant 0509-68.7 (N103B)

We present a second epoch of Chandra observations of the Type Ia Large Magellanic Cloud supernova remnant(SNR) 0509-68.7 (N103B) obtained in 2017. When combined with the earlier observations from 1999, we have a17.4 year baseline with which we can search for evidence of the remnant's expansion. Although the lack of strongpoint source detections makes absolute image alignment at the necessary accuracy impossible, we can measure thechange in the diameter and the area of the remnant, and find that it has expanded by an average velocity of 4170(2860, 5450) km s1. This supports the picture of this being a young remnant; this expansion velocity correspondsto an undecelerated age of 850 years, making the real age somewhat younger, consistent with results from lightecho studies. Previous infrared observations have revealed high densities in the western half of the remnant, likelyfrom circumstellar material, so it is probable that the real expansion velocity is lower on that side of the remnantand higher on the eastern side. A similar scenario is seen in Kepler's SNR. N103B joins the rare class ofMagellanic Cloud SNRs with measured proper motions.

Williams, Brian J.↗
NASA NTRS2019

OGLE-2018-BLG-0022: First Prediction of an Astrometric Microlensing Signal from a Photometric Microlensing Event

In this work, we present the analysis of the binary microlensing event OGLE-2018-BLG-0022 that is detected toward the Galactic bulge field. The dense and continuous coverage with the high-quality photometry data from ground-based observations combined with the space-based Spitzer observations of this long timescale event enables us to uniquely determine the masses M1=0.40 ± 0.05Me and M2=0.13 ± 0.01Me of the individual lens components. Because the lens-source relative parallax and the vector lens-source relative proper motion are unambiguously determined, we can likewise unambiguously predict the astrometric offset between the light centroid of the magnified images (as observed by the Gaia satellite) and the true position of the source. This prediction can be tested when the individual-epoch Gaia astrometric measurements are released.

Han, Cheongho↗
NASA NTRS2020

On the changes in the physical properties of the ionized region around the Weigelt structures in n Carinae over the 5.54-yr spectroscopic cycle

We present HST/STIS observations and analysis of two prominent nebular structures around the central source of η Carinae, the knots C and D. The former is brighter than the latter for emission lines from intermediate or high ionization potential ions. The brightness of lines from intermediate and high ionization potential ions significantly decreases at phases around periastron. We do not see conspicuous changes in the brightness of lines from low ionization potential (<13.6 eV) ions over the orbital period. Line ratios suggest that the total extinction towards the Weigelt structures is AV=2.0. Weigelt C and D are characterized by an electron density o f10(exp 6.9)/cu.cm that does not significantly change throughout the orbital cycle. The electron temperature varies from 5500K (around periastron) to 7200K (around apastron). The relative changes in the brightness of He I lines are well reproduced by the variations in the electron temperature alone. We found that, at phases around periastron, the electron temperature seems to be higher for Weigelt C than that of D. The Weigelt structures are located close to the Homunculus equatorial plane, at a distance of about 1240 AU from the central source. From the analysis of proper motion and age, the Weigelt complex can be associated with the equatorial structure called ‘Butterfly Nebula’ surrounding the central binary system.

M. Teodoro↗
NASA NTRS2020

Candidate Brown-dwarf Microlensing Events with Very Short Timescales and Small Angular Einstein Radii

Short-timescale microlensing events are likely to be produced by substellar brown dwarfs (BDs), but it is difficult to securely identify BD lenses based on only event timescales because short-timescale events can also be produced by stellar lenses with high relative lens-source proper motions. In this paper, we report three strong candidate BD-lens events found from the search for lensing events not only with short timescales (t(E) ≲ 6 days) but also with very small angular Einstein radii (θ(E) ≲ 0.05 mas) among the events that have been found in the 2016–2019 observing seasons. These events include MOA-2017-BLG-147, MOA-2017-BLG-241, and MOA-2019-BLG-256, in which the first two events are produced by single lenses and the last event is produced by a binary lens. From the Monte Carlo simulations of Galactic events conducted with the combined t(E) and θ(E) constraint, it is estimated that the lens masses of the individual events are 0.051 (sup +0.100, sub -0.027) M(ʘ), 0.044 (sup +0.090, sub -0.023) M(ʘ), and 0.046 (sup +0.067, sub -0.023) M(ʘ)/0.038 (sup +0.056, sub -0.019) M(ʘ) and the probability of the lens mass smaller than the lower limit of stars is ~80% for all events. We point out that routine lens mass measurements of short-timescale lensing events require survey-mode space-based observations.

Cheongho Han↗
NASA NTRS2019

MOA-bin-29b: A Microlensing Gas-giant Planet Orbiting a Low-mass Host Star

We report the discovery of a gas-giant planet orbiting a low-mass host star in the microlensing event MOA-bin-29 that occurred in 2006. We find five degenerate solutions with the planet/host-star mass ratio of q ∼ 10(exp−2). The Einstein radius crossing time of all models are relatively short (∼4–7 days), which indicates that the mass of host star is likely low. The measured lens-source proper motion is 5–9 mas/yr depending on the models. Since only finite source effects are detected, we conduct a Bayesian analysis in order to obtain the posterior probability distribution of the lens physical properties. As a result, we find the lens system is likely to be a gas-giant orbiting a brown dwarf or a very late M-dwarf in the Galactic bulge. The probability distributions of the physical parameters for the five degenerate models are consistent within the range of error. By combining these probability distributions, we conclude that the lens system is a gas giant with a mass of M(p)= 0.63(sub +1.13, sub 0.39) M(Jup) orbiting a brown dwarf with a mass of M(h)= 0.06 (sup +0.11, sub -0.04) M(ʘ) at a projected star–planet separation of r⊥ = 0.53(sup +0.89, sub -0.18)au . The lens distance is D(L)= 6.89(sup +1.19, sub -1.19) kpc, i.e., likely within the Galactic bulge.

Iona Kondo↗
NASA NTRS2019

The 2L1S/1L2S Degeneracy for Two Microlensing Planet Candidates Discovered by the KMTNet Survey in 2017

We report two microlensing planet candidates discovered by the Korea Microlensing Telescope Network (KMTNet) survey in 2017. However, both events have the 2L1S/1L2S degeneracy, which is an obstacle to claiming the discovery of the planets with certainty unless the degeneracy can be resolved. For KMT-2017-BLG-0962, the degeneracy cannot be resolved. If the 2L1S solution is correct, KMT-2017-BLG-0962 might be produced by a super Jupiter-mass planet orbiting a mid-M-dwarf host star. For KMT-2017-BLG-1119, the light-curve modeling favors the 2L1S solution but higher-resolution observations of the baseline object tend to support the 1L2S interpretation rather than the planetary interpretation. This degeneracy might be resolved by a future measurement of the lens-source relative proper motion. This study shows that the problem of resolving 2L1S/1L2S degeneracy exists over a much wider range of conditions than those considered by the theoretical study of Gaudi (1998).

I.-G. Shin↗
NASA NTRS2019

Spitzer Parallax of OGLE-2018-BLG-0596: A Low-mass-ratio Planet around an M Dwarf

We report the discovery of a Spitzer microlensing planet OGLE-2018-BLG-0596Lb, with preferred planet-host mass ratio q ~ 2 × 10(exp −4). The planetary signal, which is characterized by a short (~1 day) "bump" on the rising side of the lensing light curve, was densely covered by ground-based surveys. We find that the signal can be explained by a bright source that fully envelops the planetary caustic, i.e., a "Hollywood" geometry. Combined with the source proper motion measured from Gaia, the Spitzer satellite parallax measurement makes it possible to precisely constrain the lens physical parameters. The preferred solution, in which the planet perturbs the minor image due to lensing by the host, yields a Uranus-mass planet with a mass of M(p) = 13.9 ± 1.6 M(⊕) orbiting a mid M-dwarf with a mass of M(h) = 0.23 ± 0.03 M(⊙). There is also a second possible solution that is substantially disfavored but cannot be ruled out, for which the planet perturbs the major image. The latter solution yields M(p) = 1.2 ± 0.2 M(⊕) and M(h) = 0.15 ± 0.02 M(⊙). By combining the microlensing and Gaia data together with a Galactic model, we find in either case that the lens lies on the near side of the Galactic bulge at a distance D(L) ~ 6 ± 1 kpc. Future adaptive optics observations may decisively resolve the major image/minor image degeneracy.

Youn Kil Jung↗
NASA NTRS2019

OGLE-2018-BLG-0022: First Prediction of an Astrometric Microlensing Signal from a Photometric Microlensing Event

In this work, we present the analysis of the binary microlensing event OGLE-2018-BLG-0022 that is detected toward the Galactic bulge field. The dense and continuous coverage with the high-quality photometry data from ground-based observations combined with the space-based Spitzer observations of this long timescale event enables us to uniquely determine the masses M 1 = 0.40 ± 0.05 M ⊙ and M 2 = 0.13 ± 0.01 M ⊙ of the individual lens components. Because the lens-source relative parallax and the vector lens-source relative proper motion are unambiguously determined, we can likewise unambiguously predict the astrometric offset between the light centroid of the magnified images (as observed by the Gaia satellite) and the true position of the source. This prediction can be tested when the individual-epoch Gaia astrometric measurements are released.

Cheongho Han↗
NASA NTRS2020

Bayesian Approach for Determining Microlens System Properties with High-angular resolution Follow-up Imaging

We present the details of the Bayesian analysis of the planetary microlensing event MOA-2016-BLG-227, whose excess flux is likely due to a source/lens companion or an unrelated ambient star, as well as of the assumed prior distributions. Furthermore, we apply this method to four reported planetary events, MOA-2008-BLG-310, MOA2011-BLG-293, OGLE-2012-BLG-0527, and OGLE-2012-BLG-0950, where adaptive optics observations have detected excess flux at the source star positions. For events with small angular Einstein radii, our lens mass estimates are more uncertain than those of previous analyses, which assumed that the excess was due to the lens. Our predictions for MOA-2008-BLG-310 and OGLE-2012-BLG-0950 are consistent with recent results on these events obtained via Keck and Hubble Space Telescope observations when the source star is resolvable from the lens star. For events with small angular Einstein radii, we find that it is generally difficult to conclude whether the excess flux comes from the host star. Therefore, it is necessary to identify the lens star by measuring its proper motion relative to the source star to determine whether the excess flux comes from the lens star. Even without such measurements, our method can be used to statistically test the dependence of the planet-hosting probability on the stellar mass.

Naoki Koshimoto↗
NASA NTRS2020

Confirmation of the Stellar Binary Microlensing Event, Macho 97-BLG-28

The high-magnification microlensing event MACHO-97-BLG-28 was previously determined to be a binary system composed of either two M dwarfs or an M dwarf and a brown dwarf. We present a revised light-curve model using additional data from the Mt. Stromlo 74″telescope, model estimates of stellar limb darkening, and fitting of the blend separately for each telescope and passband. We find a lensing system with a larger mass ratio, q=0.28±0.01, and smaller projected separation, s=0.61±0.01, than those presented in the original study. We revise the estimate of the lens–source relative proper motion to μ(rel)=2.8±0.5 mas/yr, which indicates that 16.07 yr after the event maximum the lens and source should have separated by 46±8 mas. We revise the radius of the source star using more recent reddening maps and angular diameter–color relations to R(*)=(10.3±1.9) R(ʘ). K- and J-band adaptive optics images of the field taken at this epoch using the NIRC2 imager on the Keck telescope show that the source and lens are still blended, consistent with our light-curve model. With no statistically significant excess flux detection we constrain the mass, M(L)=0.24 (+0.28, -0.12) M(ʘ), and distance, D(L)=7.0±1.0 kpc, of the lensing system. This supports the interpretation of this event as a stellar binary in the Galactic bulge. This lens mass gives a companion mass of M= 0.07(+0.08,-0.04) M(ʘ), close to the boundary between being a star and a brown dwarf.

W. Blackman↗
NASA NTRS2020

Keck Observations Confirm a Super-Jupiter Planet Orbiting M Dwarf OGLE-2005 BLG-071L

We present adaptive optics imaging from the NIRC2 instrument on the Keck II telescope that resolves the exoplanet host (and lens) star as it separates from the brighter source star. These observations yield the K-band brightness of the lens and planetary host star, as well as the lens-source relative proper motion, μ(rel,H), in the heliocentric reference frame. The μ(rel,H) measurement allows for the determination of the microlensing parallax vector, π(E), which had only a single component determined by the microlensing light curve. The combined measurements of μ(rel,H) and K(L) provide the masses of the host star, M(host) = 0.426 ± 0.037M(ʘ), and planet, m(p)=3.27±0.32M(Jupiter) with a projected separation of 3.4±0.5 au. This confirms the tentative conclusion of a previous paper that this super-Jupiter mass planet, OGLE-2005-BLG-071Lb, orbits an M dwarf. Such planets are predicted to be rare by the core accretion theory and have been difficult to find with other methods, but there are two such planets with firm mass measurements from microlensing, and an additional 11 planetary microlens events with host mass estimates <0.5M(ʘ) and planet mass estimates >2 Jupiter masses that could be confirmed by high angular follow-up observations. We also point out that OGLE-2005-BLG-071L has separated far enough from its host star that it should be possible to measure the host-star metallicity with spectra from a high angular resolution telescope such as Keck, the Very Large Telescope, the Hubble Space Telescope, or the James Webb Space Telescope.

David P Bennett↗
NASA NTRS2004

White light modeling, algorithm development, and validation on the micro-arcsecond metrology testbed

The Space Interferometry Mission (SIM), scheduled for launch in early 2010, is an optical interferometer that will perform narrow angle and global wide angle astrometry with unprecedented accuracy, providing differential position accuracies of 1uas, and 4uas global accuracies in position, proper motion and parallax. SIM astrometric measurements are synthesized from pathlength delay measurements provided by three Michelson-type, white light interferometers. Two of the interferometers are used for making precise measurements of variations in the spacecraft attitude, while the third interferometer performs the science measurement. The ultimate performance of SIM relies on a combination of precise fringe measurements of the interfered starlight with picometer class relative distance measurements made between a set of fiducials that define the interferometer baseline vectors. The focus of the present paper is on the development and analysis of algorithms for accurate white light fringe estimation, and on the preliminary validation of these algorithms on the Micro-Arcsecond Testbed (MAM).

Shen, Janice TsaePyng↗