A. Mainzer

California Institute of Technology, Pasadena, California, United States

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Publications (384)360.87 Total impact

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    ABSTRACT: The Euphrosyne asteroid family is uniquely situated at high inclination in the outer Main Belt, bisected by the nu_6 secular resonance. This large, low albedo family may thus be an important contributor to specific subpopulations of the near-Earth objects. We present simulations of the orbital evolution of Euphrosyne family members from the time of breakup to the present day, focusing on those members that move into near-Earth orbits. We find that family members typically evolve into a specific region of orbital element-space, with semimajor axes near ~3 AU, high inclinations, very large eccentricities, and Tisserand parameters similar to Jupiter family comets. Filtering all known NEOs with our derived orbital element limits, we find that the population of candidate objects is significantly lower in albedo than the overall NEO population, although many of our candidates are also darker than the Euphrosyne family, and may have properties more similar to comet nuclei. Followup characterization of these candidates will enable us to compare them to known family properties, and confirm which ones originated with the breakup of (31) Euphrosyne.
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    Dataset: 1505.01923
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    Seth C. Koren · Edward L. Wright · A. Mainzer
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    ABSTRACT: We report Markov chain Monte Carlo fits of the thermophysical model of Wright (2007) to the fluxes of 10 asteroids which have been observed by both WISE and NEOWISE. This model is especially useful when one has observations of an asteroid at multiple epochs, as it takes advantage of the views of different local times and latitudes to determine the spin axis and the thermal parameter. Many of the asteroids NEOWISE observes will have already been imaged by WISE, so this proof of concept shows there is an opportunity to use a rotating cratered thermophysical model to determine surface thermal properties of a large number of asteroids.
    Icarus 06/2015; 258. DOI:10.1016/j.icarus.2015.06.014 · 2.84 Impact Factor
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    A. Mainzer · F. Usui · D. Trilling
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    ABSTRACT: Large-area surveys operating at mid-infrared wavelengths have proven to be a valuable means of discovering and characterizing minor planets. Through the use of radiometric models, it is possible to derive physical properties such as diameters, albedos, and thermal inertia for large numbers of objects. Modern detector array technology has resulted in a significant improvement in spatial resolution and sensitivity compared with previous generations of space-based infrared telescopes, giving rise to a commensurate increase in the number of objects that have been observed at these wavelengths. Space-based infrared surveys of asteroids therefore offer an effective means of rapidly gathering information about small body populations' orbital and physical properties. The AKARI, WISE/NEOWISE, Spitzer, and Herschel missions have significantly increased the number of minor planets with well-determined diameters and albedos.
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    ABSTRACT: We present thermal model fits for 11 Jovian and 3 Saturnian irregular satellites based on measurements from the WISE/NEOWISE dataset. Our fits confirm spacecraft-measured diameters for the objects with in situ observations (Himalia and Phoebe) and provide diameters and albedo for 12 previously unmeasured objects, 10 Jovian and 2 Saturnian irregular satellites. The best-fit thermal model beaming parameters are comparable to what is observed for other small bodies in the outer Solar System, while the visible, W1, and W2 albedos trace the taxonomic classifications previously established in the literature. Reflectance properties for the irregular satellites measured are similar to the Jovian Trojan and Hilda Populations, implying common origins.
    The Astrophysical Journal 05/2015; 809(1). DOI:10.1088/0004-637X/809/1/3 · 6.28 Impact Factor
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    ABSTRACT: During the "WISE at 5: Legacy and Prospects" conference in Pasadena, CA -- which ran from February 10 - 12, 2015 -- attendees were invited to engage in an interactive session exploring the future uses of the Wide-field Infrared Survey Explorer (WISE) data. The 65 participants -- many of whom are extensive users of the data -- brainstormed the top questions still to be answered by the mission, as well as the complementary current and future datasets and additional processing of WISE/NEOWISE data that would aid in addressing these most important scientific questions. The results were mainly bifurcated between topics related to extragalactic studies (e.g. AGN, QSOs) and substellar mass objects. In summary, participants found that complementing WISE/NEOWISE data with cross-correlated multiwavelength surveys (e.g. SDSS, Pan-STARRS, LSST, Gaia, Euclid, etc.) would be highly beneficial for all future mission goals. Moreover, developing or implementing machine-learning tools to comb through and understand cross-correlated data was often mentioned for future uses. Finally, attendees agreed that additional processing of the data such as co-adding WISE and NEOWISE and extracting a multi-epoch photometric database and parallax and proper motion catalog would greatly improve the scientific results of the most important projects identified. In that respect, a project such as MaxWISE which would execute the most important additional processing and extraction as well as make the data and catalogs easily accessible via a public portal was deemed extremely important.
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    ABSTRACT: We have carried out simulations to predict the performance of a new space-based telescopic survey operating at thermal infrared wavelengths that seeks to discover and characterize a large fraction of the potentially hazardous near-Earth asteroid (NEA) population. Two potential architectures for the survey were considered: one located at the Earth-Sun L1 Lagrange point, and one in a Venus-trailing orbit. A sample cadence was formulated and tested, allowing for the self-follow-up necessary for objects discovered in the daytime sky on Earth. Synthetic populations of NEAs with sizes >=140 m in effective spherical diameter were simulated using recent determinations of their physical and orbital properties. Estimates of the instrumental sensitivity, integration times, and slew speeds were included for both architectures assuming the properties of new large-format 10 um detector arrays capable of operating at ~35 K. Our simulation included the creation of a preliminary version of a moving object processing pipeline suitable for operating on the trial cadence. We tested this pipeline on a simulated sky populated with astrophysical sources such as stars and galaxies extrapolated from Spitzer and WISE data, the catalog of known minor planets (including Main Belt asteroids, comets, Jovian Trojans, etc.), and the synthetic NEA model. Trial orbits were computed for simulated position-time pairs extracted from the synthetic surveys to verify that the tested cadence would result in orbits suitable for recovering objects at a later time. Our results indicate that the Earth-Sun L1 and Venus-trailing surveys achieve similar levels of integral completeness for potentially hazardous asteroids larger than 140 m; placing the telescope in an interior orbit does not yield an improvement in discovery rates. This work serves as a necessary first step for the detailed planning of a next-generation NEA survey.
    The Astronomical Journal 01/2015; 149(5). DOI:10.1088/0004-6256/149/5/172 · 4.05 Impact Factor
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    R. Stevenson · J. M. Bauer · R. M. Cutri · A . K. Mainzer · F. J. Masci
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    ABSTRACT: The Near-Earth Object Wide-field Infrared Survey Explorer (NEOWISE) mission observed comet C/2013 A1 (Siding Spring) three times at 3.4 {\mu}m and 4.6 {\mu}m as the comet approached Mars in 2014. The comet is an extremely interesting target since its close approach to Mars in late 2014 will be observed by various spacecraft in-situ. The observations were taken in 2014 Jan., Jul. and Sep. when the comet was at heliocentric distances of 3.82 AU, 1.88 AU, and 1.48 AU. The level of activity increased significantly between the Jan. and Jul. visits but then decreased by the time of the observations in Sep., approximately 4 weeks prior to its close approach to Mars. In this work we calculate Af\r{ho} values, and CO/CO2 production rates.
    12/2014; 798(2). DOI:10.1088/2041-8205/798/2/L31
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    S. Sonnett · A. Mainzer · T. Grav · J. Masiero · J. Bauer
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    ABSTRACT: Determining the binary fraction for a population of asteroids, particularly as a function of separation between the two components, helps describe the dynamical environment at the time the binaries formed, which in turn offers constraints on the dynamical evolution of the solar system. We searched the NEOWISE archival dataset for close and contact binary Trojans and Hildas via their diagnostically large lightcurve amplitudes. We present 48 out of 554 Hilda and 34 out of 953 Trojan binary candidates in need of follow-up to confirm their large lightcurve amplitudes and subsequently constrain the binary orbit and component sizes. From these candidates, we calculate a preliminary estimate of the binary fraction without confirmation or debiasing of 14-23% for Trojans larger than ~12 km and 30-51% for Hildas larger than ~4 km. Once the binary candidates have been confirmed, it should be possible to infer the underlying, debiased binary fraction through estimation of survey biases.
    The Astrophysical Journal 12/2014; 799(2). DOI:10.1088/0004-637X/799/2/191 · 6.28 Impact Factor
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    ABSTRACT: M.P.E.C. 2014-U19 Issued 2014 Oct. 18, 16:53 UT The Minor Planet Electronic Circulars contain information on unusual minor planets and routine data on comets. They are published on behalf of Commission 20 of the International Astronomical Union by the Minor Planet Center, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A. Prepared using the Tamkin Foundation Computer Network MPC@CFA.HARVARD.EDU URL http://www.minorplanetcenter.net/ ISSN 1523-6714 2014 TJ64 Observations: K14T64J* S2014 10 07.79182 19 23 38.99 -42 45 15.1 19 RLEU019C51 K14T64J s2014 10 07.79182 1 + 2357.7810 - 4504.7416 - 4647.1640 EU019C51 K14T64J S2014 10 08.05490 19 24 33.00 -42 54 34.2 LEU019C51 K14T64J s2014 10 08.05490 1 + 2382.2213 - 4510.3105 - 4629.2512 EU019C51 K14T64J S2014 10 08.18644 19 25 00.22 -42 59 12.4 LEU019C51 K14T64J s2014 10 08.18644 1 + 2394.4827 - 4513.0890 - 4620.2011 EU019C51 K14T64J S2014 10 08.25215 19 25 13.92 -43 01 32.1 LEU019C51 K14T64J s2014 10 08.25215 1 + 2394.0625 - 4486.5994 - 4646.1564 EU019C51 K14T64J S2014 10 08.31785 19 25 27.58 -43 03 51.0 LEU019C51 K14T64J s2014 10 08.31785 1 + 2393.5302 - 4460.0324 - 4671.9549 EU019C51 K14T64J S2014 10 08.38369 19 25 41.37 -43 06 11.4 LEU019C51 K14T64J s2014 10 08.38369 1 + 2406.3317 - 4489.4520 - 4637.0462 EU019C51 K14T64J S2014 10 08.44939 19 25 55.09 -43 08 29.9 LEU019C51 K14T64J s2014 10 08.44939 1 + 2405.7815 - 4462.9712 - 4662.8387 EU019C51 K14T64J S2014 10 08.51510 19 26 08.93 -43 10 46.9 LEU019C51 K14T64J s2014 10 08.51510 1 + 2405.2429 - 4437.0219 - 4687.8918 EU019C51 K14T64J S2014 10 08.51523 19 26 08.95 -43 10 48.7 LEU019C51 K14T64J s2014 10 08.51523 1 + 2418.7633 - 4492.9528 - 4627.2370 EU019C51 K14T64J S2014 10 08.58093 19 26 22.79 -43 13 07.6 LEU019C51 K14T64J s2014 10 08.58093 1 + 2418.1939 - 4466.5447 - 4653.0456 EU019C51 K14T64J S2014 10 09.04113 19 28 00.60 -43 29 18.0 19 RLEU019C51 K14T64J s2014 10 09.04113 1 + 2440.3301 - 4393.1426 - 4711.0297 EU019C51 K14T64J S2014 10 09.04126 19 28 00.63 -43 29 18.8 LEU019C51 K14T64J s2014 10 09.04126 1 + 2454.5058 - 4449.2184 - 4650.6169 EU019C51 K14T64J S2014 10 09.17267 19 28 28.94 -43 33 54.1 LEU019C51 K14T64J s2014 10 09.17267 1 + 2452.6597 - 4396.3640 - 4701.6038 EU019C51 K14T64J S2014 10 09.30421 19 28 57.35 -43 38 31.3 LEU019C51 K14T64J s2014 10 09.30421 1 + 2465.0183 - 4399.5763 - 4692.1172 EU019C51 K14T64J S2014 10 09.43575 19 29 25.95 -43 43 06.9 LEU019C51 K14T64J s2014 10 09.43575 1 + 2477.4211 - 4402.8375 - 4682.5064 EU019C51 K14T64J S2014 10 09.56716 19 29 54.60 -43 47 41.6 LEU019C51 K14T64J s2014 10 09.56716 1 + 2475.0313 - 4349.9127 - 4732.9884 EU019C51 K14T64J KC2014 10 09.84701019 30 55.10 -43 57 25.8 21.5 RqEU019K93 K14T64J KC2014 10 09.85424619 30 56.65 -43 57 40.3 21.4 RqEU019K93 K14T64J KC2014 10 09.86329919 30 58.57 -43 57 58.8 22.2 RqEU019K93 K14T64J 4C2014 10 10.98527 19 35 13.60 -44 36 54.4 cEU019I11 K14T64J 4C2014 10 10.98611 19 35 13.84 -44 36 56.8 21.5 RcEU019I11 K14T64J 4C2014 10 10.98693 19 35 13.98 -44 36 58.1 21.5 RcEU019I11 K14T64J 4C2014 10 10.98775 19 35 14.14 -44 36 59.9 21.5 RcEU019I11 K14T64J KC2014 10 11.11134119 35 41.62 -44 41 09.2 20.5 RtEU019W86 K14T64J KC2014 10 11.12092119 35 43.79 -44 41 28.0 21.7 RtEU019W86 K14T64J KC2014 10 11.13056719 35 45.99 -44 41 47.2 21.0 RtEU019W86 K14T64J KC2014 10 18.10543420 06 31.93 -48 28 44.6 21.3 RtEU019W86 K14T64J KC2014 10 18.11068220 06 33.45 -48 28 53.7 21.1 RtEU019W86 K14T64J KC2014 10 18.11593020 06 34.97 -48 29 03.0 21.2 RtEU019W86 Observer details: C51 WISE. Measurers A. K. Mainzer, J. M. Bauer, T. Grav, J. R. Masiero, J. W. Dailey, R. M. Cutri, E. L. Wright, C. Nugent, S. Sonnett, R. Stevenson. I11 Gemini South Observatory, Cerro Pachon. Observers J. Masiero, A. Cardwell, E. Wenderoth. Measurer J. Masiero. 8.0-m reflector. K93 Sutherland-LCOGT C. Observer T. Lister. 1.0-m f/8 Ritchey-Chretien + CCD. W86 Cerro Tololo-LCOGT B. Observer T. Lister. 1.0-m f/8 Ritchey-Chretien + CCD. Orbital elements: 2014 TJ64 Earth MOID = 0.1537 AU Epoch 2014 Dec. 9.0 TT = JDT 2457000.5 MPC M 9.36589 (2000.0) P Q n 0.23291111 Peri. 235.12847 +0.92748200 -0.34229560 a 2.6162299 Node 144.20439 +0.36711645 +0.90991332 e 0.5975137 Incl. 14.89729 -0.07072939 +0.23428930 P 4.23 H 21.2 G 0.15 U 6 Residuals in seconds of arc 141007 C51 0.2+ 0.3- 141009 C51 0.2- 0.2- 141010 I11 0.6+ 0.6- 141008 C51 0.2- 0.4- 141009 C51 0.2- 0.5- 141010 I11 0.2+ 0.3- 141008 C51 0.3- 0.4+ 141009 C51 0.2+ 0.3+ 141010 I11 0.0 0.4- 141008 C51 0.2+ 0.1- 141009 C51 0.1- 0.5- 141011 W86 0.2- 0.4- 141008 C51 0.1- 0.0 141009 C51 0.1+ 0.1- 141011 W86 0.1- 0.1- 141008 C51 0.3+ 0.8- 141009 C51 0.4- 0.3+ 141011 W86 0.0 0.2- 141008 C51 0.1- 0.4- 141009 K93 0.1- 0.7+ 141018 W86 0.1+ 0.1+ 141008 C51 0.4+ 1.4+ 141009 K93 0.1- 0.9+ 141018 W86 0.0 0.1+ 141008 C51 0.2+ 0.2+ 141009 K93 0.5- 0.7+ 141018 W86 0.1- 0.0 141008 C51 0.4+ 0.0 141010 I11 0.0 0.0 Ephemeris: 2014 TJ64 a,e,i = 2.62, 0.60, 15 q = 1.0530 Date TT R. A. (2000) Decl. Delta r Elong. Phase V 2014 09 18 18 39 04.2 -30 39 01 0.4262 1.1799 103.5 55.9 21.7 ... 2014 10 03 19 08 48.6 -39 52 45 0.4100 1.1079 94.0 64.3 21.8 ... 2014 10 11 19 35 17.1 -44 37 18 0.4013 1.0806 90.7 67.5 21.8 ... 2014 10 17 20 01 09.2 -47 54 43 0.3949 1.0659 89.0 69.2 21.8 2014 10 18 20 06 01.8 -48 25 30 0.3939 1.0640 88.8 69.4 21.7 2014 10 19 20 11 04.5 -48 55 31 0.3929 1.0622 88.6 69.7 21.7 ... 2014 10 25 20 45 03.9 -51 36 10 0.3872 1.0548 88.0 70.4 21.7 ... 2014 11 02 21 40 11.9 -53 57 14 0.3814 1.0538 88.5 70.3 21.7 ... 2014 11 17 23 39 50.3 -52 37 17 0.3798 1.0789 93.2 66.2 21.6 A. U. Tomatic (C) Copyright 2014 MPC M.P.E.C. 2014-U19
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    ABSTRACT: We present 20 WISE-selected galaxies with bolometric luminosities L_bol > 10^14 L_sun, including five with infrared luminosities L_IR = L(rest 8-1000 micron) > 10^14 L_sun. These "extremely luminous infrared galaxies," or ELIRGs, were discovered using the "W1W2-dropout" selection criteria (Eisenhardt et al. 2012) which requires marginal or non-detections at 3.4 and 4.6 micron (W1 and W2, respectively) but strong detections at 12 and 22 micron in the WISE survey. Their spectral energy distributions are dominated by emission at rest-frame 4-10 micron, suggesting that hot dust with T_d ~ 450K is responsible for the high luminosities. These galaxies are likely powered by highly obscured AGNs, and there is no evidence suggesting these systems are beamed or lensed. We compare this WISE-selected sample with 116 optically selected quasars that reach the same L_bol level, corresponding to the most luminous unobscured quasars in the literature. We find that the rest-frame 5.8 and 7.8 micron luminosities of the WISE-selected ELIRGs can be 30%-80% higher than that of the unobscured quasars. Assuming Eddington-limited accretion, the existence of AGNs with L_bol > 10^14 L_sun at z > 3 places strong constraints on the supermassive black hole growth history, suggesting that these supermassive black holes are born with large mass, or have very rapid mass assembly, possibly by chaotic accretion.
    The Astrophysical Journal 10/2014; 805(2). DOI:10.1088/0004-637X/805/2/90 · 6.28 Impact Factor
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    ABSTRACT: This work reports high quality NIR spectra, and their respective interpretations, for eight Vp type asteroids, as defined by Carvano et al. (2010), that were observed at the NASA Infrared Telescope Facility on January 14, 2013 UT. They include (3867) Shiretoko, (5235) Jean-Loup, (5560) Amytis, (6331) 1992 FZ1, (6976) Kanatsu, (17469) 1991 BT, (29796) 1999 CW77, and (30872) 1992 EM17. All eight asteroids exhibit the broad 0.9 and 1.9 micron mineral absorption features indicative of pyroxene on each asteroid's surface. Data reduction and analysis via multiple techniques produced consistent results for the derived spectral absorption band centers and average pyroxene surface chemistries for all eight asteroids (Reddy et al., 2012; Lindsay et al., 2013,2014; Gaffey et al., 2002; Burbine et al., 2009). (3867) Shiretoko is most consistent with the eucrite meteorites while the remaining seven asteroids are most consistent with the howardite meteorites. The existing evidence suggests that all eight of these Vp type asteroids are genetic Vestoids that probably originated from Vesta's surface.
    Icarus 08/2014; 242. DOI:10.1016/j.icarus.2014.08.020 · 2.84 Impact Factor
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    ABSTRACT: Mid-infrared spectral observations Uranus acquired with the Infrared Spectrometer (IRS) on the Spitzer Space Telescope are used to determine the abundances of C2H2, C2H6, CH3C2H, C4H2, CO2, and tentatively CH3 on Uranus at the time of the 2007 equinox. For vertically uniform eddy diffusion coefficients in the range 2200-2600 cm2 s-1, photochemical models that reproduce the observed methane emission also predict C2H6 profiles that compare well with emission in the 11.6-12.5 micron wavelength region, where the nu9 band of C2H6 is prominent. Our nominal model with a uniform eddy diffusion coefficient Kzz = 2430 cm2 sec-1 and a CH4 tropopause mole fraction of 1.6x10-5 provides a good fit to other hydrocarbon emission features, such as those of C2H2 and C4H2, but the model profile for CH3C2H must be scaled by a factor of 0.43, suggesting that improvements are needed in the chemical reaction mechanism for C3Hx species. The nominal model is consistent with a CH3D/CH4 ratio of 3.0+-0.2x10-4. From the best-fit scaling of these photochemical-model profiles, we derive column abundances above the 10-mbar level of 4.5+01.1/-0.8 x 10+19 molecule-cm-2 for CH4, 6.2 +- 1.0 x 10+16 molecule-cm-2 for C2H2 (with a value 24% higher from a different longitudinal sampling), 3.1 +- 0.3 x 10+16 molecule-cm-2 for C2H6, 8.6 +- 2.6 x 10+13 molecule-cm-2 for CH3C2H, 1.8 +- 0.3 x 10+13 molecule-cm-2 for C4H2, and 1.7 +- 0.4 x 10+13 molecule-cm-2 for CO2 on Uranus. Our results have implications with respect to the influx rate of exogenic oxygen species and the production rate of stratospheric hazes on Uranus, as well as the C4H2 vapor pressure over C4H2 ice at low temperatures.
    Icarus 07/2014; 243. DOI:10.1016/j.icarus.2014.07.012 · 2.84 Impact Factor
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    ABSTRACT: On 2007 December 16-17, spectra were acquired of the disk of Uranus by the Spitzer Infrared Spectrometer (IRS) when its equator was close to the sub-earth point. This spectrum provides the highest-resolution broad-band spectrum ever obtained for Uranus from space, allowing a determination of the disk-averaged temperature and molecule composition to a greater degree of accuracy than ever before. The temperature profiles derived from the Voyager radio occultation experiments that match these data best are those that assume a high abundance of methane in the deep atmosphere, but none of these models provides a satisfactory fit over the full spectral range. This be the result of spatial differences between global and low-latitudinal regions, changes in time, missing continuum opacity sources such as stratospheric hazes or unknown tropospheric constituents, or undiagnosed systematic problems with either the radio-occultation or the Spitzer IRS data sets. The spectrum is compatible with the stratospheric temperatures derived from the Voyager ultraviolet occultations measurements. Thermospheric temperatures determined from the analysis of the observed H2 quadrupole emission features are colder than those derived by Herbert et al. at pressures less than ~1 microbar. Extrapolation of the nominal model spectrum to far-infrared through millimeter wavelengths shows that the spectrum arising solely from H2 collision-induced absorption is too warm to reproduce observations between wavelengths of 0.8 and 3.3 mm. Adding an additional absorber such as H2S provides a reasonable match to the spectrum, although a unique identification of the responsible absorber is not yet possible with available data. An immediate practical use for the spectrum resulting from this model is to establish a high-precision continuum flux model for use as an absolute radiometric standard for future astronomical observations.
    Icarus 07/2014; 243. DOI:10.1016/j.icarus.2014.07.010 · 2.84 Impact Factor
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    ABSTRACT: We present revised near-infrared albedo fits of 2835 Main Belt asteroids observed by WISE/NEOWISE over the course of its fully cryogenic survey in 2010. These fits are derived from reflected-light near-infrared images taken simultaneously with thermal emission measurements, allowing for more accurate measurements of the near-infrared albedos than is possible for visible albedo measurements. As our sample requires reflected light measurements, it undersamples small, low albedo asteroids, as well as those with blue spectral slopes across the wavelengths investigated. We find that the Main Belt separates into three distinct groups of 6%, 16%, and 40% reflectance at 3.4 um. Conversely, the 4.6 um albedo distribution spans the full range of possible values with no clear grouping. Asteroid families show a narrow distribution of 3.4 um albedos within each family that map to one of the three observed groupings, with the (221) Eos family being the sole family associated with the 16% reflectance 3.4 um albedo group. We show that near-infrared albedos derived from simultaneous thermal emission and reflected light measurements are an important indicator of asteroid taxonomy and can identify interesting targets for spectroscopic followup.
    The Astrophysical Journal 06/2014; 791(2). DOI:10.1088/0004-637X/791/2/121 · 6.28 Impact Factor
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    ABSTRACT: NASA's Wide-field Infrared Survey Explorer (WISE) spacecraft has been brought out of hibernation and has resumed surveying the sky at 3.4 and 4.6 um. The scientific objectives of the NEOWISE reactivation mission are to detect, track, and characterize near-Earth asteroids and comets. The search for minor planets resumed on December 23, 2013, and the first new near-Earth object (NEO) was discovered six days later. As an infrared survey, NEOWISE detects asteroids based on their thermal emission and is equally sensitive to high and low albedo objects; consequently, NEOWISE-discovered NEOs tend to be large and dark. Over the course of its three-year mission, NEOWISE will determine radiometrically-derived diameters and albedos for approximately 2000 NEOs and tens of thousands of Main Belt asteroids. The 32 months of hibernation have had no significant effect on the mission's performance. Image quality, sensitivity, photometric and astrometric accuracy, completeness, and the rate of minor planet detections are all essentially unchanged from the prime mission's post-cryogenic phase.
    The Astrophysical Journal 06/2014; 792(1). DOI:10.1088/0004-637X/792/1/30 · 6.28 Impact Factor
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    ABSTRACT: The Wide-field Infrared Survey Explorer (WISE) spacecraft has been reactivated as NEOWISE-R to characterize and search for Near Earth Objects. The brown dwarf WISE J085510.83-071442.5 has now been reobserved by NEOWISE-R, and we confirm the results of Luhman (2014b), who found a very low effective temperature, a very high proper motion, and a large parallax. The large proper motion has separated the brown dwarf from the background sources that influenced the 2010 WISE data, allowing a measurement of a very red WISE color of W1-W2 > 3.9. A re-analysis of the 2010 WISE astrometry using only the W2 band, combined with the new NEOWISE-R 2014 position, gives an improved parallax of 448 +/- 32 mas and proper motion of 8.072 +/- 0.026 arcsec/yr. These are all consistent with Luhman (2014b).
    The Astronomical Journal 05/2014; 148(5). DOI:10.1088/0004-6256/148/5/82 · 4.05 Impact Factor
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    ABSTRACT: Comet 17P/Holmes underwent a massive outburst in 2007 October, brightening by a factor of almost a million in under 48 hr. We used infrared images taken by the Wide-Field Infrared Survey Explorer mission to characterize the comet as it appeared at a heliocentric distance of 5.1 AU almost 3 yr after the outburst. The comet appeared to be active with a coma and dust trail along the orbital plane. We constrained the diameter, albedo, and beaming parameter of the nucleus to 4.135 ± 0.610 km, 0.03 ± 0.01, and 1.03 ± 0.21, respectively. The properties of the nucleus are consistent with those of other Jupiter family comets. The best-fit temperature of the coma was 134 ± 11 K, slightly higher than the blackbody temperature at that heliocentric distance. Using Finson-Probstein modeling, we found that the morphology of the trail was consistent with ejection during the 2007 outburst and was made up of dust grains between 250 μm and a few cm in radius. The trail mass was ~1.2-5.3 × 1010 kg.
    The Astrophysical Journal 05/2014; 787(2):116. DOI:10.1088/0004-637X/787/2/116 · 6.28 Impact Factor

Publication Stats

2k Citations
360.87 Total Impact Points

Institutions

  • 2006–2014
    • California Institute of Technology
      • Jet Propulsion Laboratory
      Pasadena, California, United States
    • The University of Arizona
      • Department of Astronomy
      Tucson, Arizona, United States
  • 2008
    • University of California, Los Angeles
      • Department of Physics and Astronomy
      Los Angeles, CA, United States