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Caltech Authors (155.447 recursos)

Repository of works by Caltech published authors.

Group = Infrared Processing and Analysis Center (IPAC)

Mostrando recursos 1 - 20 de 712

  1. The Solar Neighborhood. XXXX. Parallax Results from the CTIOPI 0.9 m Program: New Young Stars Near the Sun

    Bartlett, Jennifer L.; Lurie, John C.; Riedel, Adric; Ianna, Philip A.; Jao, Wei-Chun; Henry, Todd J.; Winters, Jennifer G.; Finch, Charlie T.; Subasavage, John P.
    As a step toward completing and characterizing the census of the solar neighborhood, we present astrometric, photometric, and spectroscopic observations of 32 systems observed with the Cerro Tololo Inter-American Observatory 0.9 m and 1.5 m telescopes. Astrometry from the 0.9 m indicates that among the 17 systems that had no previous published trigonometric parallaxes, 14 are within 25 pc. In the full sample, nine systems have proper motions larger than 0.”5 yr^(−1), including 2MASS J02511490-0352459, which exceeds 2.”0 yr^(−1). VRI photometry from the 0.9 m and optical spectra from the 1.5 m indicate that the targets have V = 11–22...

  2. Gemini Observations of Galaxies in Rich Early Environments (GOGREEN) I: survey description

    Balogh, Michael L.; Rettura, Alessandro; Wetzel, Andrew
    We describe a new Large Program in progress on the Gemini North and South telescopes: Gemini Observations of Galaxies in Rich Early Environments (GOGREEN). This is an imaging and deep spectroscopic survey of 21 galaxy systems at 1 < z < 1.5, selected to span a factor >10 in halo mass. The scientific objectives include measuring the role of environment in the evolution of low-mass galaxies, and measuring the dynamics and stellar contents of their host haloes. The targets are selected from the SpARCS, SPT, COSMOS, and SXDS surveys, to be the evolutionary counterparts of today's clusters and groups. The...

  3. Asteroid spin-rate studies using large sky-field surveys

    Chang, Chan-Kao; Lin, Hsing-Wen; Ip, Wing-Huen; Prince, Thomas A.; Kulkarni, Shrinivas R.; Levitan, David; Laher, Russ; Surace, Jason
    Eight campaigns to survey asteroid rotation periods have been carried out using the intermediate Palomar Transient Factory in the past 3 years. 2780 reliable rotation periods were obtained, from which we identified two new super-fast rotators (SFRs), (335433) 2005 UW163 and (40511) 1999 RE88, and 23 candidate SFRs. Along with other three known super-fast rotators, there are five known SFRs so far. Contrary to the case of rubble-pile asteroids (i.e., bounded aggregations by gravity only), an internal cohesion, ranging from 100 to 1000 Pa, is required to prevent these five SFRs from flying apart because of their super-fast rotations. This...

  4. A Panchromatic View of Brown Dwarf Aurorae

    Pineda, J. Sebastian; Hallinan, Gregg; Kao, Melodie M.
    Stellar coronal activity has been shown to persist into the low-mass star regime, down to late M-dwarf spectral types. However, there is now an accumulation of evidence suggesting that at the end of the main sequence, there is a transition in the nature of the magnetic activity from chromospheric and coronal to planet-like and auroral, from local impulsive heating via flares and MHD wave dissipation to energy dissipation from strong large-scale magnetospheric current systems. We examine this transition and the prevalence of auroral activity in brown dwarfs through a compilation of multiwavelength surveys of magnetic activity, including radio, X-ray, and...

  5. Project 1640 observations of the white dwarf HD 114174 B

    Bacchus, E.; Beichman, C.; Dekany, R.; Hillenbrand, L.; Nilsson, R.
    We present the first near infrared spectrum of the faint white dwarf companion HD 114174 B, obtained with Project 1640. Our spectrum, covering the Y, J and H bands, combined with previous TaRgetting bENchmark-objects with Doppler Spectroscopy (TRENDS) photometry measurements, allows us to place further constraints on this companion. We suggest two possible scenarios; either this object is an old, low-mass, cool H atmosphere white dwarf with T_(eff) ∼ 3800 K or a high-mass white dwarf with T_(eff) > 6000 K, potentially with an associated cool (T_(eff) ∼ 700 K) brown dwarf or debris disc resulting in an infrared excess...

  6. Mid-infrared Variability of Changing-look AGNs

    Sheng, Zhenfeng; Wang, Tinggui; Jiang, Ning; Yang, Chenwei; Yan, Lin; Dou, Liming; Peng, Bo
    It is known that some active galactic nuclei (AGNs) transit from Type 1 to Type 2 or vice versa. There are two explanations for the so-called changing-look AGNs: one is the dramatic change of the obscuration along the line of sight, and the other is the variation of accretion rate. In this Letter, we report the detection of large amplitude variations in the mid-infrared luminosity during the transitions in 10 changing-look AGNs using the Wide-field Infrared Survey Explorer (WISE) and newly released Near-Earth Object WISE Reactivation data. The mid-infrared light curves of 10 objects echo the variability in the optical...

  7. A Herschel/PACS Far-infrared Line Emission Survey of Local Luminous Infrared Galaxies

    Díaz-Santos, T.; Armus, L.; Charmandaris, V.; Lu, N; Stierwalt, S.; Stacey, G.; Malhotra, S.; van der Werf, P. P.; Howell, J. H.; Privon, G. C.; Mazzarella, J. M.; Goldsmith, P. F.; Murphy, E. J.; Barcos-Muñoz, L.; Linden, S. T.; Inami, H.; Larson, K. L.; Evans, A. S.; Appleton, P.; Iwasawa, K.; Lord, S.; Sanders, D. B.; Surace, J. A.
    We present an analysis of, [O I]_(63) [O III]_(88), [N II]_(122), and [C II]_(158) far-infrared (FIR) fine-structure line observations obtained with Herschel/PACS, for ~240 local luminous infrared galaxies (LIRGs) in the Great Observatories All-sky LIRG Survey. We find pronounced declines ("deficits") of line-to-FIR continuum emission for [N II]_(122) , [O I]_(63) and [C II]_(158) as a function of FIR color and infrared luminosity surface density, Σ_(IR). The median electron density of the ionized gas in LIRGs, based on the [N II]_(122)/[N II]_(205) ratio, is n_e = 41 cm^(−3). We find that the dispersion in the [C II]_(158) deficit of LIRGs...

  8. Red but not dead: unveiling the star-forming far-infrared spectral energy distribution of SpARCS brightest cluster galaxies at 0 < z < 1.8

    Bonaventura, N. R.; Webb, T. M. A.; Muzzin, A.; Noble, A.; Lidman, C.; Wilson, G.; Yee, H. K. C.; Geach, J.; Hezaveh, Y.; Shupe, D.; Surace, J.
    We present the results of a Spitzer/Herschel infrared photometric analysis of the largest (716) and the highest-redshift (z = 1.8) sample of brightest cluster galaxies (BCGs), those from the Spitzer Adaptation of the Red-Sequence Cluster Survey Given the tension that exists between model predictions and recent observations of BCGs at z < 2, we aim to uncover the dominant physical mechanism(s) guiding the stellar mass buildup of this special class of galaxies, the most massive in the Universe and uniquely residing at the centres of galaxy clusters. Through a comparison of their stacked, broad-band, infrared spectral energy distributions (SEDs) to...

  9. The California-Kepler Survey. II. Precise Physical Properties of 2025 Kepler Planets and Their Host Stars

    Johnson, John Asher; Petigura, Erik A.; Fulton, Benjamin J.; Marcy, Geoffrey W.; Howard, Andrew W.; Isaacson, Howard; Hebb, Leslie; Cargile, Phillip A.; Morton, Timothy D.; Weiss, Lauren M.; Winn, Joshua N.; Rogers, Leslie A.; Sinukoff, Evan; Hirsch, Lea A.
    We present stellar and planetary properties for 1305 Kepler Objects of Interest (KOIs) hosting 2025 planet candidates observed as part of the California-Kepler Survey. We combine spectroscopic constraints, presented in Paper I, with stellar interior modeling to estimate stellar masses, radii, and ages. Stellar radii are typically constrained to 11%, compared to 40% when only photometric constraints are used. Stellar masses are constrained to 4%, and ages are constrained to 30%. We verify the integrity of the stellar parameters through comparisons with asteroseismic studies and Gaia parallaxes. We also recompute planetary radii for 2025 planet candidates. Because knowledge of planetary...

  10. Ground-based Parallax Confirmed by Spitzer: Binary Microlensing Event MOA-2015-BLG-020

    Wang, Tianshu; Beichman, C.; Calchi Novati, S.; Carey, S.
    We present the analysis of the binary gravitational microlensing event MOA-2015-BLG-020. The event has a fairly long timescale (~63 days) and thus the light curve deviates significantly from the lensing model that is based on the rectilinear lens-source relative motion. This enables us to measure the microlensing parallax through the annual parallax effect. The microlensing parallax parameters constrained by the ground-based data are confirmed by the Spitzer observations through the satellite parallax method. By additionally measuring the angular Einstein radius from the analysis of the resolved caustic crossing, the physical parameters of the lens are determined. It is found that...

  11. The Origins of [C II] Emission in Local Star-forming Galaxies

    Croxall, K. V.; Smith, J. D.; Pellegrini, E.; Groves, B.; Bolatto, A.; Herrera-Camus, R.; Sandstrom, K. M.; Draine, B.; Wolfire, M. G.; Armus, L.; Boquien, M.; Brandl, B.; Dale, D.; Galametz, M.; Hunt, L.; Kennicutt, R.; Kreckel, K.; Rigopoulou, D.; van der Werf, P.; Wilson, C.
    The [C II] 158 μm fine-structure line is the brightest emission line observed in local star-forming galaxies. As a major coolant of the gas-phase interstellar medium, [C II] balances the heating, including that due to far-ultraviolet photons, which heat the gas via the photoelectric effect. However, the origin of [C II] emission remains unclear because C+ can be found in multiple phases of the interstellar medium. Here we measure the fractions of [C II] emission originating in the ionized and neutral gas phases of a sample of nearby galaxies. We use the [N II] 205 μm fine-structure line to trace...

  12. Dust Properties of C II Detected z ∼ 5.5 Galaxies: New HST/WFC3 Near-IR Observations

    Barisic, I.; Faisst, A. L.; Capak, P. L.; Pavesi, R.; Riechers, D. A.; Scoville, N. Z.; Cooke, K.; Kartaltepe, J. S.; Casey, C. M.; Smolčić, V.
    We examine the rest-frame ultraviolet (UV) properties of 10 [C II]λ158 μm-detected galaxies at z ~ 5.5 in COSMOS using new Hubble Space Telescope/Wide Field Camera 3 near-infrared imaging. Together with pre-existing 158 μm continuum and [C II] line measurements by the Atacama Large Millimeter/submillimeter Array, we study their dust attenuation properties on the IRX–β diagram, which connects the total dust emission (∝ IRX = log(L_(FIR)/L_(1600)) to the line-of-sight dust column (∝ β). We find systematically bluer UV continuum spectral slopes (β) compared to previous low-resolution ground-based measurements, which relieves some of the tension between models of dust attenuation and...

  13. The 24 Micron Source Counts in Deep Spitzer Space Telescope Surveys

    Papovich, C.; Dole, H.; Egami, E.; Le Floc’h, E.; Pérez‐González, P. G.; Alonso‐Herrero, A.; Bai, L.; Beichman, C. A.; Blaylock, M.; Engelbracht, C. W.; Gordon, K. D.; Hines, D. C.; Misselt, K. A.; Morrison, J. E.; Mould, J.; Muzerolle, J.; Neugebauer, G.; Richards, P. L.; Rieke, G. H.; Rieke, M. J.; Rigby, J. R.; Su, K. Y. L.; Young, E. T.
    Galaxy source counts in the infrared provide strong constraints on the evolution of the bolometric energy output from distant galaxy populations. We present the results from deep 24 μm imaging from Spitzer surveys, which include ≈5 × 10^4 sources to an 80% completeness of ≃ 60 μJy. The 24 μm counts rapidly rise at near-Euclidean rates down to 5 mJy, increase with a super-Euclidean rate between 0.4 and 4 mJy, and converge below ~0.3 mJy. The 24 μm counts exceed expectations from nonevolving models by a factor of ≳10 at S_ν ~ 0.1 mJy. The peak in the differential number...

  14. Initial Results from the Palomar Adaptive Optics Survey of Young Solar‐Type Stars: A Brown Dwarf and Three Stellar Companions

    Metchev, Stanimir A.; Hillenbrand, Lynne A.
    We present first results from the Palomar Adaptive Optics Survey of Young Stars conducted at the Hale 5 m telescope. Through direct imaging we have discovered a brown dwarf and two low-mass stellar companions to the young solar-type stars HD 49197, HD 129333 (EK Dra), and V522 Per and confirmed a previously suspected companion to RX J0329.1+0118 (Sterzik et al.), at respective separations of 0."95 (43 AU), 0."74 (25 AU), 2."09 (400 AU), and 3."78 (380 AU). Physical association of each binary system is established through common proper motion and/or low-resolution infrared spectroscopy. Based on the companion spectral types, we...

  15. Ten Micron Observations of Nearby Young Stars

    Metchev, Stanimir A.; Hillenbrand, Lynne A.; Meyer, Michael R.
    We present new 10 μm photometry of 21 nearby young stars obtained at the Palomar 5 m and at the Keck I 10 m telescopes as part of a program to search for dust in the habitable zone of young stars. Thirteen of the stars are in the F-K spectral type range ("solar analogs"), four have B or A spectral types, and four have spectral type M. We confirm existing IRAS 12 μm and ground-based 10 μm photometry for 10 of the stars and present new insight into this spectral regime for the rest. Excess emission at 10 μm is...

  16. Adaptive Optics Observations of Vega: Eight Detected Sources and Upper Limits to Planetary‐Mass Companions

    Metchev, Stanimir A.; Hillenbrand, Lynne A.; White, Russel J.
    From adaptive optics observations with the Palomar 5 m telescope we place upper limits on the masses of any planetary companions located between ~30 and 230 AU away from Vega, where our data are sensitive to depths ranging from H = 12.5-19.0 mag fainter than Vega itself. Our observations cover a plus-shaped area with two 25″ × 57″ elements, excluding 7″ × 7″ centered on the star. We have identified two double and four single point sources. These projected companions are 14.9-18.9 mag fainter than Vega and, if physically associated, would have masses ranging from 4 to 35 M_J and...

  17. Adaptive Optics Imaging of the AU Microscopii Circumstellar Disk: Evidence for Dynamical Evolution

    Metchev, Stanimir A.; Eisner, Joshua A.; Hillenbrand, Lynne A.; Wolf, Sebastian
    We present an H-band image of the light scattered from circumstellar dust around the nearby (10 pc) young M star AU Microscopii (AU Mic, GJ 803, HD 197481), obtained with the Keck adaptive optics system. We resolve the disk both vertically and radially, tracing it over 17-60 AU from the star. Our high angular resolution (0.04 or 0.4 AU per resolution element) observations thus offer the opportunity to probe the morphology of the AU Mic debris disk on solar system scales. We identify substructures (dust clumps and gaps) in the disk that may point to the existence of orbiting planets....

  18. Forecasting the Impact of Stellar Activity on Transiting Exoplanet Spectra

    Zellem, Robert T.; Swain, Mark R.; Roudier, Gael; Shkolnik, Evgenya L.; Creech-Eakman, Michelle J.; Ciardi, David R.; Line, Michael R.; Iyer, Aishwarya R.; Bryden, Geoffrey; Llama, Joe; Fahy, Kristen A.
    Exoplanet host star activity, in the form of unocculted starspots or faculae, alters the observed transmission and emission spectra of the exoplanet. This effect can be exacerbated when combining data from different epochs if the stellar photosphere varies between observations due to activity. Here, we present a method to characterize and correct for relative changes due to stellar activity by exploiting multi-epoch (⩾2 visits/transits) observations to place them in a consistent reference frame. Using measurements from portions of the planet's orbit where negligible planet transmission or emission can be assumed, we determine changes to the stellar spectral amplitude. With the...

  19. The Formation and Evolution of Planetary Systems (FEPS): Discovery of an Unusual Debris System Associated with HD 12039

    Hines, Dean C.; Backman, Dana E.; Bouwman, Jeroen; Hillenbrand, Lynne A.; Carpenter, John M.; Meyer, Michael R.; Kim, Jinyoung Serena; Silverstone, Murray D.; Rodmann, Jens; Wolf, Sebastian; Mamajek, Eric E.; Brooke, Timothy Y.; Padgett, Deborah L.; Henning, Thomas; Moro‐Martin, Amaya; Stobie, E. B.; Gordon, Karl D.; Morrison, J. E.; Muzerolle, J.; Su, K. Y. L.
    We report the discovery of a debris system associated with the ~30 Myr old G3/5V star HD 12039 using Spitzer Space Telescope observations from 3.6-160 μm. An observed infrared excess (L_(IR)/L^* = 1 × 10^(-4)) above the expected photosphere for λ ≳ 14 μm is fit by thermally emitting material with a color temperature of T ~ 110 K, warmer than the majority of debris disks identified to date around Sun-like stars. The object is not detected at 70 μm with a 3 σ upper limit 6 times the expected photospheric flux. The spectrum of the infrared excess can be...

  20. The SAMI Galaxy Survey: Mass as the Driver of the Kinematic Morphology–Density Relation in Clusters

    Brough, Sarah; Medling, Anne M.
    We examine the kinematic morphology of early-type galaxies (ETGs) in eight galaxy clusters in the Sydney-AAO Multi-object Integral-field spectrograph Galaxy Survey. The clusters cover a mass range of 14.2 < log(M_(200)/M_☉) < 15.2 and we measure spatially resolved stellar kinematics for 315 member galaxies with stellar masses 10.0

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