135 results on '"Zodiacal light"'
Search Results
2. Zodiacal Exoplanets in Time (ZEIT). XIV. He i Transit Spectroscopy of the 650 Myr Hyades Planet K2-136c
- Author
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Teruyuki Hirano, E. Gaidos, Masayuki Kuzuhara, Motohide Tamura, Tomoyuki Kudo, Masashi Omiya, Hiroki Harakawa, and Takayuki Kotani
- Subjects
Physics ,Zodiacal light ,Planet ,myr ,Astronomy ,General Medicine ,Transit (astronomy) ,Spectroscopy ,Exoplanet - Published
- 2021
3. Collisional Evolution of the Inner Zodiacal Cloud
- Author
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L. C. Gasque, Petr Pokorný, Nathan A. Schwadron, Peter Strub, A. Pusack, J. R. Szalay, Keith Goetz, K. Battams, D. J. McComas, Stuart D. Bale, David M. Malaspina, and Harald Krüger
- Subjects
Physics ,Geophysics ,Interplanetary dust cloud ,Zodiacal light ,Meteoroid ,Space and Planetary Science ,business.industry ,Earth and Planetary Sciences (miscellaneous) ,Astronomy ,Circumstellar dust ,Astronomy and Astrophysics ,Cloud computing ,business - Abstract
The zodiacal cloud is one of the largest structures in the solar system and strongly governed by meteoroid collisions near the Sun. Collisional erosion occurs throughout the zodiacal cloud, yet it is historically difficult to directly measure and has never been observed for discrete meteoroid streams. After six orbits with Parker Solar Probe (PSP), its dust impact rates are consistent with at least three distinct populations: bound zodiacal dust grains on elliptic orbits (α-meteoroids), unbound β-meteoroids on hyperbolic orbits, and a third population of impactors that may be either direct observations of discrete meteoroid streams or their collisional by-products (“β-streams”). The β-stream from the Geminids meteoroid stream is a favorable candidate for the third impactor population. β-streams of varying intensities are expected to be produced by all meteoroid streams, particularly in the inner solar system, and are a universal phenomenon in all exozodiacal disks. We find the majority of collisional erosion of the zodiacal cloud occurs in the range of 10–20 solar radii and expect this region to also produce the majority of pickup ions due to dust in the inner solar system. A zodiacal erosion rate of at least ∼100 kg s−1 and flux of β-meteoroids at 1 au of (0.4–0.8) × 10−4 m−2 s−1 are found to be consistent with the observed impact rates. The β-meteoroids investigated here are not found to be primarily responsible for the inner source of pickup ions, suggesting nanograins susceptible to electromagnetic forces with radii below ∼50 nm are the inner source of pickup ions. We expect the peak deposited energy flux to PSP due to dust to increase in subsequent orbits, up to 7 times that experienced during its sixth orbit.
- Published
- 2021
4. Optical Night Sky Brightness Measurements from the Stratosphere
- Author
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Ajay Gill, Aurelien A. Fraisse, Paul C. Clark, Jason Rhodes, Jürgen Schmoll, Eric Huff, Sut Ieng Tam, D. Lagattuta, Mohamed M. Shaaban, Suresh Sivanandam, Lun Li, Tim Eifler, C. Barth Netterfield, L. Javier Romualdez, Steven J. Benton, Christopher J. Damaren, Johanna Nagy, James Mullaney, Thuy Vy T. Luu, Anthony M. Brown, Susan Redmond, Jacqueline McCleary, Bradley Holder, Ellen Sirks, M. Galloway, Mathilde Jauzac, J. Hartley, Richard Massey, W. C. Jones, and Jason S.-Y. Leung
- Subjects
Physics ,Brightness ,Zodiacal light ,010504 meteorology & atmospheric sciences ,Gegenschein ,Night sky ,Airglow ,FOS: Physical sciences ,Astronomy ,Astronomy and Astrophysics ,01 natural sciences ,Photometry (optics) ,13. Climate action ,Space and Planetary Science ,Sky brightness ,0103 physical sciences ,Astrophysics - Instrumentation and Methods for Astrophysics ,Instrumentation and Methods for Astrophysics (astro-ph.IM) ,010303 astronomy & astrophysics ,Stratosphere ,0105 earth and related environmental sciences - Abstract
This paper presents optical night sky brightness measurements from the stratosphere using CCD images taken with the Super-pressure Balloon-borne Imaging Telescope (SuperBIT). The data used for estimating the backgrounds were obtained during three commissioning flights in 2016, 2018, and 2019 at altitudes ranging from 28 km to 34 km above sea level. For a valid comparison of the brightness measurements from the stratosphere with measurements from mountain-top ground-based observatories (taken at zenith on the darkest moonless night at high Galactic and high ecliptic latitudes), the stratospheric brightness levels were zodiacal light and diffuse Galactic light subtracted, and the airglow brightness was projected to zenith. The stratospheric brightness was measured around 5.5 hours, 3 hours, and 2 hours before the local sunrise time in 2016, 2018, and 2019 respectively. The $B$, $V$, $R$, and $I$ brightness levels in 2016 were 2.7, 1.0, 1.1, and 0.6 mag arcsec$^{-2}$ darker than the darkest ground-based measurements. The $B$, $V$, and $R$ brightness levels in 2018 were 1.3, 1.0, and 1.3 mag arcsec$^{-2}$ darker than the darkest ground-based measurements. The $U$ and $I$ brightness levels in 2019 were 0.1 mag arcsec$^{-2}$ brighter than the darkest ground-based measurements, whereas the $B$ and $V$ brightness levels were 0.8 and 0.6 mag arcsec$^{-2}$ darker than the darkest ground-based measurements. The lower sky brightness levels, stable photometry, and lower atmospheric absorption make stratospheric observations from a balloon-borne platform a unique tool for astronomy. We plan to continue this work in a future mid-latitude long duration balloon flight with SuperBIT., Comment: 17 pages, 7 figures. Accepted for publication in the Astronomical Journal
- Published
- 2020
5. An Empirical Model of Energetic Neutral Atom Imaging of the Heliosphere and Its Implications for Future Heliospheric Missions at Great Heliocentric Distances
- Author
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Yoshifumi Futaana, Stas Barabash, Peter Wurz, André Galli, and Horst Fichtner
- Subjects
010504 meteorology & atmospheric sciences ,530 Physics ,FOS: Physical sciences ,01 natural sciences ,Interplanetary dust cloud ,Physics - Space Physics ,0103 physical sciences ,Instrumentation and Methods for Astrophysics (astro-ph.IM) ,010303 astronomy & astrophysics ,Solar and Stellar Astrophysics (astro-ph.SR) ,0105 earth and related environmental sciences ,Physics ,Infrared astronomy ,Earth's orbit ,Zodiacal light ,Energetic neutral atom ,520 Astronomy ,Astronomy ,Astronomy and Astrophysics ,620 Engineering ,Space Physics (physics.space-ph) ,Interstellar medium ,Astrophysics - Solar and Stellar Astrophysics ,Space and Planetary Science ,Astrophysics - Instrumentation and Methods for Astrophysics ,Interstellar probe ,Heliosphere - Abstract
Several concepts for heliospheric missions operating at heliocentric distances far beyond Earth orbit are currently investigated by the scientific community. The mission concept of the Interstellar Probe (McNutt et al. 2018), e.g., aims at reaching a distance of 1000 au away from the Sun within this century. This would allow the coming generation to obtain a global view of our heliosphere from an outside vantage point by measuring the Energetic Neutral Atoms (ENAs) originating from the various plasma regions. It would also allow for direct sampling of unperturbed interstellar medium, and for many observation opportunities beyond heliospheric science, such as visits to Kuiper Belt Objects, a comprehensive view on the interplanetary dust populations, and infrared astronomy free from the foreground emission of the Zodiacal cloud. In this study, we present a simple empirical model of ENAs from the heliosphere and derive basic requirements for ENA instrumentation onboard a spacecraft at great heliocentric distances. We consider the full energy range of heliospheric ENAs from 10 eV to 100 keV because each part of the energy spectrum has its own merits for heliospheric science. To cover the full ENA energy range, two or three different ENA instruments are needed. Thanks to parallax observations, some insights about the nature of the IBEX Ribbon and the dimensions of the heliosphere can already be gained by ENA imaging from a few au heliocentric distance. To directly reveal the global shape of the heliosphere, measurements from outside the heliosphere are, of course, the best option., Comment: Paper accepted for publication in The Astrophysical Journal
- Published
- 2019
6. Astrophotos from Our Readers.
- Subjects
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PHOTOGRAPHS , *PICTURES , *COMETS , *LUNAR craters , *NEBULAE , *ZODIACAL light , *ASTRONOMY - Abstract
The section presents several photographs of astronomical images, including photographs of the Fragments B and C of the Comet 73P/Schwassmann-Wachmann 3, craters of the lunar south polar region, the Gum Nebula, the zodiacal light, the night-to-night motion of Venus and the IC 4592 nebula.
- Published
- 2006
7. New Spectral Evidence of an Unaccounted Component of the Near-infrared Extragalactic Background Light from the CIBER
- Author
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Bock, James J., Cooray, Asantha, Korngut, Phillip M., Kim, Min Gyu, Lee, Hyung Mok, Lee, Dae Hee, Levenson, Louis R., Zemcov, Michael, Matsuura, Shuji, Arai, Toshiaki, Matsumoto, Toshio, Onishi, Yosuke, Shirahata, Mai, Tsumura, Kohji, and Wada, Takehiko
- Subjects
Brightness ,Cosmology and Nongalactic Astrophysics (astro-ph.CO) ,media_common.quotation_subject ,Astrophysics::High Energy Astrophysical Phenomena ,FOS: Physical sciences ,Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,01 natural sciences ,Photometry (optics) ,0103 physical sciences ,dark ages, reionization, first stars ,010303 astronomy & astrophysics ,Reionization ,Astrophysics::Galaxy Astrophysics ,media_common ,Physics ,Zodiacal light ,010308 nuclear & particles physics ,zodiacal dust ,Astrophysics::Instrumentation and Methods for Astrophysics ,Astronomy and Astrophysics ,infrared: diffuse background ,Astrophysics - Astrophysics of Galaxies ,Galaxy ,diffuse radiation ,Stars ,Extragalactic background light ,Space and Planetary Science ,Sky ,cosmology: observations ,Astrophysics of Galaxies (astro-ph.GA) ,Astrophysics::Earth and Planetary Astrophysics ,infrared: general ,Astrophysics - Cosmology and Nongalactic Astrophysics - Abstract
著者人数: 15名, Accepted: 2017-03-19, 資料番号: SA1170033000
- Published
- 2017
8. Co-orbital Asteroids as the Source of Venus's Zodiacal Dust Ring
- Author
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Petr Pokorný and Marc J. Kuchner
- Subjects
Solar System ,010504 meteorology & atmospheric sciences ,media_common.quotation_subject ,Population ,FOS: Physical sciences ,Venus ,01 natural sciences ,0103 physical sciences ,Astrophysics::Solar and Stellar Astrophysics ,education ,010303 astronomy & astrophysics ,0105 earth and related environmental sciences ,media_common ,Earth and Planetary Astrophysics (astro-ph.EP) ,Physics ,education.field_of_study ,Zodiacal light ,biology ,Meteoroid ,Astronomy ,Astronomy and Astrophysics ,biology.organism_classification ,Orbit ,Space and Planetary Science ,Asteroid ,Sky ,Physics::Space Physics ,Astrophysics::Earth and Planetary Astrophysics ,Astrophysics - Earth and Planetary Astrophysics - Abstract
Photometry from the Helios and STEREO spacecraft revealed regions of enhanced sky surface-brightness suggesting a narrow circumsolar ring of dust associated with Venus's orbit. We model this phenomenon by integrating the orbits of 10,000,000+ dust particles subject to gravitational and non-gravitational forces, considering several different kinds of plausible dust sources. We find that only particles from a hypothetical population of Venus co-orbital asteroids can produce enough signal in a narrow ring to match the observations. Previous works had suggested such objects would be dynamically unstable. However, we re-examined the stability of asteroids in 1:1 resonance with Venus and found that ~8% should survive for the age of the solar system, enough to supply the observed ring., 18 pages, 7 figures, Published in The Astrophysical Journal Letters
- Published
- 2019
9. Zodiacal Exoplanets in Time (ZEIT). VIII. A Two-planet System in Praesepe from K2 Campaign 16
- Author
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Adam L. Kraus, Aaron C. Rizzuto, Andrew Vanderburg, Marcel A. Agüeros, Courtney D. Dressing, Andrew W. Mann, Stephanie T. Douglas, and Daniel M. Krolikowski
- Subjects
Earth and Planetary Astrophysics (astro-ph.EP) ,Physics ,Zodiacal light ,010504 meteorology & atmospheric sciences ,FOS: Physical sciences ,Astronomy ,Astronomy and Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Radius ,Planetary system ,01 natural sciences ,Exoplanet ,Radial velocity ,Stars ,Space and Planetary Science ,Planet ,0103 physical sciences ,Astrophysics::Solar and Stellar Astrophysics ,Astrophysics::Earth and Planetary Astrophysics ,010303 astronomy & astrophysics ,Astrophysics::Galaxy Astrophysics ,Astrophysics - Earth and Planetary Astrophysics ,0105 earth and related environmental sciences ,Open cluster - Abstract
Young planets offer a direct view of the formation and evolution processes that produced the diverse population of mature exoplanet systems known today. The repurposed Kepler mission K2 is providing the first sample of young transiting planets by observing populations of stars in nearby, young clusters or stellar associations. We report the detection and confirmation of two planets transiting K2-264, an M2.5 dwarf in the 650 Myr old Praesepe open cluster. Using our notch-filter search method on the K2 lightcurve, we identify planets with periods of 5.84 d and 19.66 d. This is currently the second known multi-transit system in open clusters younger than 1 Gyr. The inner planet has a radius of 2.27$_{-0.16}^{+0.20}$ R$_\oplus$ and the outer planet has a radius of 2.77$_{-0.18}^{+0.20}$ R$_\oplus$. Both planets are likely mini-Neptunes. These planets are expected to produce radial velocity signals of 3.4 and 2.7 m/s respectively, which is smaller than the expected stellar variability in the optical ($\simeq$30 m/s), making mass measurements unlikely in the optical, but possible with future near-infrared spectrographs. We use an injection-recovery test to place robust limits on additional planets in the system, and find that planets larger than 2 R$_\oplus$ with periods of 1-20 d are unlikely., Comment: 13 pages, 12 figures, 2 tables, accepted for publication in AJ
- Published
- 2018
10. Zodiacal Light Beyond Earth Orbit Observed with Pioneer 10
- Author
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Matsuoka, Y., Pyo, J., Matsumoto, Toshio, and Tsumura, Koji
- Subjects
Brightness ,010504 meteorology & atmospheric sciences ,FOS: Physical sciences ,Interplanetary medium ,Astrophysics::Cosmology and Extragalactic Astrophysics ,01 natural sciences ,Sky brightness ,0103 physical sciences ,010303 astronomy & astrophysics ,Astrophysics::Galaxy Astrophysics ,0105 earth and related environmental sciences ,Earth and Planetary Astrophysics (astro-ph.EP) ,Physics ,Earth's orbit ,Zodiacal light ,zodiacal dust ,Astrophysics::Instrumentation and Methods for Astrophysics ,Ecliptic ,Astronomy ,Astronomy and Astrophysics ,asteroids: general ,Extragalactic background light ,Space and Planetary Science ,Asteroid ,Physics::Space Physics ,minor planets ,85A04 (Primary), 85A99 (Secondary) ,Astrophysics::Earth and Planetary Astrophysics ,interplanetary medium ,Astrophysics - Earth and Planetary Astrophysics - Abstract
We reanalyze the Imaging Photopolarimeter data from Pioneer 10 to study the zodiacal light in the B and R bands beyond Earth orbit, applying an improved method to subtract integrated star light (ISL) and diffuse Galactic light (DGL). We found that there exists a significant instrumental offset, making it difficult to examine the absolute sky brightness. Instead, we analyzed the differential brightness, i.e., the difference in sky brightness from the average at high ecliptic latitude, and compared with that expected from the model zodiacal light. At a heliocentric distance of r3 au, as previously reported. However, a clear discrepancy from the model is found at r=2.94 au which indicates the existence of a local dust cloud produced by the collision of asteroids or dust trail from active asteroids (or main-belt comets). Our result confirms that the main component of the zodiacal light (smooth cloud) is consistent with the model even beyond the earth orbit, which justifies the detection of the extragalactic background light after subtracting the zodiacal light based on the model., 13 pages, 8 figures
- Published
- 2018
11. COMETARY ORIGIN OF THE ZODIACAL CLOUD AND CARBONACEOUS MICROMETEORITES. IMPLICATIONS FOR HOT DEBRIS DISKS
- Author
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David Nesvorný, Peter Jenniskens, Harold F. Levison, William F. Bottke, David Vokrouhlický, and Matthieu Gounelle
- Subjects
Physics ,Solar System ,Zodiacal light ,Outer planets ,Epoch (reference date) ,Astronomy ,Astronomy and Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Debris ,Stars ,Space and Planetary Science ,Asteroid ,Physics::Space Physics ,Astrophysics::Solar and Stellar Astrophysics ,Astrophysics::Earth and Planetary Astrophysics ,Late Heavy Bombardment ,Astrophysics::Galaxy Astrophysics - Abstract
The zodiacal cloud is a thick circumsolar disk of small debris particles produced by asteroid collisions and comets. Here, we present a zodiacal cloud model based on the orbital properties and lifetimes of comets and asteroids, and on the dynamical evolution of dust after ejection. The model is quantitatively constrained by IRAS observations of thermal emission, but also qualitatively consistent with other zodiacal cloud observations. We find that 85-95% of the observed mid-infrared emission is produced by particles from the Jupiter-family comets (JFCs) and $ 10^4$ times brighter during the Late Heavy Bombardment (LHB) epoch $\approx$3.8 Gyr ago, when the outer planets scattered numerous comets into the inner solar system. The bright debris disks with a large 24-$\mu$m excess observed around mature stars may be an indication of massive cometary populations existing in those systems.
- Published
- 2010
12. CONSTRUCTION OF AN EARTH MODEL: ANALYSIS OF EXOPLANET LIGHT CURVES AND MAPPING THE NEXT EARTH WITH THE NEW WORLDS OBSERVER
- Author
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Webster Cash and Phil Oakley
- Subjects
Physics ,Zodiacal light ,Space and Planetary Science ,Observatory ,Planet ,Orientation (computer vision) ,Astronomy and Astrophysics ,Terrain ,Astrophysics::Earth and Planetary Astrophysics ,Light curve ,Rotation ,Exoplanet ,Remote sensing - Abstract
The orbital light curve of a terrestrial exoplanet will likely contain valuable information about the surface and atmospheric features of the planet, both in its overall shape and hourly variations. We have constructed an empirically based code capable of simulating observations of the Earth from any orientation, at any time of year with continuously updated cloud and snow coverage with a New Worlds Observatory. By simulating these observations over a full orbital revolution at a distance of 10 pc we determine that the detection of an obliquity or seasonal terrain change is possible at low inclinations. In agreement with other studies, a 4 m New Worlds Observer can accurately determine the rotation rate of the planet at a success rate from ~30% to 80% with only 5 days of observations depending on the signal to noise of the observations. We also attempt simple inversions of these diurnal light curves to sketch a map of the reflecting planet's surface features. This mapping technique is only successful with highly favorable systems and in particular requires that the cloud coverage must be lower than the Earth's average. Our test case of a 2 M ⊕ planet at 7 pc distance with low exo-zodiacal light and 25% cloud coverage produced crude, but successful results. Additionally, with these highly favorable systems NWO may be able to discern the presence of liquid surface water (or other smooth surfaces) though it requires a complex detection available only at crescent phases in high inclination systems.
- Published
- 2009
13. HOT DEBRIS DUST AROUND HD 106797
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Takanori Hirao, Hideaki Fujiwara, Takafumi Ootsubo, Hiroshi Murakami, Keigo Enya, Takashi Onaka, Takao Nakagawa, Hirokazu Kataza, Misato Fukagawa, Glenn J. White, Takuya Yamashita, Daisuke Ishihara, and Jonathan P. Marshall
- Subjects
Earth and Planetary Astrophysics (astro-ph.EP) ,Physics ,Debris disk ,Zodiacal light ,FOS: Physical sciences ,Astronomy and Astrophysics ,Astrophysics ,Radius ,Debris ,Luminosity ,Photometry (optics) ,Astrophysics - Solar and Stellar Astrophysics ,Space and Planetary Science ,Stellar evolution ,Solar and Stellar Astrophysics (astro-ph.SR) ,Main sequence ,Astrophysics - Earth and Planetary Astrophysics - Abstract
著者人数:13名, Accepted: 2009-03-06, 資料番号: SA1000761000
- Published
- 2009
14. OBSERVATIONS OF MAIN-SEQUENCE STARS AND LIMITS ON EXOZODICAL DUST WITH NULLING INTERFEROMETRY
- Author
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Doug Miller, William F. Hoffmann, Guido Brusa, Philip M. Hinz, W. M. Liu, and Matthew A. Kenworthy
- Subjects
Physics ,Debris disk ,Stars ,Zodiacal light ,Space and Planetary Science ,Circumstellar dust ,Astronomy ,Astronomy and Astrophysics ,Context (language use) ,Astrophysics ,Circumstellar habitable zone ,Main sequence ,Cosmic dust - Abstract
We present nulling interferometric observations of six nearby main-sequence stars (α CrB, α Lyr, β Leo, γ Ser, Eri, and ζ Lep). None of the stars show evidence for a positive detection of warm debris in the habitable zone of the systems. Using a scaled up model of solar zodiacal emission, the 3σ upper limits on dust density range from 220 to 104 Zody (1 Zody = the density of our own solar zodiacal cloud) depending on the particular star, corresponding to mass limits of 10–7 to 10–5 M ⊕ of micron-sized dust. These limits contrast with the presence of dust at greater separations from the star, implying a clearing in dust in the inner system. This suggests that the inner circumstellar environment around nearby intermediate-mass main-sequence stars more than several tens of millions of years old are generally cleared of dusty debris. Finally, the well studied nature of the debris disks around Vega, Eridani, and ζ Leporis allows us to place these 10 μm nulling observations in the context of previous studies to determine the physical processes responsible for shaping the debris disk in these particular systems.
- Published
- 2009
15. GALEXOBSERVATIONS OF DIFFUSE UV RADIATION AT HIGH SPATIAL RESOLUTION FROM THE SANDAGE NEBULOSITY
- Author
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Abhay Karnataki, N. V. Sujatha, Jayant Murthy, Richard C. Henry, and Luciana Bianchi
- Subjects
Physics ,Zodiacal light ,Forward scatter ,Scattering ,Astrophysics (astro-ph) ,Airglow ,FOS: Physical sciences ,Astronomy and Astrophysics ,Astrophysics ,Radiation ,medicine.disease_cause ,Starlight ,Space and Planetary Science ,medicine ,Ultraviolet ,Cosmic dust - Abstract
Using the GALEX ultraviolet imagers we have observed a region of nebulosity first identified as starlight scattered by interstellar dust by Sandage (1976). Apart from airglow and zodiacal emission, we have found a diffuse UV background of between 500 and 800 \phunit in both the \galex FUV (1350 -- 1750 \AA) and NUV (1750 -- 2850 \AA). Of this emission, up to 250 \phunit is due to \htwo fluorescent emission in the FUV band; the remainder is consistent with scattering from interstellar dust. We have estimated the optical constants to be $a = 0.3; g = 0.7$ in the FUV and $a = 0.5; g = 0.7$ in the NUV, implying highly forward scattering grains, plus an extragalactic contribution of as much as 150 \phunit. These are the highest spatial resolution observations of the diffuse UV background to date and show an intrinsic scatter beyond that expected from instrumental noise alone. Further modeling is required to understand the nature of this scatter and its implications for the ISM., Comment: Total 20 pages, Figures 9, Accepted for publication in Astrophysical Journal
- Published
- 2009
16. Probing the 3.6 μm CIRB withSpitzerin Three DIRBE Dark Spots
- Author
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L.R. Levenson and Edward L. Wright
- Subjects
Physics ,Zodiacal light ,media_common.quotation_subject ,Astronomy and Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Astrophysics ,Power law ,Galaxy ,Photometry (optics) ,Extended Groth Strip ,Space and Planetary Science ,Sky ,Cosmic infrared background ,Magnitude (astronomy) ,Astrophysics::Earth and Planetary Astrophysics ,Astrophysics::Galaxy Astrophysics ,media_common - Abstract
We observed three regions of the sky with Spitzer in which the Cosmic InfraRed Background (CIRB) has been determined at 3.5 microns using the method of subtracting 2MASS stellar fluxes from zodiacal light subtracted DIRBE maps. For each of these regions we have obtained 270 seconds of integration time per pixel with IRAC on Spitzer over the central square degree. We present galaxy counts in each of these approximately 1 square degree IRAC surveys. Along with deep galaxy counts in the Extended Groth Strip and GOODS North, we are able to compare the galactic contribution to the CIRB with the "DIRBE minus 2MASS'' determined L-band CIRB. Using the profile-fit photometry package GIM2D, we find a substantially larger flux contribution to the CIRB than that determined using aperture photometry. We have also made the first rigorous analysis of the uncertainties in determining the CIRB via galaxy counts in Spitzer images using a Monte Carlo Markov Chain simulation of our data analysis. Using a simple broken power law model for galaxy counts as a function of magnitude we find a most probable contribution to the CIRB from galaxies at 3.6 microns of 10.8^{+2.1}_{-1.1} kJy/sr. Even with this restricted model, however, we find that galaxy counting does not strongly constrain the CIRB from above. We are able to find solutions in which the CIRB runs away to large intensities without the need for an additional diffuse source.
- Published
- 2008
17. The Optical Extragalactic Background Light: Revisions and Further Comments
- Author
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Rebecca A. Bernstein
- Subjects
Physics ,Zodiacal light ,Amplitude ,Extragalactic background light ,Space and Planetary Science ,Scattering ,Diffuse sky radiation ,Astronomy ,Astronomy and Astrophysics ,Context (language use) ,Astrophysics ,Surface brightness ,Galaxy - Abstract
We revise the measurements in our previous work of foreground zodiacal light (ZL) and diffuse Galactic light (DGL) that were used to measure the extragalactic background light (EBL). These changes result in a decrease of 8 and an increase of 0.3 in units of 10-9 ergs s-1 cm-2 sr-1 A-1 ("cgs" units) in the ZL and DGL flux, respectively. We therefore obtain revised values for the EBL of 6 ± 4, 10 ± 5, and 7 ± 4 cgs in the HST WFPC2 U (F300W), V (F555W), and I (F814W) bands, respectively, from sources fainter than mV ~ 23 AB mag. The revisions are dominated by the details of the tropospheric scattering models used to measure the ZL. We discuss these results in the context of faint number counts and diffuse EBL measurements at other wavelengths. In particular, we note that unless the slope of the galaxy counts increases beyond mV ~ 30 AB mag, unresolved sources will contribute
- Published
- 2007
18. Signatures of recent asteroid disruptions in the formation and evolution of solar system dust bands
- Author
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A. J. Espy Kehoe, Stanley F. Dermott, Joshua Colwell, and T. J. J. Kehoe
- Subjects
Physics ,Earth and Planetary Astrophysics (astro-ph.EP) ,Solar System ,Zodiacal light ,Zodiacal dust ,Planets and satellites - dynamical evolution and stability ,Ecliptic ,FOS: Physical sciences ,Astronomy and Astrophysics ,Astrophysics ,Escape velocity ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Regolith ,complex mixtures ,Space and Planetary Science ,Asteroid ,Celestial mechanics ,Cluster (physics) ,Particle ,Astrophysics::Solar and Stellar Astrophysics ,Astrophysics::Earth and Planetary Astrophysics ,Minor planets - asteroids - general ,Astrophysics::Galaxy Astrophysics ,Astrophysics - Earth and Planetary Astrophysics - Abstract
We have performed detailed dynamical modeling of the structure of a faint dust band observed in coadded IRAS data at an ecliptic latitude of 17$^{\circ}$ that convincingly demonstrates that it is the result of a relatively recent (significantly less than 1 Ma) disruption of an asteroid and is still in the process of forming. We show here that young dust bands retain information on the size distribution and cross-sectional area of dust released in the original asteroid disruption, before it is lost to orbital and collisional decay. We find that the Emilkowalski cluster is the source of this partial band and that the dust released in the disruption would correspond to a regolith layer $\sim$3 m deep on the $\sim$10 km diameter source body's surface. The dust in this band is described by a cumulative size-distribution inverse power-law index with a lower bound of 2.1 (implying domination of cross-sectional area by small particles) for dust particles with diameters ranging from a few $\mu$m up to a few cm. The coadded observations show that the thermal emission of the dust band structure is dominated by large (mm--cm size) particles. We find that dust particle ejection velocities need to be a few times the escape velocity of the Emilkowalski cluster source body to provide a good fit to the inclination dispersion of the observations. We discuss the implications that such a significant release of material during a disruption has for the temporal evolution of the structure, composition, and magnitude of the zodiacal cloud., Comment: Published by ApJ, 16 pages, 14 figures
- Published
- 2015
19. Observing the Zodiacal Light.
- Author
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O'Meara, Stephen James
- Subjects
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ZODIACAL light , *ASTRONOMY - Abstract
Focuses on the observations of zodiacal light. Months where the zodiacal light is very visible; Characteristics of zodiacal lights; Factors that contribute to the brightness of zodiacal lights. INSET: Montezuma and the Zodiacal Light.
- Published
- 2000
20. Theoretical Limits on Extrasolar Terrestrial Planet Detection with Coronagraphs
- Author
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Benoît Collins, Stephen T. Ridgway, Marc J. Kuchner, Eugene Pluzhnik, and Olivier Guyon
- Subjects
Physics ,Solar System ,Zodiacal light ,Astrophysics (astro-ph) ,Astrophysics::Instrumentation and Methods for Astrophysics ,FOS: Physical sciences ,Astronomy and Astrophysics ,Astrophysics ,law.invention ,Telescope ,Stars ,Space and Planetary Science ,law ,Angular diameter ,Planet ,Physics::Space Physics ,Astrophysics::Solar and Stellar Astrophysics ,Terrestrial planet ,Astrophysics::Earth and Planetary Astrophysics ,Coronagraph - Abstract
Many high contrast coronagraph designs have recently been proposed. In this paper, their suitability for direct imaging of extrasolar terrestrial planets is reviewed. We also develop a linear-algebra based model of coronagraphy that can both explain the behavior of existing coronagraphs and quantify the coronagraphic performance limit imposed by fundamental physics. We find that the maximum theoretical throughput of a coronagraph is equal to one minus the non-aberrated non-coronagraphic PSF of the telescope. We describe how a coronagraph reaching this fundamental limit may be designed, and how much improvement over the best existing coronagraph design is still possible. Both the analytical model and numerical simulations of existing designs also show that this theoretical limit rapidly degrades as the source size is increased: the ``highest performance'' coronagraphs, those with the highest throughput and smallest Inner Working Angle (IWA), are the most sensitive to stellar angular diameter. This unfortunately rules out the possibility of using a small IWA (lambda/d) coronagraph for a terrestrial planet imaging mission. Finally, a detailed numerical simulation which accurately accounts for stellar angular size, zodiacal and exozodiacal light is used to quantify the efficiency of coronagraph designs for direct imaging of extrasolar terrestrial planets in a possible real observing program. We find that in the photon noise limited regime, a 4m telescope with a theoretically optimal coronagraph is able to detect Earth-like planets around 50 stars with 1hr exposure time per target (assuming 25% throughput and exozodi levels similar to our solar system). We also show that at least 2 existing coronagraph design can approach this level of performance in the ideal monochromatic case considered in this study., Accepted for publication to ApJ Supp
- Published
- 2006
21. IRS Spectra of Solar‐Type Stars: A Search for Asteroid Belt Analogs
- Author
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G. Bryden, C. A. Beichman, Michael W. Werner, George H. Rieke, Angelle Tanner, Thomas N. Gautier, David Trilling, Karl R. Stapelfeldt, and Samantha Lawler
- Subjects
Physics ,Solar System ,Zodiacal light ,Astrophysics (astro-ph) ,FOS: Physical sciences ,Astronomy and Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Astrophysics ,Planetary system ,Radial velocity ,Photometry (astronomy) ,Stars ,Space and Planetary Science ,Asteroid ,Astrophysics::Solar and Stellar Astrophysics ,Asteroid belt ,Astrophysics::Earth and Planetary Astrophysics ,Astrophysics::Galaxy Astrophysics - Abstract
We report the results of a spectroscopic search for debris disks surrounding 41 nearby solar-type stars, including eight planet-bearing stars, using the Infrared Spectrometer (IRS) on the Spitzer Space Telescope. With the accurate relative photometry of the IRS between 7 and 34 μm we are able to look for excesses as small as ~2% of photospheric levels, with particular sensitivity to weak spectral features. For stars with no excess, the 3 σ upper limit in a band at 30-34 μm corresponds to ~75 times the brightness of our zodiacal dust cloud. Comparable limits at 8.5-13 μm correspond to ~1400 times the brightness of our zodiacal dust cloud. These limits correspond to material located within the
- Published
- 2006
22. Is There an Imprint of Primordial Stars in the TeV γ‐Ray Spectrum of Blazars?
- Author
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Eli Dwek, Frank Krennrich, and Richard G. Arendt
- Subjects
Physics ,education.field_of_study ,Zodiacal light ,Astrophysics::High Energy Astrophysical Phenomena ,Astrophysics (astro-ph) ,Population ,FOS: Physical sciences ,Astronomy and Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Astrophysics ,Redshift ,Spectral line ,Galaxy ,Stars ,Extragalactic background light ,Space and Planetary Science ,Astrophysics::Earth and Planetary Astrophysics ,Blazar ,education ,Astrophysics::Galaxy Astrophysics - Abstract
The 1 - 5 micron diffuse sky emission from which local foreground emission from the solar system and the Galaxy have been subtracted exceeds the brightness that can be attributed to normal star forming galaxies. The nature of this excess near-infrared background light (NIRBL) is still controversial. On one hand, it has been interpreted as a distinct spectral feature created by the redshifted emission from primordial (Population III) stars that have formed at redshifts > 8. On the other hand, the NIRBL spectrum is almost identical to that of the zodiacal cloud, raising the possibility that it is of local origin. Blazars can, in principle, offer a simple test for the nature and origin of the NIRBL. Very high energy gamma-ray photons emitted by these objects are attenuated on route to earth by photon-photon interactions with the extragalactic background light (EBL). This paper examines whether the extragalactic nature of the NIRBL can be determined from the analysis of the TeV spectra of blazars. (Abridged), 16 pages, 8 figures, accepted for publication in the ApJ on July 15, 2005
- Published
- 2005
23. Corrections of Errors in 'The First Detections of the Extragalactic Background Light at 3000, 5500, and 8000 A. I, II, and III' (ApJ, 571; 56, 85, 107 [2002])
- Author
-
Rebecca A. Bernstein, Barry F. Madore, and Wendy L. Freedman
- Subjects
Physics ,Zodiacal light ,Extragalactic background light ,Series (mathematics) ,Space and Planetary Science ,Flux ,Astronomy and Astrophysics ,Astrophysics - Abstract
We correct errors in a series of papers in which we described observations of the optical extragalactic background light (EBL). These errors pertain to the measurement of zodiacal light, given in the second paper of this series. Making these corrections leads to a net decrease of 0.5(� 0.6)% in our zodiacal light measurement and a corresponding increase in the inferred extragalactic background light of roughly 0:5(� 0:6) ; 10 � 9 ergs s � 1 cm � 2 sr � 1 8 � 1 . For comparison, the originally quoted EBL flux at 5500 8 was 2:7(� 1:4) ; 10 � 9 in the same units (1 � combined systematic and statistical uncertainty). We provide a detailed discussion of these errors and also discuss the evolution ofthisworkpriortothe2002papers.Wenotethatcorrectionsofthefactualerrorsinour2002papersyieldaresultthat is consistent with the results and errors quoted there. However, this is not intended to be a new or updated analysis, and it does not address some methodological objections which have been raised to our prior work.
- Published
- 2005
24. Infrared Telescope in Space Observations of the Near‐Infrared Extragalactic Background Light
- Author
-
Freund, M., Lim, M., Cohen, M., Matsumoto, Toshio, Matsuura, Shuji, Murakami, Hiroshi, Tanaka, Masahiro, Kawada, Mitsunobu, and Noda, Manabu
- Subjects
Physics ,Zodiacal light ,Astrophysics::High Energy Astrophysical Phenomena ,Cosmic microwave background ,Astrophysics::Instrumentation and Methods for Astrophysics ,Astronomy and Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Astrophysics ,Galaxy ,Redshift ,Stars ,Extragalactic background light ,Space and Planetary Science ,Sky brightness ,Astrophysics::Earth and Planetary Astrophysics ,Reionization ,Astrophysics::Galaxy Astrophysics - Abstract
Accepted: 2005-02-02, 資料番号: SA1003393000
- Published
- 2005
25. The Spitzer First Look Survey—Ecliptic Plane Component: Asteroids and Zodiacal Background
- Author
-
Bidushi Bhattacharya, Jon D. Giorgini, William T. Reach, S. R. Tyler, J. L. Elliot, Alberto Noriega-Crespo, Luisa Rebull, Victoria S. Meadows, C. Grillmair, and E. L. Ryan
- Subjects
Physics ,education.field_of_study ,Zodiacal light ,Infrared ,media_common.quotation_subject ,Population ,Ecliptic ,Astronomy ,Flux ,Astronomy and Astrophysics ,Astrophysics ,Latitude ,Space and Planetary Science ,Asteroid ,Sky ,education ,media_common - Abstract
The Spitzer First Look Survey (FLS) provided an initial characterization of the infrared sky at Spitzer wavelengths and sensitivities. The ecliptic plane component (EPC) of the FLS concentrated on two 0.13 deg2 fields at a solar elongation of 115° and ecliptic latitudes (β) of 0° and +5°. The FLS-EPC explored the small asteroid counts at 8 and 24 μm, with a detection limit down to ~0.08 and 0.8 mJy, respectively, and a completeness limit almost twice as deep as the 8 μm equivalent flux density of the previous deepest mid-IR survey. The FLS-EPC also provided initial characterization of the zodiacal light near the ecliptic plane. Fifteen known and 19 unknown asteroids were identified, and asteroids detected at both wavelengths displayed similar 8 to 24 μm flux ratios of ~0.1. Comparing number counts for the β = 0° and +5° fields indicates a slower-than-anticipated drop-off in contrast to predicted scale heights, possibly due to the presence of higher inclination objects in the small population sampled by Spitzer. The measured zodiacal light background was found to be within 5% of Spitzer model predictions at 24 μm.
- Published
- 2004
26. Adaptive Optics Nulling Interferometric Constraints on the Mid-Infrared Exozodiacal Dust Emission around Vega
- Author
-
William F. Hoffmann, Patrick C. McGuire, James Roger P. Angel, Guido Brusa, Matthew A. Kenworthy, W. M. Liu, Francois Wildi, Michael Lloyd-Hart, Doug Miller, and Philip M. Hinz
- Subjects
Physics ,Solar System ,Zodiacal light ,Astrophysics (astro-ph) ,Exozodiacal dust ,Vega ,Mid infrared ,FOS: Physical sciences ,Astronomy and Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Astrophysics ,Interferometry ,Space and Planetary Science ,Astrophysics::Solar and Stellar Astrophysics ,Astrophysics::Earth and Planetary Astrophysics ,Secondary mirror ,Adaptive optics ,Astrophysics::Galaxy Astrophysics - Abstract
We present the results of mid-infrared nulling interferometric observations of the main-sequence star alpha Lyr (Vega) using the 6.5 m MMT with its adaptive secondary mirror. From the observations at 10.6 microns, we find that there is no resolved emission from the circumstellar environment (at separations greater than 0.8 AU) above 2.1% (3 sigma limit) of the level of the stellar photospheric emission. Thus, we are able to place an upper limit on the density of dust in the inner system of 650 times that of our own solar system's zodiacal cloud. This limit is roughly 2.8 times better than those determined with photometric excess observations such as those by IRAS. Comparison with far-infrared observations by IRAS shows that the density of warm dust in the inner system (< 30 AU) is significantly lower than cold dust at larger separations. We consider two scenarios for grain removal, the sublimation of ice grains and the presence of a planetary mass "sweeper." We find that if sublimation of ice grains is the only removal process, a large fraction (> 80%) of the material in the outer system is ice., 11 pages, 1 figure, Accepted to The Astrophysical Journal Letters
- Published
- 2004
27. Classification of Spectra from the Infrared Space Observatory PHT‐S Database
- Author
-
Stephan D. Price, H. Walker, Kathleen E. Kraemer, and Tracy M. Hodge
- Subjects
Physics ,Zodiacal light ,Spectrometer ,Infrared ,Astrophysics::Instrumentation and Methods for Astrophysics ,Astronomy ,Infrared spectroscopy ,Astronomy and Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Astrophysics ,Spectral line ,Space observatory ,Spectral database ,Wavelength ,Space and Planetary Science ,Astrophysics::Earth and Planetary Astrophysics ,Astrophysics::Galaxy Astrophysics - Abstract
We have classified over 1500 infrared spectra obtained with the PHT-S spectrometer aboard the Infrared Space Observatory according to the system developed for the Short Wavelength Spectrometer (SWS) spectra by Kraemer et al. The majority of these spectra contribute to subclasses that are either underrepresented in the SWS spectral database or contain sources that are too faint, such as M dwarfs, to have been observed by either the SWS or the Infrared Astronomical Satellite Low Resolution Spectrometer. There is strong overall agreement about the chemistry of objects observed with both instruments. Discrepancies can usually be traced to the different wavelength ranges and sensitivities of the instruments. Finally, a large subset of the observations (250 spectra) exhibit a featureless, red continuum that is consistent with emission from zodiacal dust and suggest directions for further analysis of this serendipitous measurement of the zodiacal background.
- Published
- 2004
28. The Wisconsin Hα Mapper Northern Sky Survey
- Author
-
L. M. Haffner, R. J. Reynolds, S. L. Tufte, G. J. Madsen, K. P. Jaehnig, and J. W. Percival
- Subjects
Physics ,Spiral galaxy ,Zodiacal light ,010504 meteorology & atmospheric sciences ,media_common.quotation_subject ,Local standard of rest ,Astronomy and Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Astrophysics ,Galactic plane ,01 natural sciences ,Orion–Eridanus Superbubble ,Galaxy ,Space and Planetary Science ,Sky ,0103 physical sciences ,Spectral resolution ,010303 astronomy & astrophysics ,Astrophysics::Galaxy Astrophysics ,0105 earth and related environmental sciences ,media_common - Abstract
The Wisconsin H-Alpha Mapper (WHAM) has surveyed the distribution and kinematics of ionized gas in the Galaxy above declination -30 degrees. The WHAM Northern Sky Survey (WHAM-NSS) has an angular resolution of one degree and provides the first absolutely-calibrated, kinematically-resolved map of the H-Alpha emission from the Warm Ionized Medium (WIM) within ~ +/-100 km/s of the Local Standard of Rest. Leveraging WHAM's 12 km/s spectral resolution, we have modeled and removed atmospheric emission and zodiacal absorption features from each of the 37,565 spectra. The resulting H-Alpha profiles reveal ionized gas detected in nearly every direction on the sky with a sensitivity of 0.15 R (3 sigma). Complex distributions of ionized gas are revealed in the nearby spiral arms up to 1-2 kpc away from the Galactic plane. Toward the inner Galaxy, the WHAM-NSS provides information about the WIM out to the tangent point down to a few degrees from the plane. Ionized gas is also detected toward many intermediate velocity clouds at high latitudes. Several new H II regions are revealed around early B-stars and evolved stellar cores (sdB/O). This work presents the details of the instrument, the survey, and the data reduction techniques. The WHAM-NSS is also presented and analyzed for its gross properties. Finally, some general conclusions are presented about the nature of the WIM as revealed by the WHAM-NSS.
- Published
- 2003
29. Has the Optical Extragalactic Background Light Been Detected?
- Author
-
Kalevi Mattila
- Subjects
Physics ,Zodiacal light ,Line-of-sight ,010308 nuclear & particles physics ,Astronomy and Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Astrophysics ,01 natural sciences ,Critical discussion ,Freedman ,Extragalactic background light ,Space and Planetary Science ,0103 physical sciences ,Astrophysics::Earth and Planetary Astrophysics ,Scattered light ,010303 astronomy & astrophysics ,Astrophysics::Galaxy Astrophysics - Abstract
A critical discussion is presented of the data analysis applied by Bernstein, Freedman and Madore (2002 ApJ, 571, 56; and ApJ 571, 85) in their measurement of the Extragalactic Background Light. There are questionable assumptions in the analysis of the ground-based observations of the Zodiacal Light. The modeling of the Diffuse Galactic Light is based on an underestimated value of the dust column density along the line of sight. Comparison with the previously presented results from the same observations reveals a puzzling situation: in spite of a large difference in the atmospheric scattered light corrections the derived Extragalactic Background Light values are exactly the same. The claim of the paper of a ``detection of the Extragalactic Background Light'' appears premature.
- Published
- 2003
30. [ITAL]Midcourse Space Experiment[/ITAL] Mid-Infrared Measurements of the Thermal Emission from the Zodiacal Dust Cloud
- Author
-
Paul V. Noah, Russell G. Walker, Don Mizuno, Sumita Jayaraman, Stephan D. Price, and Physics of Living Systems
- Subjects
Physics ,Infrared astronomy ,Zodiacal light ,Diffuse Infrared Background Experiment ,Space and Planetary Science ,Cosmic infrared background ,Ecliptic ,Astronomy ,Interplanetary medium ,Astronomy and Astrophysics ,Satellite ,Astrophysics ,Spectral bands - Abstract
The Midcourse Space Experiment (MSX) sampled the mid-infrared thermal emission from the zodiacal dust cloud in spectral bands centered at 8.3, 12, 15, and 21 μm with a variety of experiments during a 9 month period in 1996. Seventy ecliptic latitude profiles were measured between Sun-centered longitudes of 98° and 335°, and a single longitudinal scan was obtained along the ecliptic plane between 160° and 330° solar elongations. These observations complement the contiguous Infrared Astronomy Satellite and Diffuse Infrared Background Experiment (DIRBE) Cosmic Background Explorer surveys by extending the mid-infrared coverage beyond the solar exclusion limits of these experiments and measuring the emission at much higher spatial resolution. The MSX observations are at high sensitivity, ~2 × 10-12 cm-2 μm sr-1, and spatial resolution, 2' to 3'. The MSX and DIRBE measurements are in good agreement where they do overlap. We describe the data processing that created the database and the estimated accuracy and precision.
- Published
- 2003
31. Analysis of the Diffuse Near‐Infrared Emission from Two‐Micron All‐Sky Survey Deep Integration Data: Foregrounds versus the Cosmic Infrared Background
- Author
-
John C. Mather, A. Kashlinsky, Roc M. Cutri, Mike Skrutskie, and S. Odenwald
- Subjects
Physics ,Zodiacal light ,Point source ,media_common.quotation_subject ,Spectral density ,Astronomy and Astrophysics ,Astrophysics ,Galaxy ,Space and Planetary Science ,Sky ,Cosmic infrared background ,Surface brightness ,Noise (radio) ,media_common - Abstract
This is one of two papers in which we report the detection of structure in the cosmic infrared background (CIB) between 1.25 - 2.2 micron through the use of data from the Two Micron Sky Survey (2MASS). This paper concentrates on data assembly, analysis and the estimate of the various foreground contributions; the companion paper (Kashlinsky, Odenwald, Mather, Skrutskie, Cutri 2002, hereafter KOMSC) presents the cosmological results for the CIB fluctuations and their implications. By using repeated observations of a specific calibration star field, we were able to achieve integration times in excess of 3900 seconds compared to the 7.8 seconds in the standard 2MASS data product. This yielded a point source detection limit (3 \sigma) of +18.5^m in K_s band. The resulting co-added images were processed to remove point sources to a limiting surface brightness of +20^m/arcsec$^2 or 40 nW/m^2/sr. The remaining maps contained over 90% of the pixels and were Fourier transformed to study the spatial structure of the diffuse background light. After removing resolved sources and other artifacts, we find that the power spectrum of the final images has a power-law distribution consistent with clustering by distant galaxies. We estimate here the contributions to this signal from Galactic foregrounds, atmospheric OH-glow, zodiacal light and instrument noise, all of which are small and of different slopes. Hence, this supports the KOMSC identification of the signal as coming from the CIB fluctuations produced by distant clustered galaxies.
- Published
- 2003
32. The Zodiacal Emission Spectrum as Determined byCOBEand Its Implications
- Author
-
Eli Dwek and D. J. Fixsen
- Subjects
Physics ,Zodiacal light ,Interplanetary medium ,Astronomy ,Astronomy and Astrophysics ,Radius ,Astrophysics ,Interplanetary dust cloud ,Space and Planetary Science ,Asteroid ,Asteroid belt ,Astrophysics::Earth and Planetary Astrophysics ,Emission spectrum ,Astrophysics::Galaxy Astrophysics ,Cosmic dust - Abstract
We combine observations from the DIRBE and FIRAS instruments on the COBE satellite to derive an annually-averaged spectrum of the zodiacal cloud in the 10 to 1000 micron wavelength region. The spectrum exhibits a break at approx. 150 microns which indicates a sharp break in the dust size distribution at a radius of about 30 microns The spectrum can be fit with a single blackbody with a lambda(exp -2) emissivity law beyond 150 microns and a temperature of 240 K. We also used a more realistic characterization of the cloud to fit the spectrum, including a distribution of dust temperatures, representing different dust compositions and distances from the sun, as well as a realistic representation of the spatial distribution of the dust. We show that amorphous carbon and silicate dust with respective temperatures of 280 and 274 K at 1 AU, and size distributions with a break at grain radii of 14 and 32 microns, can provide a good fit to the average zodiacal dust spectrum. The total mass of the zodiacal cloud is 2 to 11 Eg (Eg=10(exp 18) g), depending on the grain composition. The lifetime of the cloud, against particle loss by Poynting- Robertson drag and the effects of solar wind, is about 10(exp 5) yr. The required replenishment rate is approx. 10(exp 14) g/yr. If this is provided by asteroid belt alone, the asteroids lifetime would be approx. 3 x 10(exp 10) yr. But comets and Kuiper belt objects may also contribute to the zodiacal cloud.
- Published
- 2002
33. The First Detections of the Extragalactic Background Light at 3000, 5500, and 8000 Å. II. Measurement of Foreground Zodiacal Light
- Author
-
Rebecca A. Bernstein, B. F. Madore, and Wendy L. Freedman
- Subjects
Physics ,Zodiacal light ,Astrophysics::High Energy Astrophysical Phenomena ,Astrophysics (astro-ph) ,Night sky ,Astrophysics::Instrumentation and Methods for Astrophysics ,Ecliptic ,FOS: Physical sciences ,Astronomy and Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Astrophysics ,Fraunhofer lines ,law.invention ,Telescope ,symbols.namesake ,Extragalactic background light ,Space and Planetary Science ,law ,Observatory ,symbols ,Astrophysics::Earth and Planetary Astrophysics ,Surface brightness ,Astrophysics::Galaxy Astrophysics - Abstract
We present a measurement of the absolute surface brightness of the zodiacal light (3900-5100A) toward a fixed extragalactic target at high ecliptic latitude based on moderate resolution (~1.3A per pixel) spectrophotometry obtained with the du Pont 2.5m telescope at Las Campanas Observatory in Chile. This measurement and contemporaneous Hubble Space Telescope data from WFPC2 and FOS comprise a coordinated program to measure the mean flux of the diffuse extragalactic background light (EBL). The zodiacal light at optical wavelengths results from scattering by interplanetary dust, so that the zodiacal light flux toward any extragalactic target varies seasonally with the position of the Earth. This measurement of zodiacal light is therefore relevant to the specific observations (date and target field) under discussion. To obtain this result, we have developed a technique that uses the strength of the zodiacal Fraunhofer lines to identify the absolute flux of the zodiacal light in the multiple-component night sky spectrum. Statistical uncertainties in the result are 0.6% (1 sigma). However, the dominant source of uncertainty is systematic errors, which we estimate to be 1.1% (1 sigma). We discuss the contributions included in this estimate explicitly. The systematic errors in this result contribute 25% in quadrature to the final error in our coordinated EBL measurement, which is presented in the first paper of this series., Accepted for publication in ApJ, 22 pages using emulateapj.sty, version with higher resolution figures available at http://www.astro.lsa.umich.edu/~rab/publications.html or at http://nedwww.ipac.caltech.edu/level5/Sep01/Bernstein2/frames.html
- Published
- 2002
34. The [ITAL]Infrared Space Observatory[/ITAL] Deep Asteroid Search
- Author
-
Edward F. Tedesco and François-Xavier Desert
- Subjects
Physics ,Wavelength ,Zodiacal light ,Space and Planetary Science ,Asteroid ,Infrared ,Equator ,Ecliptic ,Astronomy ,Flux ,Astronomy and Astrophysics ,Field of view ,Astrophysics - Abstract
A total of six deep exposures (using the astronomical observation template CAM01 with a 6'' pixel field of view) through the ISOCAM LW10 filter (IRAS band 1, i.e., 12 μm) were obtained on a ~15' square field centered on the ecliptic plane. Point sources were extracted using the technique described in 1999 by Desert et al. Two known asteroids appear in these frames, and 20 sources moving with velocities appropriate for main-belt asteroids are present. Most of the asteroids detected have flux densities less than 1 mJy, that is, between 150 and 350 times fainter than any of the asteroids observed by IRAS. These data provide the first direct measurement of the 12 μm sky-plane density for asteroids on the ecliptic equator. The median zodiacal foreground, as measured by ISOCAM during this survey, is found to be 22.1 ± 1.5 mJy pixel-1, i.e., 26.2 ± 1.7 MJy sr-1. The results presented here imply that the actual number of kilometer-sized asteroids may be higher than several recent estimates based upon observations at visual wavelengths and are in reasonable agreement with the statistical asteroid model. Using results from the observations presented here, together with three other recent population estimates, we conclude that the cumulative number of main-belt asteroids with diameters greater than 1 km is (1.2 ± 0.5) × 106.
- Published
- 2002
35. Infrared Space Observatories: How to Mitigate Zodiacal Dust Interference
- Author
-
Jeremy Kasdin, S. M. Nissanke, Sara Seager, R. Arrell, and Pini Gurfil
- Subjects
Physics ,Brightness ,Zodiacal light ,Astrophysics (astro-ph) ,Astrophysics::Instrumentation and Methods for Astrophysics ,FOS: Physical sciences ,Astronomy ,Astronomy and Astrophysics ,Astrophysics ,Terrestrial Planet Finder ,law.invention ,Telescope ,Gravitation ,Background noise ,Reduction (complexity) ,Space and Planetary Science ,law ,Trajectory ,Astrophysics::Solar and Stellar Astrophysics ,Astrophysics::Earth and Planetary Astrophysics - Abstract
(Abridged) Out-of-the-ecliptic trajectories that are beneficial to space observatories such as the Terrestrial Planet Finder and other potential mid-IR missions are introduced. These novel trajectories result in significantly reduced background noise from the zodiacal dust radiation and therefore allow a reduction in telescope collecting area and hence cost. Two types of optimal trajectories that are energetically feasible were derived using genetic algorithms. These are highly inclined non-Keplerian heliocentric orbits. The first optimal trajectory can use existing launch technology and the zodiacal brightness for this trajectory is reduced by at least 50% for 60% of the mission lifetime. The second optimal trajectory requires planned improvement in launch technology but it renders a zodiacal cloud brightness reduction by at least 70% for 82% of the mission lifetime. Heliocentric orbits at 5 AU have been discussed because the zodiacal dust concentration is extremely low there and the energy requirements to reach these trajectories are low if gravitational assists can be used. Unfortunately such orbits are impractical because of high cost, power source constraints (inability to use solar cells), communication delays, and a long travel time before data return. Additionally, the energy requirements to reach our low and high energy optimal trajectories are respectively half as much and equivalent to a direct trip to 5AU with no planetary gravitational assists., Comment: submitted to ApJ, 24 pages incl. 12 figures
- Published
- 2002
36. Radar Detectability Studies of Slow and Small Zodiacal Dust Cloud Particles. III. The Role of Sodium and the Head Echo Size on the Probability of Detection
- Author
-
Diego Janches, Robert A. Marshall, Petr Pokorný, J. D. Carrillo-Sánchez, Wuhu Feng, N. Swarnalingam, Juan Carlos Gómez-Martín, David Nesvorný, and John M. C. Plane
- Subjects
Physics ,Meteor (satellite) ,education.field_of_study ,Radar tracker ,Zodiacal light ,010504 meteorology & atmospheric sciences ,Meteoroid ,Population ,Flux ,Astronomy and Astrophysics ,Astrophysics ,01 natural sciences ,law.invention ,Space and Planetary Science ,law ,Ionization ,0103 physical sciences ,Astrophysics::Earth and Planetary Astrophysics ,Radar ,education ,010303 astronomy & astrophysics ,0105 earth and related environmental sciences ,Remote sensing - Abstract
We present a path forward on a long-standing issue concerning the flux of small and slow meteoroids, which are believed to be the dominant portion of the incoming meteoric mass flux into the Earth's atmosphere. Such a flux, which is predicted by dynamical dust models of the Zodiacal Cloud, is not evident in ground-based radar observations. For decades this was attributed to the fact that the radars used for meteor observations lack the sensitivity to detect this population, due to the small amount of ionization produced by slow-velocity meteors. Such a hypothesis has been challenged by the introduction of meteor head echo (HE) observations with High Power and Large Aperture radars, in particular the Arecibo 430 MHz radar. Janches et al. developed a probabilistic approach to estimate the detectability of meteors by these radars and initially showed that, with the current knowledge of ablation and ionization, such particles should dominate the detected rates by one to two orders of magnitude compared to the actual observations. In this paper, we include results in our model from recently published laboratory measurements, which showed that (1) the ablation of Na is less intense covering a wider altitude range; and (2) the ionization probability, βip for Na atoms in the air is up to two orders of magnitude smaller for low speeds than originally believed. By applying these results and using a somewhat smaller size of the HE radar target we offer a solution that reconciles these observations with model predictions.
- Published
- 2017
37. Detection of the Cosmic Infrared Background at 2.2 and 3.5 Microns Using DIRBE Observations
- Author
-
Erik D. Reese and Edward L. Wright
- Subjects
Physics ,L band ,COSMIC cancer database ,Zodiacal light ,Diffuse Infrared Background Experiment ,Infrared ,media_common.quotation_subject ,Astrophysics (astro-ph) ,FOS: Physical sciences ,Astronomy and Astrophysics ,Astrophysics ,Star count ,Space and Planetary Science ,Sky ,Cosmic infrared background ,media_common - Abstract
We compare data from the Diffuse InfraRed Background Experiment (DIRBE) on the Cosmic Background Explorer (COBE) satellite to the the Wainscoat et al. (1992) model of the infrared sky. The model is first compared with broadband K (2.2 microns) star counts. Its success at K gives credence to its physical approach which is extrapolated to the L band (3.5 microns). We have analyzed the histograms of the pixel by pixel intensities in the 2.2 and 3.5 micron maps from DIRBE after subtracting the zodiacal light. The shape of these histograms agrees quite well with the histogram shape predicted using the Wainscoat et al. model of the infrared sky, but the predicted histograms must be displaced by a constant intensity in order to match the data. This shift is the cosmic infrared background, which is 16.9+/-4.4 kJy/sr or 23.1+/-5.9 nW/m^2/sr at 2.2 microns, and 14.4+/-3.7 kJy/sr or 12.4+/-3.2 nW/m^2/sr at 3.5 microns., Comment: 30 pages with 10 included figures, submitted to the ApJ
- Published
- 2000
38. Detection of a Far‐Infrared Excess with DIRBE at 60 and 100 Microns
- Author
-
David J. Schlegel, Douglas P. Finkbeiner, and Marc Davis
- Subjects
Physics ,Solar System ,Zodiacal light ,Opacity ,Star formation ,media_common.quotation_subject ,Ecliptic ,Astronomy and Astrophysics ,Astrophysics ,Accretion (astrophysics) ,Galaxy ,Space and Planetary Science ,Sky ,media_common - Abstract
From analysis of the DIRBE weekly averaged sky maps, we have detected substantial flux in the 60 and 100 micron channels in excess of expected zodiacal and Galactic emission. Two methods are used to separate zodiacal light from more distant emission. Method I makes use of the time-dependence of the North-South annual variation observed at the ecliptic poles. This method is robust against errors in the inter-planetary dust (IPD) model, but does not demonstrate isotropy of the background. Method II measures the ecliptic latitude dependence of the dust over a range of ecliptic latitudes at solar elongation e=90 degrees. This allows the excess to be determined in each week of the DIRBE mission for high redundancy, but the results depend weakly on the IPD model. Both methods give consistent results at 60 and 100 microns. The observed signal is consistent with an isotropic background at the level \nu I_\nu = 28.1 +- 1.8 +- 7(syst) nW/m^2/sr at 60 microns and 24.6 +- 2.5 +- 8 nW/m^2/sr at 100 microns. The IR excess detected at 140 and 240 microns by these methods agrees with previous measurements, which are thought to be the cosmic infra-red background (CIB). The detections at 60 and 100 microns are new. While this new excess is not necessarily the CIB, we have ruled out all known sources of emission in the solar system and Galaxy. We therefore tentatively interpret this signal as the CIB and consider the implications of such energy production from the viewpoint of star formation efficiency and black hole accretion efficiency. However, the IR excess exceeds limits on the CIB derived from the inferred opacity of the IGM to observed TeV photons, thus casting doubt on this interpretation. There is currently no satisfactory explanation for the 60-100 micron excess.
- Published
- 2000
39. The Discovery of a Faint Glow of Scattered Sunlight from the Dust Trail of the Leonid Parent Comet 55P/Tempel‐Tuttle
- Author
-
Y. Fujii, Peter Jenniskens, Tadashi Mukai, K. Morishige, Masateru Ishiguro, Ryosuke Nakamura, and Sozo Yokogawa
- Subjects
Physics ,Brightness ,Zodiacal light ,Meteoroid ,Space and Planetary Science ,Sky brightness ,Comet dust ,Comet ,Interplanetary medium ,Astronomy ,Astronomy and Astrophysics ,Zenith - Abstract
A meteoric cloud is the faint glow of sunlight scattered by small meteoroids in the dust trail along the orbit of a comet as seen by an earthbound observer. While these clouds were previously only known from anecdotes of past meteor storms, we now report the detection of a meteoric cloud by modern tech niques in the direction of the dust trail of comet 55P/Tempel-Tuttle, the parent of the Leonid meteor stream. Our photometric observations, performed on Mauna Kea, Hawaii, reveal the cloud as a local enhancement in sky brightness during the Leonid shower in 1998. The radius of the trail, deduced from the spatial extent of the cloud, is approximately 0.01 AU and is consistent with the spatial extent mapped out by historic accounts of meteor storms. The brightness of the cloud is approximately D2%E3% of the background zodiacal light and cannot be explained by simple model calculations based on the zenith hourly rate and population index of the meteor stream in 1998. If the typical size of cloud particles is 10 km and the albedo is 0.1, the brightness translates into a number density of 1.2 ] 10~10 m~3. The meteoroid cloud would be the product of the whole dust trail and not only the part that was crossed in 1998. Subject headings : comets : individual (55P/Tempel-Tuttle) E dust, extinction E interplanetary medium E meteors, meteoroids
- Published
- 2000
40. Calibrating Array Detectors
- Author
-
R. G. Arendt, D. J. Fixsen, and Samuel H. Moseley
- Subjects
Physics ,Zodiacal light ,media_common.quotation_subject ,Astrophysics (astro-ph) ,Near-infrared spectroscopy ,Detector ,Astrophysics::Instrumentation and Methods for Astrophysics ,FOS: Physical sciences ,Astronomy and Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Astrophysics ,Large format ,Space and Planetary Science ,Sky brightness ,Sky ,Calibration ,Noise (video) ,Astrophysics::Galaxy Astrophysics ,Remote sensing ,media_common - Abstract
The development of sensitive large format imaging arrays for the infrared promises to provide revolutionary capabilities for space astronomy. For example, the Infrared Array Camera (IRAC) on SIRTF will use four 256 x 256 arrays to provide background limited high spatial resolution images of the sky in the 3 to 8 micron spectral region. In order to reach the performance limits possible with this generation of sensitive detectors, calibration procedures must be developed so that uncertainties in detector calibration will always be dominated by photon statistics from the dark sky as a major system noise source. In the near infrared, where the faint extragalactic sky is observed through the scattered and reemitted zodiacal light from our solar system, calibration is particularly important. Faint sources must be detected on this brighter local foreground. We present a procedure for calibrating imaging systems and analyzing such data. In our approach, by proper choice of observing strategy, information about detector parameters is encoded in the sky measurements. Proper analysis allows us to simultaneously solve for sky brightness and detector parameters, and provides accurate formal error estimates. This approach allows us to extract the calibration from the observations themselves; little or no additional information is necessary to allow full interpretation of the data. Further, this approach allows refinement and verification of detector parameters during the mission, and thus does not depend on a priori knowledge of the system or ground calibration for interpretation of images., Comment: Scheduled for ApJS, June 2000 (16 pages, 3 JPEG figures)
- Published
- 2000
41. Observations of the Trans‐Neptunian Objects 1993 SC and 1996 TL \documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \usepackage[OT2,OT1]{fontenc} \newcommand\cyr{ \renewcommand\rmdefault{wncyr} \renewcommand\sfdefault{wncyss} \renewcommand\encodingdefault{OT2} \normalfont \selectfont} \DeclareTextFontCommand{\textcyr}{\cyr} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} \landscape $_{66}$ \end{document} with theInfrared Space Observatory
- Author
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Heike Rauer, Alan Fitzsimmons, Gerhard Hahn, Nicolas Thomas, Laurent Jorda, G. Lichtenberg, S. Eggers, H. U. Keller, W.-H. Ip, and Iwan P. Williams
- Subjects
Effective radius ,Physics ,Zodiacal light ,Space and Planetary Science ,Infrared ,Asteroid ,Geometric albedo ,Position (vector) ,Ecliptic ,Astronomy ,Astronomy and Astrophysics ,Trans-Neptunian object - Abstract
Observations at 90 μm of the trans-Neptunian objects (TNOs), 1993 SC and 1996 TL66, using the Infrared Space Observatory (ISO) are reported. Five individual observations of 1993 SC were acquired giving a 2.7 σ detection (a confidence level of 99.6%). The signal level of 11.46 ± 4.24 mJy has been modeled using a standard thermal model (STM) and gives an effective radius of 164 km and a geometric albedo of 0.022. Estimated radii and albedos using the fast rotator approximation and the thermophysical model are also presented. Two individual observations of 1996 TL66 are also reported. A clear signal of 39.77 ± 11.62 mJy at 90 μm was recorded. However, the position of the signal on the detector does not correspond to the position expected. A detailed investigation has not revealed a satisfactory explanation. Assuming that ISO was mispointed and that the origin of the signal is 1996 TL66, application of the STM gives an effective radius of 316 km and a geometric albedo of 0.030. This is in good agreement with expectations based on the assumption that the surfaces of TNOs are similar to those of cometary nuclei. The results for 1996 TL66 and 1993 SC indicate that TNOs are large, spherical, and very dark objects. A main-belt asteroid, 1997 SU15, was also detected giving an effective radius of 1.13 ± 0.04 km and a geometric albedo of 0.25 ± 0.02. An estimate of the relative dependence of the zodiacal light background in the ecliptic on elongation angle at 90 μm was also determined.
- Published
- 2000
42. Thermal Infrared Images of the Remarkable Young Nearby Multiple Star HD 98800
- Author
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J. Krautter, Joshua G. Nollenberg, Robert D. Gehrz, Frank J. Low, Nathan Smith, and Terry J. Jones
- Subjects
Physics ,Stars ,Zodiacal light ,Space and Planetary Science ,Primary (astronomy) ,Star formation ,Circumstellar dust ,Astronomy ,Astronomy and Astrophysics ,Astrophysics ,Radiation ,Low Mass ,Cosmic dust - Abstract
We present thermal infrared images of the unusual multiple stellar system HD 98800, which contains two double-star systems (A and B) separated by ≈08 in the north/south direction. This system may have formed in a recent burst of star formation in a very low mass cloud in the local solar neighborhood. Our images resolve the A and B components. Both A and B emit roughly equal fluxes at 4.71 μm, where radiation is primarily photospheric. The northern component (B) is about 3.7 times brighter than the southern component (A) at 9.78 μm where the radiation is due to thermal emission from dust, showing that 78% of the circumstellar dust in the system resides around component B. The two primary components are nearly identical K5 V pre-main-sequence stars, both with very significant amounts of dust emission. The dust system around the B component may have size, temperature, and possible structure analogous to those of a primitive zodiacal cloud.
- Published
- 1999
43. TheCOBEDiffuse Infrared Background Experiment Search for the Cosmic Infrared Background. II. Model of the Interplanetary Dust Cloud
- Author
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Michael G. Hauser, N. Odegard, Robert F. Silverberg, Bryan A. Franz, William T. Reach, Samuel H. Moseley, T. Kelsall, J. L. Weiland, R. G. Arendt, E. Dwek, Edward L. Wright, and H. T. Freudenreich
- Subjects
Physics ,Brightness ,Zodiacal light ,Diffuse Infrared Background Experiment ,Infrared ,media_common.quotation_subject ,Astrophysics (astro-ph) ,Astrophysics::Instrumentation and Methods for Astrophysics ,FOS: Physical sciences ,Astronomy and Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Astrophysics ,Interplanetary dust cloud ,Space and Planetary Science ,Sky brightness ,Sky ,Cosmic infrared background ,Astrophysics::Earth and Planetary Astrophysics ,Astrophysics::Galaxy Astrophysics ,media_common - Abstract
The COBE Diffuse Infrared Background Experiment (DIRBE) was designed to search for the cosmic infrared background (CIB) radiation. Scattered light and thermal emission from the interplanetary dust (IPD) are major contributors to the diffuse sky brightness at most infrared wavelengths. Accurate removal of this zodiacal light foreground is a necessary step toward a direct measurement of the CIB. The zodiacal light foreground contribution in each of the 10 DIRBE wavelength bands ranging from 1.25 to 240 microns is distinguished by its apparent seasonal variation over the whole sky. This contribution has been extracted by fitting the brightness calculated from a parameterized physical model to the time variation of the all-sky DIRBE measurements over 10 months of observations. The model brightness is evaluated as the integral along the line of sight of the product of a source function and a three-dimensional dust density distribution function. The dust density distribution is composed of multiple components: a smooth cloud, three asteroidal dust bands, and a circumsolar ring near 1 A.U. By using a directly measurable quantity which relates only to the IPD cloud, we exclude other contributors to the sky brightness from the IPD model. Using the IPD model described here, high-quality maps of the infrared sky with the zodiacal foreground removed have been generated. Imperfections in the model reveal themselves as low-level systematic artifacts in the residual maps which correlate with components of the IPD. The most evident of these artifacts are located near the ecliptic plane in the mid-infrared, and are less than 2% of the zodiacal foreground brightness. Uncertainties associated with the model are discussed, including implications for the CIB search., Comment: 39 pages using aaspp4.sty, tables 1-4 separate files, 8 JPEG figures, 13 GIF figures. Accepted for publication in Astrophysical Journal
- Published
- 1998
44. Maps of Dust Infrared Emission for Use in Estimation of Reddening and Cosmic Microwave Background Radiation Foregrounds
- Author
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Marc Davis, David J. Schlegel, and Douglas P. Finkbeiner
- Subjects
Physics ,Zodiacal light ,Vista Variables in the Via Lactea ,Space and Planetary Science ,Spinning dust ,Hubble Deep Field ,Cosmic infrared background ,Surface brightness fluctuation ,Zone of Avoidance ,Astronomy and Astrophysics ,Astrophysics ,Planetary nebula luminosity function - Abstract
We present a full sky 100 micron map that is a reprocessed composite of the COBE/DIRBE and IRAS/ISSA maps, with the zodiacal foreground and confirmed point sources removed. Before using the ISSA maps, we remove the remaining artifacts from the IRAS scan pattern. Using the DIRBE 100 micron and 240 micron data, we have constructed a map of the dust temperature, so that the 100 micron map can be converted to a map proportional to dust column density. The result of these manipulations is a map with DIRBE-quality calibration and IRAS resolution. To generate the full sky dust maps, we must first remove zodiacal light contamination as well as a possible cosmic infrared background (CIB). This is done via a regression analysis of the 100 micron DIRBE map against the Leiden- Dwingeloo map of H_I emission, with corrections for the zodiacal light via a suitable expansion of the DIRBE 25 micron flux. For the 100 micron map, no significant CIB is detected. In the 140 micron and 240 micron maps, where the zodiacal contamination is weaker, we detect the CIB at surprisingly high flux levels of 32 \pm 13 nW/m^2/sr at 140 micron, and 17 \pm 4 nW/m^2/sr at 240 micron (95% confidence). This integrated flux is ~2 times that extrapolated from optical galaxies in the Hubble Deep Field. The primary use of these maps is likely to be as a new estimator of Galactic extinction. We demonstrate that the new maps are twice as accurate as the older Burstein-Heiles estimates in regions of low and moderate reddening. These dust maps will also be useful for estimating millimeter emission that contaminates CMBR experiments and for estimating soft X-ray absorption.
- Published
- 1998
45. Infrared Properties of Molecular Cirrus. I. Photometry of Extended Sources on [ITAL]IRAS[/ITAL] Image Products
- Author
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Lee J. Rickard and Frances Verter
- Subjects
Physics ,Zodiacal light ,media_common.quotation_subject ,Molecular cloud ,Ecliptic ,Astronomy ,Astronomy and Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Astrophysics ,Photometry (optics) ,Space and Planetary Science ,Sky ,Astrophysics::Solar and Stellar Astrophysics ,Cirrus ,Surface brightness ,Astrophysics::Galaxy Astrophysics ,media_common ,Data reduction - Abstract
We have conducted a survey of IRAS images of the high-latitude molecular cirrus clouds cataloged by Magnani, Blitz, & Mundy. This paper reports the data reduction methods used in our survey and also studies the photometric accuracy that can be achieved for faint extended sources on IRAS image products. The principal topics covered are the modeling and removal of sky backgrounds at high Galactic latitude, and as a function of ecliptic latitude; the relative accuracy of different background models and methods of background removal; the integration of source flux on background-subtracted images; the proper definition of flux error bars, their calculation, and the minimum uncertainties set by the performance of the IRAS detectors; the creation of multiple-wavelength composite images; and the creation of temperature and opacity maps. We find that most error bars quoted for IRAS fluxes in the literature are incorrect. We conclude that the limiting surface brightness to which Sky Flux Plates may be used to study faint extended sources is approximately 0.05 MJy sr-1. The photometric issues discussed herein are relevant to all IRAS image products, including Sky Flux Plates, co-added images, and the IRAS Sky Survey Atlas (ISSA). We compare the accuracy of data reduction on different products and discuss their relative advantages and disadvantages. We are particularly concerned with the accurate removal of zodiacal backgrounds near the ecliptic plane, a region known as the ISSA Reject Set.
- Published
- 1998
46. Quasi‐Stationary States of Dust Flows under Poynting‐Robertson Drag: New Analytical and Numerical Solutions
- Author
-
Leonid M. Ozernoy, Nick Gorkavyi, Tanya Taidakova, and John C. Mather
- Subjects
Physics ,Orbital elements ,Solar System ,Zodiacal light ,Astrophysics (astro-ph) ,FOS: Physical sciences ,Astronomy and Astrophysics ,Astrophysics ,Planetary system ,Interplanetary dust cloud ,Continuity equation ,Space and Planetary Science ,Drag ,Physics::Space Physics ,Astrophysics::Solar and Stellar Astrophysics ,Astrophysics::Earth and Planetary Astrophysics ,Astrophysics::Galaxy Astrophysics ,Stationary state - Abstract
The effect of solar or stellar radiation on dust particles' trajectories (the Poynting-Robertson drag) has been studied by a number of authors and applied to interplanetary dust dynamics in numerical computations. Meanwhile some important features of dust flows can be studied analytically by implementing our novel hydrodynamical approach to use the continuity equation written in the particle's orbital elements as coordinates (Gor'kavyi, Ozernoy, & Mather 1997). By employing this approach and integrating the continuity equation, we are able to find two integrals of motion when the Poynting-Robertson drag dominates the dissipative forces in the dust flow. These integrals of motion enable us to explore basic characteristics of dust flows from any sources in the Solar system (such as asteroids, comets, Kuiper belt, etc.) or in another planetary system. In particular, we have reproduced the classical solution $n(r)\propto r^{-1}$ that approximately represents the overall distribution of dust in the Solar system. We have also investigated various factors that could be responsible for the deviations of the power law index in $n(r)\propto r^{\delta}$ from $\delta=-1$, including the influences of the orbital characteristics of dust sources, the evaporation of dust particles, as well as mixtures of dust particles of both asteroidal and cometary origin. We have calculated the masses and number densities of asteroidal and cometary components of the zodiacal cloud at different distances from the Sun., Comment: Accepted for publication in ApJ, v. 488, Oct. 10, 1997; 22 pages, Latex, 12 Postscript figures
- Published
- 1997
47. A Three‐dimensional Decomposition of the Infrared Emission from Dust in the Milky Way
- Author
-
M. G. Hauser, Janet L. Weiland, N. Odegard, R. G. Arendt, T. Kelsall, T. J. Sodroski, and E. Dwek
- Subjects
Physics ,Spiral galaxy ,Zodiacal light ,Astrophysics::High Energy Astrophysical Phenomena ,Milky Way ,Astronomy ,Astronomy and Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Astrophysics ,Galactic plane ,Galaxy ,Interstellar medium ,Space and Planetary Science ,Astrophysics::Earth and Planetary Astrophysics ,Disc ,Astrophysics::Galaxy Astrophysics ,Cosmic dust - Abstract
We have constructed a three-dimensional model of the Galactic large-scale infrared emission from dust associated with the molecular neutral atomic (H I), and extended low-density cm~3) (H 2 ), (n e D 1E100 ionized (H II) gas phases of the interstellar medium. The model incorporates a three-dimensional map of the molecular and neutral atomic hydrogen gas distributions, derived from available 12CO and H I surveys by using the radial velocity information in the spectral lines as a distance indicator, and available 5 and 19 GHz radio continuum surveys to trace the column density of ionized gas. We use the model to decompose the Di†use Infrared Background Experiment (DIRBE) 12E240 km obserCOBE5 vations of the Galactic plane region ( o b o „ 5i), from which the zodiacal light and stellar emission have been subtracted, into distinct emission components associated with each gas phase within selected ranges of Galactocentric distance. An interstellar dust model is ‐tted to the resulting infrared spectra to derive the following quantities within each Galactocentric distance interval: (1) the abundance and equilibrium temperature of the large dust grain component within each gas phase; (2) estimates of the abundance of very small (\200 transiently heated dust grains and polycyclic aromatic hydrocarbon (PAH) mol”) ecules; and (3) constraints on various model parameters, such as the energy density of the ambient interstellar radiation ‐eld, which heats the dust within the H I gas phase. Our results show steep negative Galactocentric gradients in the equilibrium temperature of the large dust grain component within the H I, and H II gas phases, the GalaxyIs ambient interstellar radiH 2 , ation ‐eld, and the dust-to-gas mass ratio for each gas phase. The intensity of the ambient interstellar radiation ‐eld increases by a factor of D3 between the solar circle (8.5 kpc) and the molecular ring at a Galactocentric distance of D5 kpc. The dust abundance gradient of ([0.05 ^ 0.03) dex kpc~1 is equivalent, within the uncertainties, to the metallicity gradient in the Galactic disk. The derived emission spectra are consistent with a model in which very small transiently heated dust grains and PAHs are abundant and the dominant contributors to the mid-infrared (5 km \j\ 40 km) luminosity from a Galactocentric distance of 2 kpc out to a Galactocentric distance of at least 12 kpc, and indicate that the relative abundance of the PAHs is signi‐cantly higher in the outer region of the Galactic disk than inside the solar circle. We combine the results of our decomposition algorithm with the results of a study of optical extinction at high Galactic latitude to derive the radial distribution of optical opacity in the Galactic disk and ‐nd that our Galaxy would be e†ectively transparent Galaxy) \ 0.2 mag] to an external obser[A B (total ver viewing it at a low inclination (i \ 30i). All of the Galactic infrared emission observed by the DIRBE can be accounted for by dust associated with gas that is detected by current radio surveys, refuting the recent suggestion that a large fraction of the dynamically inferred hidden mass in spiral galaxies may be due to unseen gas and stars in the disk of the galaxies. Subject headings: di†use radiation E dust, extinction E Galaxy: structure E infrared: ISM: continuum E ISM: abundances E ISM: molecules
- Published
- 1997
48. An Imaging Nulling Interferometer to Study Extrasolar Planets
- Author
-
James Roger P. Angel and Neville J. Woolf
- Subjects
Physics ,Zodiacal light ,Aperture synthesis ,Astrophysics::Instrumentation and Methods for Astrophysics ,Astronomy ,Astronomy and Astrophysics ,Astrophysics ,Planetary system ,Exoplanet ,Jupiter ,Interferometry ,Space and Planetary Science ,Planet ,Astrophysics::Earth and Planetary Astrophysics ,Astrophysics::Galaxy Astrophysics ,Nuller - Abstract
Interferometric techniques offer two advantages for the detection and analysis of thermal radiation from planets: destructive interference to strongly suppress the stellar emission, and the possibility of high-resolution imaging to resolve planets and distinguish them from dust emission. This paper presents a new interferometric configuration in which the conflicting requirements for these goals are reconciled. It realizes a very strong, broad interference null, so high-resolution fringes can be used while maintaining good suppression of the stellar disk. Complex phase measurement is precluded by the need for destructive interference, but we find that a cross-correlation technique analogous to aperture synthesis can recover true images. When operated 5 AU from the Sun to escape background emission from local zodiacal dust, the interferometer's sensitivity will be limited fundamentally by noise in the photon flux from warm zodiacal dust in the planetary system under observation. In order to scale the interferometer for adequate sensitivity, the 10 μm emission from such dust could be determined early on by a ground-based interferometer. If stars at 10 pc distance have zodiacal clouds like our own, a 50 m long space interferometer with four 1 m elements should see individual planets like the Earth in images taken over 10 hours. Simultaneous infrared spectra of planets like Earth, Venus, Jupiter, and Saturn could be obtained during a 3 month integration, with the sensitivity to detect carbon dioxide, water, and ozone at the levels seen in Earth's spectrum.
- Published
- 1997
49. An Estimation of the Interstellar Contribution to the Zodiacal Thermal Emission
- Author
-
Stanley F. Dermott, Bo Å. S. Gustafson, and K. Grogan
- Subjects
Physics ,Zodiacal light ,Extinction (astronomy) ,Ecliptic ,Astronomy ,Interplanetary medium ,Astronomy and Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Astrophysics ,Galaxy ,Latitude ,Radiation pressure ,Space and Planetary Science ,Physics::Space Physics ,Astrophysics::Solar and Stellar Astrophysics ,Astrophysics::Earth and Planetary Astrophysics ,Astrophysics::Galaxy Astrophysics ,Cosmic dust - Abstract
Impact data from the Ulysses dust detector at 5 AU from the Sun have been interpreted as a flux of submicron interstellar dust particles arriving from ecliptic longitude 252° and ecliptic latitude 25. By following the motions of these particles under the influence of solar gravity, radiation pressure, and electromagnetic forces, we derive a model of the thermal emission from the resultant particle cloud. Since the distributions of the particles are time variable depending on the solar cycle, calculations are performed for the years 1984 and 1990, corresponding, respectively, to the times of the IRAS and COBE observations. We also illustrate how the distributions vary with particle size (or, at a more basic level β, the ratio of the radiation pressure to gravitational force) by presenting results for three different particle sizes. Patches of emission from our test cloud reach peak levels of 0.1 MJy sr–1 in the 12 μm wave band. This represents 10% of the average brightness asymmetry around the sky between the trailing/leading telescope pointing directions seen in the IRAS and COBE data sets. Some of these patches occur at high ecliptic latitudes where the contribution from the Galaxy is negligible and emission from the smooth zodiacal background is low compared to that at low ecliptic latitudes. A strong seasonal variation in the predicted interstellar emission trailing/leading asymmetry is the most obvious signature of the interstellar source, and, in addition, the time variability of the emission will produce different features in the IRAS and COBE data sets and in any subsequent infrared mission. For these reasons, a search of the data for the predicted signatures is certainly justifiable.
- Published
- 1996
50. COSMIC INFRARED BACKGROUND FLUCTUATIONS AND ZODIACAL LIGHT
- Author
-
Samuel H. Moseley, A. Kashlinsky, Richard G. Arendt, and John C. Mather
- Subjects
Physics ,Cosmology and Nongalactic Astrophysics (astro-ph.CO) ,Zodiacal light ,Infrared ,Astrophysics::Instrumentation and Methods for Astrophysics ,Ecliptic ,FOS: Physical sciences ,Spectral density ,Astronomy and Astrophysics ,White noise ,Astrophysics ,01 natural sciences ,Physics::Popular Physics ,Wavelength ,Space and Planetary Science ,Cosmic infrared background ,0103 physical sciences ,Angular resolution ,Astrophysics::Earth and Planetary Astrophysics ,010306 general physics ,010303 astronomy & astrophysics ,Astrophysics - Cosmology and Nongalactic Astrophysics - Abstract
We have performed a specific observational test to measure the effect that the zodiacal light can have on measurements of the spatial fluctuations of the near-IR background. Previous estimates of possible fluctuations caused by zodiacal light have often been extrapolated from observations of the thermal emission at longer wavelengths and low angular resolution, or from IRAC observations of high latitude fields where zodiacal light is faint and not strongly varying with time. The new observations analyzed here target the COSMOS field, at low ecliptic latitude where the zodiacal light intensity varies by factors of $\sim2$ over the range of solar elongations at which the field can be observed. We find that the white noise component of the spatial power spectrum of the background is correlated with the modeled zodiacal light intensity. Roughly half of the measured white noise is correlated with the zodiacal light, but a more detailed interpretation of the white noise is hampered by systematic uncertainties that are evident in the zodiacal light model. At large angular scales ($\gtrsim100"$) where excess power above the white noise is observed, we find no correlation of the power with the modeled intensity of the zodiacal light. This test clearly indicates that the large scale power in the infrared background is not being caused by the zodiacal light., Comment: 17 pp. Accepted for publication in the ApJ
- Published
- 2016
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