The Experts below are selected from a list of 26550 Experts worldwide ranked by ideXlab platform
Erik J Tollerud - One of the best experts on this subject based on the ideXlab platform.
-
type iin supernovae at z 2 from Archival Data
Nature, 2009Co-Authors: Jeff Cooke, M Sullivan, Elizabeth J Barton, Ray Carlberg, Erik J Tollerud, James Bullock, A GalyamAbstract:Supernovae have been confirmed to redshift z ~ 1.7 for type Ia (thermonuclear detonation of a white dwarf) and to z ~ 0.7 for type II (collapse of the core of the star). The subclass type IIn supernovae are luminous core-collapse explosions of massive stars and, unlike other types, are very bright in the ultraviolet, which should enable them to be found optically at redshifts z ~ 2 and higher. In addition, the interaction of the ejecta with circumstellar material creates strong, long-lived emission lines that allow spectroscopic confirmation of many events of this type at z ~ 2 for 3 - 5 years after explosion. Here we report three spectroscopically confirmed type IIn supernovae, at redshifts z = 0.808, 2.013 and 2.357, detected in Archival Data using a method designed to exploit these properties at z ~ 2. Type IIn supernovae directly probe the formation of massive stars at high redshift. The number found to date is consistent with the expectations of a locally measured stellar initial mass function, but not with an evolving initial mass function proposed to explain independent observations at low and high redshift.
-
type iin supernovae at redshift z thinsp ap thinsp 2 from Archival Data
Nature, 2009Co-Authors: Jeff Cooke, M Sullivan, Elizabeth J Barton, Ray Carlberg, A Galyam, James Bullock, Erik J TollerudAbstract:Supernovae have been confirmed to redshift z 1.7 (refs 1, 2) for type Ia (thermonuclear detonation of a white dwarf) and to z 0.7 (refs 1, 3–5) for type II (collapse of the core of the star). The subclass type IIn (ref. 6) supernovae are luminous7, 8, 9 core-collapse explosions of massive stars8, 9, 10, 11 and, unlike other types, are very bright in the ultraviolet12, 13, 14, 15, which should enable them to be found optically at redshifts z 2 and higher14, 16. In addition, the interaction of the ejecta with circumstellar material creates strong, long-lived emission lines that allow spectroscopic confirmation of many events of this type at z 2 for 3–5 years after explosion (ref. 14). Here we report three spectroscopically confirmed type IIn supernovae, at redshifts z = 0.808, 2.013 and 2.357, detected in Archival Data using a method14 designed to exploit these properties at z 2. Type IIn supernovae directly probe the formation of massive stars at high redshift. The number found to date is consistent with the expectations of a locally measured17 stellar initial mass function, but not with an evolving initial mass function proposed18, 19, 20 to explain independent observations at low and high redshift.
-
Type IIn supernovae at redshift z|[thinsp]||[ap]||[thinsp]|2 from Archival Data
Nature, 2009Co-Authors: Jeff Cooke, M Sullivan, Elizabeth J Barton, Ray Carlberg, James Bullock, Erik J TollerudAbstract:Supernovae have been confirmed to redshift z 1.7 (refs 1, 2) for type Ia (thermonuclear detonation of a white dwarf) and to z 0.7 (refs 1, 3–5) for type II (collapse of the core of the star). The subclass type IIn (ref. 6) supernovae are luminous7, 8, 9 core-collapse explosions of massive stars8, 9, 10, 11 and, unlike other types, are very bright in the ultraviolet12, 13, 14, 15, which should enable them to be found optically at redshifts z 2 and higher14, 16. In addition, the interaction of the ejecta with circumstellar material creates strong, long-lived emission lines that allow spectroscopic confirmation of many events of this type at z 2 for 3–5 years after explosion (ref. 14). Here we report three spectroscopically confirmed type IIn supernovae, at redshifts z = 0.808, 2.013 and 2.357, detected in Archival Data using a method14 designed to exploit these properties at z 2. Type IIn supernovae directly probe the formation of massive stars at high redshift. The number found to date is consistent with the expectations of a locally measured17 stellar initial mass function, but not with an evolving initial mass function proposed18, 19, 20 to explain independent observations at low and high redshift.
-
type iin supernovae at redshift z 2 from Archival Data
Nature, 2009Co-Authors: Jeff Cooke, M Sullivan, Elizabeth J Barton, James S Bullock, Ray Carlberg, A Galyam, Erik J TollerudAbstract:Supernovae provide valuable opportunities to study galactic processes from the local Universe to large distances, but their properties and the sensitivities of current telescopes make the detection of high-redshift examples extremely difficult. Previous searches have revealed core-collapse (type II) supernovae to z ≈ 0.7 and thermonuclear (type Ia) to z ≈1.5. Now by exploiting the exceptional properties of sub-class type IIn core-collapse supernovae — including extreme brightness in the ultraviolet and bright, long-lived emission lines — Cooke et al. report the discovery in Archival Data of three previously unknown supernovae at redshifts z = 0.808, 2.013 and 2.357. The study of objects with redshifts z > 2 provides a window on the Universe at a time shortly after the formation of the first stars. Type IIn supernovae are luminous core-collapse explosions of massive stars that, unlike other types, are very bright in the ultraviolet and have strong, long-lived emission lines that should enable detection at redshift z ≈ 2. Here, three spectroscopically confirmed type IIn supernovae are reported at redshifts z = 0.808, 2.013 and 2.357, detected in Archival Data. Supernovae have been confirmed to redshift z ≈ 1.7 (refs 1, 2) for type Ia (thermonuclear detonation of a white dwarf) and to z ≈ 0.7 (refs 1, 3–5) for type II (collapse of the core of the star). The subclass type IIn (ref. 6) supernovae are luminous7,8,9 core-collapse explosions of massive stars8,9,10,11 and, unlike other types, are very bright in the ultraviolet12,13,14,15, which should enable them to be found optically at redshifts z ≈ 2 and higher14,16. In addition, the interaction of the ejecta with circumstellar material creates strong, long-lived emission lines that allow spectroscopic confirmation of many events of this type at z ≈ 2 for 3–5 years after explosion (ref. 14). Here we report three spectroscopically confirmed type IIn supernovae, at redshifts z = 0.808, 2.013 and 2.357, detected in Archival Data using a method14 designed to exploit these properties at z ≈ 2. Type IIn supernovae directly probe the formation of massive stars at high redshift. The number found to date is consistent with the expectations of a locally measured17 stellar initial mass function, but not with an evolving initial mass function proposed18,19,20 to explain independent observations at low and high redshift.
A Galyam - One of the best experts on this subject based on the ideXlab platform.
-
a single sub kilometre kuiper belt object from a stellar occultation in Archival Data
Nature, 2009Co-Authors: A Galyam, Hilke E. Schlichting, Eran O. Ofek, M. Wenz, Ramazan Sari, Mario Livio, Edmund P. Nelan, Shay ZuckerAbstract:Kuiper belt objects occupy a region of the Solar System beyond the orbit of Neptune. Many — including the dwarf planets Pluto, Haumea and Makemake — are more than 100 km in diameter. At the opposite end of the scale, sub-kilometre-sized objects cannot be observed directly. But they should be detectable as occultations of background stars and one such detection is now reported. A survey of Archival Data reveals an occultation by a body with a radius of about 500 metres at a distance of 45 astronomical units (Neptune orbits at about 30 AU) from the Sun. The fact that just one event was found in the survey suggests a deficit of sub-kilometre bodies, compared to that expected from extrapolation of the population of '50-km' bodies: this may mean that the smaller Kuiper belt objects are gradually disappearing as they collide with one another. The Kuiper belt is a remnant of the primordial Solar System. Small, sub-kilometre-sized, Kuiper belt objects elude direct detection, but the signature of their occultations of background stars should be detectable. Analysis of Archival Data now reveals an occultation by a body with an approximately 500-metre radius at a distance of 45 astronomical units. The detection of only one event reveals a deficit of sub-kilometre-sized Kuiper belt objects and implies that these small bodies are undergoing collisional erosion. The Kuiper belt is a remnant of the primordial Solar System. Measurements of its size distribution constrain its accretion and collisional history, and the importance of material strength of Kuiper belt objects1,2,3,4. Small, sub-kilometre-sized, Kuiper belt objects elude direct detection, but the signature of their occultations of background stars should be detectable5,6,7,8,9. Observations at both optical10 and X-ray11 wavelengths claim to have detected such occultations, but their implied abundances are inconsistent with each other and far exceed theoretical expectations. Here we report an analysis of Archival Data that reveals an occultation by a body with an approximately 500-metre radius at a distance of 45 astronomical units. The probability of this event arising from random statistical fluctuations within our Data set is about two per cent. Our survey yields a surface density of Kuiper belt objects with radii exceeding 250 metres of , ruling out inferred surface densities from previous claimed detections by more than 5σ. The detection of only one event reveals a deficit of sub-kilometre-sized Kuiper belt objects compared to a population extrapolated from objects with radii exceeding 50 kilometres. This implies that sub-kilometre-sized objects are undergoing collisional erosion, just like debris disks observed around other stars.
-
type iin supernovae at z 2 from Archival Data
Nature, 2009Co-Authors: Jeff Cooke, M Sullivan, Elizabeth J Barton, Ray Carlberg, Erik J Tollerud, James Bullock, A GalyamAbstract:Supernovae have been confirmed to redshift z ~ 1.7 for type Ia (thermonuclear detonation of a white dwarf) and to z ~ 0.7 for type II (collapse of the core of the star). The subclass type IIn supernovae are luminous core-collapse explosions of massive stars and, unlike other types, are very bright in the ultraviolet, which should enable them to be found optically at redshifts z ~ 2 and higher. In addition, the interaction of the ejecta with circumstellar material creates strong, long-lived emission lines that allow spectroscopic confirmation of many events of this type at z ~ 2 for 3 - 5 years after explosion. Here we report three spectroscopically confirmed type IIn supernovae, at redshifts z = 0.808, 2.013 and 2.357, detected in Archival Data using a method designed to exploit these properties at z ~ 2. Type IIn supernovae directly probe the formation of massive stars at high redshift. The number found to date is consistent with the expectations of a locally measured stellar initial mass function, but not with an evolving initial mass function proposed to explain independent observations at low and high redshift.
-
type iin supernovae at redshift z thinsp ap thinsp 2 from Archival Data
Nature, 2009Co-Authors: Jeff Cooke, M Sullivan, Elizabeth J Barton, Ray Carlberg, A Galyam, James Bullock, Erik J TollerudAbstract:Supernovae have been confirmed to redshift z 1.7 (refs 1, 2) for type Ia (thermonuclear detonation of a white dwarf) and to z 0.7 (refs 1, 3–5) for type II (collapse of the core of the star). The subclass type IIn (ref. 6) supernovae are luminous7, 8, 9 core-collapse explosions of massive stars8, 9, 10, 11 and, unlike other types, are very bright in the ultraviolet12, 13, 14, 15, which should enable them to be found optically at redshifts z 2 and higher14, 16. In addition, the interaction of the ejecta with circumstellar material creates strong, long-lived emission lines that allow spectroscopic confirmation of many events of this type at z 2 for 3–5 years after explosion (ref. 14). Here we report three spectroscopically confirmed type IIn supernovae, at redshifts z = 0.808, 2.013 and 2.357, detected in Archival Data using a method14 designed to exploit these properties at z 2. Type IIn supernovae directly probe the formation of massive stars at high redshift. The number found to date is consistent with the expectations of a locally measured17 stellar initial mass function, but not with an evolving initial mass function proposed18, 19, 20 to explain independent observations at low and high redshift.
-
type iin supernovae at redshift z 2 from Archival Data
Nature, 2009Co-Authors: Jeff Cooke, M Sullivan, Elizabeth J Barton, James S Bullock, Ray Carlberg, A Galyam, Erik J TollerudAbstract:Supernovae provide valuable opportunities to study galactic processes from the local Universe to large distances, but their properties and the sensitivities of current telescopes make the detection of high-redshift examples extremely difficult. Previous searches have revealed core-collapse (type II) supernovae to z ≈ 0.7 and thermonuclear (type Ia) to z ≈1.5. Now by exploiting the exceptional properties of sub-class type IIn core-collapse supernovae — including extreme brightness in the ultraviolet and bright, long-lived emission lines — Cooke et al. report the discovery in Archival Data of three previously unknown supernovae at redshifts z = 0.808, 2.013 and 2.357. The study of objects with redshifts z > 2 provides a window on the Universe at a time shortly after the formation of the first stars. Type IIn supernovae are luminous core-collapse explosions of massive stars that, unlike other types, are very bright in the ultraviolet and have strong, long-lived emission lines that should enable detection at redshift z ≈ 2. Here, three spectroscopically confirmed type IIn supernovae are reported at redshifts z = 0.808, 2.013 and 2.357, detected in Archival Data. Supernovae have been confirmed to redshift z ≈ 1.7 (refs 1, 2) for type Ia (thermonuclear detonation of a white dwarf) and to z ≈ 0.7 (refs 1, 3–5) for type II (collapse of the core of the star). The subclass type IIn (ref. 6) supernovae are luminous7,8,9 core-collapse explosions of massive stars8,9,10,11 and, unlike other types, are very bright in the ultraviolet12,13,14,15, which should enable them to be found optically at redshifts z ≈ 2 and higher14,16. In addition, the interaction of the ejecta with circumstellar material creates strong, long-lived emission lines that allow spectroscopic confirmation of many events of this type at z ≈ 2 for 3–5 years after explosion (ref. 14). Here we report three spectroscopically confirmed type IIn supernovae, at redshifts z = 0.808, 2.013 and 2.357, detected in Archival Data using a method14 designed to exploit these properties at z ≈ 2. Type IIn supernovae directly probe the formation of massive stars at high redshift. The number found to date is consistent with the expectations of a locally measured17 stellar initial mass function, but not with an evolving initial mass function proposed18,19,20 to explain independent observations at low and high redshift.
Jeff Cooke - One of the best experts on this subject based on the ideXlab platform.
-
type iin supernovae at z 2 from Archival Data
Nature, 2009Co-Authors: Jeff Cooke, M Sullivan, Elizabeth J Barton, Ray Carlberg, Erik J Tollerud, James Bullock, A GalyamAbstract:Supernovae have been confirmed to redshift z ~ 1.7 for type Ia (thermonuclear detonation of a white dwarf) and to z ~ 0.7 for type II (collapse of the core of the star). The subclass type IIn supernovae are luminous core-collapse explosions of massive stars and, unlike other types, are very bright in the ultraviolet, which should enable them to be found optically at redshifts z ~ 2 and higher. In addition, the interaction of the ejecta with circumstellar material creates strong, long-lived emission lines that allow spectroscopic confirmation of many events of this type at z ~ 2 for 3 - 5 years after explosion. Here we report three spectroscopically confirmed type IIn supernovae, at redshifts z = 0.808, 2.013 and 2.357, detected in Archival Data using a method designed to exploit these properties at z ~ 2. Type IIn supernovae directly probe the formation of massive stars at high redshift. The number found to date is consistent with the expectations of a locally measured stellar initial mass function, but not with an evolving initial mass function proposed to explain independent observations at low and high redshift.
-
type iin supernovae at redshift z thinsp ap thinsp 2 from Archival Data
Nature, 2009Co-Authors: Jeff Cooke, M Sullivan, Elizabeth J Barton, Ray Carlberg, A Galyam, James Bullock, Erik J TollerudAbstract:Supernovae have been confirmed to redshift z 1.7 (refs 1, 2) for type Ia (thermonuclear detonation of a white dwarf) and to z 0.7 (refs 1, 3–5) for type II (collapse of the core of the star). The subclass type IIn (ref. 6) supernovae are luminous7, 8, 9 core-collapse explosions of massive stars8, 9, 10, 11 and, unlike other types, are very bright in the ultraviolet12, 13, 14, 15, which should enable them to be found optically at redshifts z 2 and higher14, 16. In addition, the interaction of the ejecta with circumstellar material creates strong, long-lived emission lines that allow spectroscopic confirmation of many events of this type at z 2 for 3–5 years after explosion (ref. 14). Here we report three spectroscopically confirmed type IIn supernovae, at redshifts z = 0.808, 2.013 and 2.357, detected in Archival Data using a method14 designed to exploit these properties at z 2. Type IIn supernovae directly probe the formation of massive stars at high redshift. The number found to date is consistent with the expectations of a locally measured17 stellar initial mass function, but not with an evolving initial mass function proposed18, 19, 20 to explain independent observations at low and high redshift.
-
Type IIn supernovae at redshift z|[thinsp]||[ap]||[thinsp]|2 from Archival Data
Nature, 2009Co-Authors: Jeff Cooke, M Sullivan, Elizabeth J Barton, Ray Carlberg, James Bullock, Erik J TollerudAbstract:Supernovae have been confirmed to redshift z 1.7 (refs 1, 2) for type Ia (thermonuclear detonation of a white dwarf) and to z 0.7 (refs 1, 3–5) for type II (collapse of the core of the star). The subclass type IIn (ref. 6) supernovae are luminous7, 8, 9 core-collapse explosions of massive stars8, 9, 10, 11 and, unlike other types, are very bright in the ultraviolet12, 13, 14, 15, which should enable them to be found optically at redshifts z 2 and higher14, 16. In addition, the interaction of the ejecta with circumstellar material creates strong, long-lived emission lines that allow spectroscopic confirmation of many events of this type at z 2 for 3–5 years after explosion (ref. 14). Here we report three spectroscopically confirmed type IIn supernovae, at redshifts z = 0.808, 2.013 and 2.357, detected in Archival Data using a method14 designed to exploit these properties at z 2. Type IIn supernovae directly probe the formation of massive stars at high redshift. The number found to date is consistent with the expectations of a locally measured17 stellar initial mass function, but not with an evolving initial mass function proposed18, 19, 20 to explain independent observations at low and high redshift.
-
type iin supernovae at redshift z 2 from Archival Data
Nature, 2009Co-Authors: Jeff Cooke, M Sullivan, Elizabeth J Barton, James S Bullock, Ray Carlberg, A Galyam, Erik J TollerudAbstract:Supernovae provide valuable opportunities to study galactic processes from the local Universe to large distances, but their properties and the sensitivities of current telescopes make the detection of high-redshift examples extremely difficult. Previous searches have revealed core-collapse (type II) supernovae to z ≈ 0.7 and thermonuclear (type Ia) to z ≈1.5. Now by exploiting the exceptional properties of sub-class type IIn core-collapse supernovae — including extreme brightness in the ultraviolet and bright, long-lived emission lines — Cooke et al. report the discovery in Archival Data of three previously unknown supernovae at redshifts z = 0.808, 2.013 and 2.357. The study of objects with redshifts z > 2 provides a window on the Universe at a time shortly after the formation of the first stars. Type IIn supernovae are luminous core-collapse explosions of massive stars that, unlike other types, are very bright in the ultraviolet and have strong, long-lived emission lines that should enable detection at redshift z ≈ 2. Here, three spectroscopically confirmed type IIn supernovae are reported at redshifts z = 0.808, 2.013 and 2.357, detected in Archival Data. Supernovae have been confirmed to redshift z ≈ 1.7 (refs 1, 2) for type Ia (thermonuclear detonation of a white dwarf) and to z ≈ 0.7 (refs 1, 3–5) for type II (collapse of the core of the star). The subclass type IIn (ref. 6) supernovae are luminous7,8,9 core-collapse explosions of massive stars8,9,10,11 and, unlike other types, are very bright in the ultraviolet12,13,14,15, which should enable them to be found optically at redshifts z ≈ 2 and higher14,16. In addition, the interaction of the ejecta with circumstellar material creates strong, long-lived emission lines that allow spectroscopic confirmation of many events of this type at z ≈ 2 for 3–5 years after explosion (ref. 14). Here we report three spectroscopically confirmed type IIn supernovae, at redshifts z = 0.808, 2.013 and 2.357, detected in Archival Data using a method14 designed to exploit these properties at z ≈ 2. Type IIn supernovae directly probe the formation of massive stars at high redshift. The number found to date is consistent with the expectations of a locally measured17 stellar initial mass function, but not with an evolving initial mass function proposed18,19,20 to explain independent observations at low and high redshift.
John D Anderson - One of the best experts on this subject based on the ideXlab platform.
-
rhea s gravitational field and interior structure inferred from Archival Data files of the 2005 cassini flyby
Physics of the Earth and Planetary Interiors, 2010Co-Authors: John D Anderson, Gerald SchubertAbstract:Abstract There are three published gravitational fields for Rhea, and they all differ significantly. All three published fields fit the Data equally well, although not to the noise level. There are obvious trends in the Doppler residuals. However, by restricting the Data in the fit to a shorter interval surrounding the closest approach to Rhea, an unbiased estimate for Rhea’s quadrupole gravitational field is obtained. This paper also investigates the effects of thermal emission, which are shown to be quite important and may explain part of the discrepancy between this study and previous works. With this approach, and under the assumption that Rhea is in hydrostatic equilibrium (HE), our earlier conclusions about Rhea’s internal structure are confirmed. Rhea is an undifferentiated satellite made up of about 25% rock-metal and 75% water ice by mass. The best-fit value of the quadrupole gravitational coefficient C 22 from the present analysis is ( 267.6 ± 4.9 ) × 1 0 − 6 . Further, any assertions that Rhea is not in HE are not supported by the Data, and only an additional highly inclined flyby to Rhea’s equator could resolve this issue. Provided Rhea were not in HE, no useful constraint on Rhea’s interior structure could be imposed. Non-HE contributions to the first-order deviations from sphericity considered here are not readily available.
-
Rhea's gravitational field and interior structure inferred from Archival Data files of the 2005 Cassini flyby
Physics of the Earth and Planetary Interiors, 2010Co-Authors: John D Anderson, Gunnar SchubertAbstract:There are three published gravitational fields for Rhea, and they all differ significantly. All three published fields fit the Data equally well, although not to the noise level. There are obvious trends in the Doppler residuals. However, by restricting the Data in the fit to a shorter interval surrounding the closest approach to Rhea, an unbiased estimate for Rhea's quadrupole gravitational field is obtained. This paper also investigates the effects of thermal emission, which are shown to be quite important and may explain part of the discrepancy between this study and previous works. With this approach, and under the assumption that Rhea is in hydrostatic equilibrium (HE), our earlier conclusions about Rhea's internal structure are confirmed. Rhea is an undifferentiated satellite made up of about 25% rock-metal and 75% water ice by mass. The best-fit value of the quadrupole gravitational coefficient C22 from the present analysis is (267.6 ?? 4.9) ?? 1 0- 6. Further, any assertions that Rhea is not in HE are not supported by the Data, and only an additional highly inclined flyby to Rhea's equator could resolve this issue. Provided Rhea were not in HE, no useful constraint on Rhea's interior structure could be imposed. Non-HE contributions to the first-order deviations from sphericity considered here are not readily available. ?? 2009 Elsevier B.V. All rights reserved.
Hilke E. Schlichting - One of the best experts on this subject based on the ideXlab platform.
-
Detecting a small Kuiper Belt object using Archival Data of HST's Fine Guidance Sensor
Proceedings of High Time Resolution Astrophysics (HTRA) IV - The Era of Extremely Large Telescopes — PoS(HTRA-IV), 2011Co-Authors: Shay Zucker, Hilke E. Schlichting, Eran O. Ofek, M. Wenz, Mario Livio, Re'em Sari, Edmund P. NelanAbstract:The Kuiper Belt is a remnant of the primordial Solar System. Measurements of its size distribution constrain its accretion and collisional history, and the importance of material strength of Kuiper Belt objects. Small, sub-kilometer-sized, Kuiper Belt objects elude direct detection, but the signature of their occultations of background stars should be detectable. Such an occultation event lasts typically a fraction of a second, thus making it a classical high time-resolution observation. Here we report an analysis of Archival Data of HST’s Fine Guidance Sensors (FGS), that reveals an occultation by such a small object. The detection introduces the FGS as a valuable HTRA instrument. We discuss the statistical aspects regarding the validation of the detection claim, and its physical implications.
-
A single sub-kilometre Kuiper belt object from a stellar occultation in Archival Data
Nature, 2009Co-Authors: Hilke E. Schlichting, Eran O. Ofek, M. Wenz, Ramazan Sari, Mario Livio, Edmund P. Nelan, Shay ZuckerAbstract:The Kuiper belt is a remnant of the primordial Solar System. Small, sub-kilometre-sized, Kuiper belt objects elude direct detection, but the signature of their occultations of background stars should be detectable. Analysis of Archival Data now reveals an occultation by a body with an approximately 500-metre radius at a distance of 45 astronomical units. The detection of only one event reveals a deficit of sub-kilometre-sized Kuiper belt objects and implies that these small bodies are undergoing collisional erosion.
-
a single sub kilometre kuiper belt object from a stellar occultation in Archival Data
Nature, 2009Co-Authors: A Galyam, Hilke E. Schlichting, Eran O. Ofek, M. Wenz, Ramazan Sari, Mario Livio, Edmund P. Nelan, Shay ZuckerAbstract:Kuiper belt objects occupy a region of the Solar System beyond the orbit of Neptune. Many — including the dwarf planets Pluto, Haumea and Makemake — are more than 100 km in diameter. At the opposite end of the scale, sub-kilometre-sized objects cannot be observed directly. But they should be detectable as occultations of background stars and one such detection is now reported. A survey of Archival Data reveals an occultation by a body with a radius of about 500 metres at a distance of 45 astronomical units (Neptune orbits at about 30 AU) from the Sun. The fact that just one event was found in the survey suggests a deficit of sub-kilometre bodies, compared to that expected from extrapolation of the population of '50-km' bodies: this may mean that the smaller Kuiper belt objects are gradually disappearing as they collide with one another. The Kuiper belt is a remnant of the primordial Solar System. Small, sub-kilometre-sized, Kuiper belt objects elude direct detection, but the signature of their occultations of background stars should be detectable. Analysis of Archival Data now reveals an occultation by a body with an approximately 500-metre radius at a distance of 45 astronomical units. The detection of only one event reveals a deficit of sub-kilometre-sized Kuiper belt objects and implies that these small bodies are undergoing collisional erosion. The Kuiper belt is a remnant of the primordial Solar System. Measurements of its size distribution constrain its accretion and collisional history, and the importance of material strength of Kuiper belt objects1,2,3,4. Small, sub-kilometre-sized, Kuiper belt objects elude direct detection, but the signature of their occultations of background stars should be detectable5,6,7,8,9. Observations at both optical10 and X-ray11 wavelengths claim to have detected such occultations, but their implied abundances are inconsistent with each other and far exceed theoretical expectations. Here we report an analysis of Archival Data that reveals an occultation by a body with an approximately 500-metre radius at a distance of 45 astronomical units. The probability of this event arising from random statistical fluctuations within our Data set is about two per cent. Our survey yields a surface density of Kuiper belt objects with radii exceeding 250 metres of , ruling out inferred surface densities from previous claimed detections by more than 5σ. The detection of only one event reveals a deficit of sub-kilometre-sized Kuiper belt objects compared to a population extrapolated from objects with radii exceeding 50 kilometres. This implies that sub-kilometre-sized objects are undergoing collisional erosion, just like debris disks observed around other stars.
