Distribution and spectrophotometric classification of basaltic asteroids

ABSTRACT We aim to determine the distribution of basaltic asteroids (classified as V-types) based on the spectrophotometric data reported in the MOVIS-C catalogue. A total of 782 asteroids were identified. The observations with all four filters (Y, J, H, Ks), available for 297 of these candidates, allow a reliable comparison with the laboratory data of howardite, eucrite, and diogenite meteorites. We found that the majority of the basaltic candidates (≈95${{\ \rm per\ cent}}$) are located in the inner main belt, while only 29 (≈4${{\ \rm per\ cent}}$) and 8 (≈1${{\ \rm per\ cent}}$) are located in the middle (MMB) and outer main belt (OMB), respectively. A fraction of ≈33${{\ \rm per\ cent}}$ from the V-type candidates is associated with the Vesta family (with respect to AstDyS). We also identified four MMB V-type candidates belonging to (15) Eunomia family, and another four low inclination ones corresponding to (135) Hertha. We report differences between the colour indices and albedo distributions of the V-type candidates located in the inner main belt compared to those from the MMB and OMB. These results support the hypothesis of a different origin for the basaltic asteroids with a semimajor axis beyond 2.5 au. Furthermore, lithological differences are present between the vestoids and the inner low inclination basaltic asteroids. The data allow us to estimate the unbiased distribution of basaltic asteroids across the main asteroid belt. We highlight that at least 80${{\ \rm per\ cent}}$ of the ejected basaltic material from (4) Vesta is missing or is not yet detected because it is fragmented in sizes smaller than 1 km.

Download Full-text

The last pieces of the primitive inner belt puzzle: Klio, Chaldaea, Chimaera, and Svea

Astronomy and Astrophysics ◽

10.1051/0004-6361/201935992 ◽

2019 ◽

Vol 630 ◽

pp. A141 ◽

Cited By ~ 5

Author(s):

David Morate ◽

Julia de León ◽

Mário De Prá ◽

Javier Licandro ◽

Noemí Pinilla-Alonso ◽

...

Keyword(s):

Asteroid Belt ◽

Main Belt ◽

Absorption Bands ◽

Aqueous Alteration ◽

Visible Spectra ◽

Main Asteroid Belt ◽

Taxonomical Classification ◽

Inner Region ◽

Near Earth Asteroids

Aims. Several primitive families in the inner region of the main asteroid belt were identified as potential sources for two near-Earth asteroids (NEAs), (101955) Bennu and (162173) Ryugu, targets of the sample-return missions OSIRIS-REx and Hayabusa2, respectively. Four of the families, located at high proper inclinations (i > 10°), have not yet been compositionally studied: Klio, Chaldaea, Chimaera, and Svea. We want to characterize and analyze these families within the context of our PRIMitive Asteroid Spectroscopic Survey (PRIMASS), in order to complete the puzzle of the origins of the two NEAs. Methods. We obtained visible spectra (0.5–0.9 μm) of a total of 73 asteroids within the Klio, Chaldaea, Chimaera, and Svea collisional families, using the instrument OSIRIS at the 10.4 m Gran Telescopio Canarias. We performed a taxonomical classification of these objects, and an analysis of the possible presence of absorption bands related to aqueous alterations, comparing the results with already studied primitive families in the inner main belt. Results. We present here reflectance spectra for 30 asteroids in the Klio family, 15 in Chaldaea, 20 in Chimaera, and 8 in Svea. We show that Klio, Chaldaea, and Chimaera members have moderately red spectral slopes, with aqueous alteration absorption bands centered around 0.7 μm, characteristic of the group of primitive families known as Erigone-like. In contrast, Svea shows no 0.7 μm features, and neutral and blue spectral slopes, and thus is a Polana-like family. While all four families might be related to (162173) Ryugu, the only family studied in this work that might be related to (101955) Bennu is Svea.

Download Full-text

New multi-part collisional model of the main belt: the contribution to near-Earth asteroids

Astronomy and Astrophysics ◽

10.1051/0004-6361/202037458 ◽

2020 ◽

Vol 639 ◽

pp. A9

Author(s):

P. S. Zain ◽

G. C. de Elía ◽

R. P. Di Sisto

Keyword(s):

Significant Contribution ◽

Asteroid Belt ◽

Size Distributions ◽

Main Belt ◽

Yarkovsky Effect ◽

Source Regions ◽

Main Asteroid Belt ◽

Near Earth Asteroids ◽

Asteroid Families ◽

Collisional Evolution

Aims. We developed a six-part collisional evolution model of the main asteroid belt (MB) and used it to study the contribution of the different regions of the MB to the near-Earth asteroids (NEAs). Methods. We built a statistical code called ACDC that simulates the collisional evolution of the MB split into six regions (namely Inner, Middle, Pristine, Outer, Cybele and High-Inclination belts) according to the positions of the major resonances present there (ν6, 3:1J, 5:2J, 7:3J and 2:1J). We consider the Yarkovsky effect and the mentioned resonances as the main mechanism that removes asteroids from the different regions of the MB and delivers them to the NEA region. We calculated the evolution of the NEAs coming from the different source regions by considering the bodies delivered by the resonances and mean dynamical timescales in the NEA population. Results. Our model is in agreement with the major observational constraints associated with the MB, such as the size distributions of the different regions of the MB and the number of large asteroid families. It is also able to reproduce the observed NEAs with H < 16 and agrees with recent estimations for H < 20, but deviates for smaller sizes. We find that most sources make a significant contribution to the NEAs; however the Inner and Middle belts stand out as the most important source of NEAs followed by the Outer belt. The contributions of the Pristine and Cybele regions are minor. The High-Inclination belt is the source of only a fraction of the actual observed NEAs with high inclination, as there are dynamical processes in that region that enable asteroids to increase and decrease their inclinations.

Download Full-text

Recurrent Activity from Active Asteroid (248370) 2005 QN173: A Main-belt Comet

The Astrophysical Journal ◽

10.3847/2041-8213/ac365b ◽

2021 ◽

Vol 922 (1) ◽

pp. L8 ◽

Cited By ~ 1

Author(s):

Colin Orion Chandler ◽

Chadwick A. Trujillo ◽

Henry H. Hsieh

Keyword(s):

Solar System ◽

Detection Technique ◽

Asteroid Belt ◽

The Sun ◽

Activity Detection ◽

Main Belt ◽

Solar System Objects ◽

Recurrent Activity ◽

Main Asteroid Belt

Abstract We present archival observations of main-belt asteroid (248370) 2005 QN173 (also designated 433P) that demonstrate this recently discovered active asteroid (a body with a dynamically asteroidal orbit displaying a tail or coma) has had at least one additional apparition of activity near perihelion during a prior orbit. We discovered evidence of this second activity epoch in an image captured 2016 July 22 with the DECam on the 4 m Blanco telescope at the Cerro Tololo Inter-American Observatory in Chile. As of this writing, (248370) 2005 QN173 is just the eighth active asteroid demonstrated to undergo recurrent activity near perihelion. Our analyses demonstrate (248370) 2005 QN173 is likely a member of the active asteroid subset known as main-belt comets, a group of objects that orbit in the main asteroid belt that exhibit activity that is specifically driven by sublimation. We implement an activity detection technique, wedge photometry, that has the potential to detect tails in images of solar system objects and quantify their agreement with computed antisolar and antimotion vectors normally associated with observed tail directions. We present a catalog and an image gallery of archival observations. The object will soon become unobservable as it passes behind the Sun as seen from Earth, and when it again becomes visible (late 2022) it will be farther than 3 au from the Sun. Our findings suggest (248370) 2005 QN173 is most active interior to 2.7 au (0.3 au from perihelion), so we encourage the community to observe and study this special object before 2021 December.

Download Full-text

Basaltic material across the Main Asteroid Belt

10.5194/epsc2020-368 ◽

2020 ◽

Author(s):

Jad Alexandru Mansour ◽

Marcel Popescu ◽

Javier Licandro ◽

Julia de Leon

Keyword(s):

Asteroid Belt ◽

Main Asteroid Belt ◽

Basaltic Material

Download Full-text

Dynamical evolution of near-Earth objects

10.5194/epsc2020-1104 ◽

2020 ◽

Author(s):

Athanasia Toliou ◽

Mikael Granvik

Keyword(s):

Semimajor Axis ◽

Dynamical Evolution ◽

Orbital Evolution ◽

Derived Categories ◽

Asteroid Belt ◽

The Sun ◽

Escape Route ◽

Perihelion Distance ◽

Main Asteroid Belt ◽

Near Earth Objects

An apparent discrepancy between the number of observed near-Earth objects (NEOs) with small perihelion distances (q) and the number of objects that models predict, has led to the conclusion that asteroids get destroyed at non-trivial distances from the Sun. Consequently, there must be a, possibly thermal, mechanism at play, responsible for breaking up asteroids asteroids in such orbits. We studied the dynamical evolution of ficticious NEOs whose perihelion distance reaches below the average disruption distance q_dis=0.076 au, as suggested by Granvik et al. (2016). To that end, we used the orbital integrations of objects that escaped from the main asteroid belt (Granvik et al. 2017), and entered the near-Earth region (Granvik et al. 2018). First, we investigated a variety of mechanisms that can lower the perihelion distance of an object to a small-enough value. In particular, we considered mean-motion resonances with Jupiter, secular resonances with Jupiter and Saturn (v_5 and v_6) and also the Kozai resonance. We developed a code that calculates the evolution of the critical argument of all the relevant resonances and identifies librations during the last stages of an object's orbital evolution, namely, just before q=q_dis. Any subsequent evolution of the object was disregarded, since we considered it disrupted. The accuracy of our model is ~96%. In addition, we measured the dynamical 'lifetimes' of NEOs when they orbit the innermost parts of the inner Solar System. More precisely, we calculated the total time it takes for the q of each object to go from 0.4 au to q_dis (&#964;_lq). The outer limit of this range was chosen such because it is a) the approximate semimajor axis of Mercury, and b) an absence of sub-meter-sized boulders with q smaller than this distance has been proposed by Wiegert et al (2020). Combining this measure with the recorded resonances, we can get a sense of the timescale of each q-lowering mechanism. Next, for a more rigorous study of the evolution of the NEOs with q<0.4 au, we divided this region in bins and measured the relevant time they spend at different distances from the Sun. Together with the total time spent in each bin, we kept track of the number of times that q entered one of the bins. Finally, we computed the actual time each object spends in each bin during its evolution, i.e., the total time it spends in a specific range in radial heliocentric distance. By following this approach, we derived categories of typical evolutions of NEOs that reach the average disruption distance. In addition, since we have the information concerning the escape route from the main asteroid belt followed by each NEO, we linked the q-lowering mechanism and the associated orbital evolutions in the range below the orbit of Mercury, to their source regions and thus were able to draw conclusions abour their physical properties.

Download Full-text

Main-belt comets: sublimation-driven activity in the asteroid belt

Proceedings of the International Astronomical Union ◽

10.1017/s1743921315008546 ◽

2015 ◽

Vol 10 (S318) ◽

pp. 99-110

Author(s):

Henry H. Hsieh

Keyword(s):

Thermal Properties ◽

Solar System ◽

Asteroid Belt ◽

Main Belt ◽

New Class ◽

Solar System Objects ◽

Main Asteroid Belt

AbstractOur knowledge of main-belt comets (MBCs), which exhibit comet-like activity likely due to the sublimation of volatile ices, yet orbit in the main asteroid belt, has increased greatly since the discovery of the first known MBC, 133P/Elst-Pizarro, in 1996, and their recognition as a new class of solar system objects after the discovery of two more MBCs in 2005. I review work that has been done over the last 10 years to improve our understanding of these enigmatic objects, including the development of systematic discovery methods and diagnostics for distinguishing MBCs from disrupted asteroids (which exhibit comet-like activity due to physical disruptions such as impacts or rotational destabilization). I also discuss efforts to understand the dynamical and thermal properties of these objects.

Download Full-text

Active Asteroids: Main-Belt Comets and Disrupted Asteroids

Proceedings of the International Astronomical Union ◽

10.1017/s1743921316002969 ◽

2015 ◽

Vol 11 (A29A) ◽

pp. 237-240

Author(s):

Henry H. Hsieh

Keyword(s):

Asteroid Belt ◽

Main Belt ◽

New Class ◽

Main Asteroid Belt ◽

Areas Of Interest

AbstractThe study of active asteroids has attracted a great deal of interest in recent years since the recognition of main-belt comets (which orbit in the main asteroid belt, but exhibit comet-like activity due to the sublimation of volatile ices) as a new class of comets in 2006, and the discovery of the first disrupted asteroids (which, unlike MBCs, exhibit comet-like activity due to a physical disruption such as an impact or rotational destabilization, not sublimation) in 2010. In this paper, I will briefly discuss key areas of interest in the study of active asteroids.

Download Full-text

Main-Belt Comets as Tracers of Ice in the Inner Solar System

Proceedings of the International Astronomical Union ◽

10.1017/s1743921313012866 ◽

2012 ◽

Vol 8 (S293) ◽

pp. 212-218 ◽

Cited By ~ 1

Author(s):

Henry H. Hsieh

Keyword(s):

Solar System ◽

Asteroid Belt ◽

Main Belt ◽

Small Bodies ◽

Water Ice ◽

History Of ◽

Compositional History ◽

Main Asteroid Belt ◽

Abundance And Distribution ◽

Ice Sublimation

AbstractAs a recently recognized class of objects exhibiting apparently cometary (sublimation-driven) activity yet orbiting completely within the main asteroid belt, main-belt comets (MBCs) have revealed the existence of present-day ice in small bodies in the inner solar system and offer an opportunity to better understand the thermal and compositional history of our solar system, and by extension, those of other planetary systems as well. Achieving these overall goals, however, will require meeting various intermediate research objectives, including discovering many more MBCs than the currently known seven objects in order to ascertain the population's true abundance and distribution, confirming that water ice sublimation is in fact the driver of activity in these objects, and improving our understanding of the physical, dynamical, and thermal evolutionary processes that have acted on this population over the age of the solar system.

Download Full-text

On a possibility of transfer of asteroids from the 2:1 mean motion resonance with Jupiter to the Centaur zone

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stab1078 ◽

2021 ◽

Author(s):

Kazantsev Anatolii ◽

Kazantseva Lilia

Keyword(s):

Terrestrial Planet ◽

Numerical Calculations ◽

Asteroid Belt ◽

Time Interval ◽

Transfer Time ◽

Mean Motion ◽

Resonant Orbits ◽

Main Asteroid Belt ◽

Absolute Magnitudes ◽

Mean Motion Resonance

ABSTRACT The paper analyses possible transfers of bodies from the main asteroid belt (MBA) to the Centaur region. The orbits of asteroids in the 2:1 mean motion resonance (MMR) with Jupiter are analysed. We selected the asteroids that are in resonant orbits with e > 0.3 whose absolute magnitudes H do not exceed 16 m. The total number of the orbits amounts to 152. Numerical calculations were performed to evaluate the evolution of the orbits over 100,000-year time interval with projects for the future. Six bodies are found to have moved from the 2:1 commensurability zone to the Centaur population. The transfer time of these bodies to the Centaur zone ranges from 4,600 to 70,000 yr. Such transfers occur after orbits leave the resonance and the bodies approach Jupiter Where after reaching sufficient orbital eccentricities bodies approach a terrestrial planet, their orbits go out of the MMR. Accuracy estimations are carried out to confirm the possible asteroid transfers to the Centaur region.

Download Full-text

The Spectrum of Bacille Calmette–Guérin Diseases in Children—A Decade of Data from Neonatal Vaccination Settings

Vaccines ◽

10.3390/vaccines9020150 ◽

2021 ◽

Vol 9 (2) ◽

pp. 150

Author(s):

Noora Al Busaidi ◽

Prakash KP ◽

Amina Al-Jardani ◽

Nashat Al-Sukaiti ◽

Salem Al Tamemi ◽

...

Keyword(s):

Laboratory Data ◽

International Classification Of Diseases ◽

Bcg Vaccine ◽

Bacille Calmette Guerin ◽

Related Disease ◽

Central Public Health ◽

Classification Of Diseases ◽

Polymerase Chain ◽

Disseminated Disease

In this paper, we present a multicentre record-based descriptive study used to estimate the incidence and characterize the spectrum of confirmed bacille Calmette–Guérin (BCG) vaccine-related disease among children in Oman. This study included all children (age ≤ 14 years) who had culture and/or polymerase chain reaction (PCR)-confirmed BCG disease from January 2006 to December 2018, as identified from Central Public Health Laboratory data and International Classification of Diseases coding of an electronic patient information system. In total, 88 children confirmed to have BCG disease were included in the study, making an average incidence of 9.2 cases per 100,000 vaccinated neonates. The males comprised 65.9%, Omanis 93.2%, and the median age of presentation was 4 months in children with BCG disease. The most common type of disease was BCG abscesses (72.4%). Children with immunodeficiency and those presenting within 6 months were found to have a more severe and disseminated disease. In total, 28 children had immunodeficiency. The age of presentation and type of BCG disease was significantly associated with immunodeficiency status. The majority of cases required therapy (both medical and surgical) and recovered well. The incidence of laboratory-confirmed BCG vaccine-related disease was low in Oman supporting continuing the use of the BCG vaccination practice at birth.

Download Full-text