In 2015 we coordinated an international observational campaign dedicated to the characterization of (357439) 2004 BL86 on its close approach to Earth.
The potentially hazardous asteroid (PHA) (357439) 2004 BL86 grazed Earth on January 26, 2015 at a distance of about 1.2 million km. This favorable geometry allowed observing it to derive its physical and dynamical parameters. (357439) 2004 BL86 was previously estimated to be a 500-m body. We study it also considering possible mechanisms that might mitigate the effect of asteroids that might become dangerous for Earth. Physical and dynamical investigations of this peculiar object were performed for its characterization. We used spectral observations obtained in the visible (V) using the Isaac Newton Telescope and in the near-infrared (NIR) using the InfraRed Telescope Facility. A complementary photometric survey during two nights was also provided by the Astronomical Observatory Cluj-Feleacu station in Romania. We anlyzed the data using reliable mathematical tools that were previously published under the acronym M4AST.
The mineralogical analysis reveals its similarities to howardite-eucrite-diogenite meteorites. The band analysis reveals that the object is more similar to a eucritic and howarditic composition, and that it originated from the crust of a large parent body.
Characterization of (357439) 2004 BL86 on its close approach to Earth in 2015, M. Birlan, M. Popescu, D.A. Nedelcu, V. Turcu, A. Pop, B. Dumitru, F. Stevance, O. Vaduvescu, D. Moldovan, P. Rocher, A. Sonka, and L. Mircea, DOI: http://dx.doi.org/10.1051/0004-6361/201526460
In a new paper, recently published in the journal Astronomy and Astrophysics, we report near-infrared spectroscopic observations of one of the largest potentially hazardous asteroids, (214869) 2007 PA8. Mineralogical analysis of this object was followed by the investigation of the dynamical delivery mechanism from its probable source region, based on long-term numerical integrations.
The spectrum of (214869) 2007 PA8 was analyzed using the positions of 1 μm and 2 μm bands and by curve-matching with RELAB meteorites spectra. Its dynamical evolution was investigated by means of a 200 000-year numerical integration in the past of 1275 clones followed to the source region. (214869) 2007 PA8 has a very young surface with a composition more akin to H chondrites than to any other type of ordinary chondrite. It arrived from the outer Main Belt in the near-Earth space via the 5:2 mean motion resonance with Jupiter by eccentricity pumping.
Identification of its source region far from (6) Hebe raises the possibility of the existence of a second parent body of the H chondrites that has a radically different post-accretion history. Future spectroscopic surveys in the 5:2 resonance region will most likely discover other asteroids with an H chondrite composition.
Evidence for a source of H chondrites in the outer main asteroid belt, D.A. Nedelcu, M. Birlan, M. Popescu, O. Badescu, D. Pricopi, DOI: http://dx.doi.org/10.1051/0004-6361/201423949
In a second paper published in 2014 in the journal Astronomy and Astrophysics we investigate Taurid Complex, a massive stream of material in the inner part of the Solar System considered by some authors to have a common cometary origin. The asteroids belonging to Taurid Complex are on Apollo type orbit, with most of them being flagged as potentially hazardous asteroids. In this context, understanding the nature and the origin of this asteroidal population is not only of scientific interest but also of practical importance.
We obtained spectra of six of the largest asteroids (2201, 4183, 4486, 5143, 6063, and 269690) associated with Taurid complex. The observations were made with the IRTF telescope equipped with the spectro-imager SpeX. Their taxonomic classification is made using Bus-DeMeo taxonomy. The asteroid spectra are compared with the meteorite spectra from the Relab database.
Mineralogical models were applied to determine their surface composition. All the spectral analysis is made in the context of the already published physical data. Five of the objects studied in this paper present spectral characteristics similar to the S taxonomic complex. The spectra of ordinary chondrites (spanning H, L, and LL subtypes) are the best matches for these asteroid spectra. The asteroid (269690) 1996 RG3 presents a flat featureless spectrum which could be associated to a primitive C-type object. The increased reflectance above 2.1 microns constrains its geometrical albedo to a value around 0.03.
While there is an important dynamical grouping among the Taurid Complex asteroids, the spectral data of the largest objects do not support a common cometary origin. Furthermore, there are significant variations between the spectra acquired until now.
Spectral properties of the largest asteroids associated with Taurid Complex, M. Popescu, M. Birlan, D. A. Nedelcu, J. Vaubaillon, and C. P. Cristescu, DOI: http://dx.doi.org/10.1051/0004-6361/201424064