The Origin of (90) Antiope From Component-Resolved Near-Infrared Spectroscopy

The origin of the similary-sized binary asteroid (90) Antiope remains an unsolved puzzle. To constrain the origin of this unique double system, we recorded individual spectra of the components using SPIFFI, a near-infrared integral field spectrograph fed by SINFONI, an adaptive optics module available on VLT-UT4. Using our previously published orbital model, we requested telescope time when the separation of the components of (90) Antiope was larger than 0.087", to minimize the contamination between components, during the February 2009 opposition. Several multi-spectral data-cubes in J band (SNR=40) and H+K band (SNR=100) were recorded in three epochs and revealed the two components of (90) Antiope. After developing a specific photometric extraction method and running an error analysis by Monte-Carlo simulations, we successfully extracted reliable spectra of both components from 1.1 to 2.4 um taken on the night of February 21, 2009. These spectra do not display any significant absorption features due to mafic mineral, ices, or organics, and their slopes are in agreement with both components being C- or Cb- type asteroids. Their constant flux ratio indicates that both components' surface reflectances are quite similar, with a 1-sigma variation of 7%. By comparison with 2MASS J, H, K color distribution of observed Themis family members, we conclude that both bodies were most likely formed at the same time and from the same material. The similarly-sized system could indeed be the result of the breakup of a rubble-pile proto-Antiope into two equal-sized bodies, but other scenarios of formation implying a common origin should also be considered.Comment: 46 pages, 1 table, 11 figures accepted for publication to Icaru

Thunderstorm electric fields probed by extensive air showers through their polarized radio emission

Contains fulltext : 173575.pdf (publisher's version ) (Open Access

Probing atmospheric electric fields in thunderstorms through radio emission from cosmic-ray-induced air showers

We present measurements of radio emission from cosmic ray air showers that took place during thunderstorms. The intensity and polarization patterns of these air showers are radically different from those measured during fair-weather conditions. With the use of a simple two-layer model for the atmospheric electric field, these patterns can be well reproduced by state-of-the-art simulation codes. This in turn provides a novel way to study atmospheric electric fields

On searches for coherent radio emission from the transient radio sky

Contains fulltext : 205924.pdf (publisher's version ) (Open Access)Radboud University, 29 augustus 2019Promotor : Falcke, H.D.E.V, 279 p

Composition, mineralogy, and porosity of multiple asteroid systems from visible and near-infrared spectral data

Contains fulltext : 139597.pdf (preprint version ) (Open Access

Choosing a Maximum Drift Rate in a SETI Search: Astrophysical Considerations

Contains fulltext : 209196.pdf (publisher's version ) (Open Access)A radio transmitter that is accelerating with a non-zero radial component with respect to a receiver will produce a signal that appears to change its frequency over time. This effect, commonly produced in astrophysical situations where orbital and rotational motions are ubiquitous, is called a drift rate. In radio SETI (Search for Extraterrestrial Intelligence) research, it is unknown a priori which frequency a signal is being sent at, or even if there will be any drift rate at all besides motions within the solar system. Therefore drift rates across the potential range need to be individually searched and a maximum drift rate needs to be chosen. The middle of this range is zero, indicating no acceleration, but the absolute value for the limits remains unconstrained. A balance must be struck between computational time and the possibility of excluding a signal from an ETI. In this work, we examine physical considerations that constrain a maximum drift rate and highlight the importance of this problem in any narrowband SETI search. We determine that a normalized drift rate of 200 nHz (e.g., 200 Hz s−1 at 1 GHz) is a generous, physically motivated guideline for the maximum drift rate that should be applied to future narrowband SETI projects if computational capabilities permit

Blimpy: Breakthrough Listen I/O Methods for Python

Contains fulltext : 209195.pdf (publisher's version ) (Open Access