Astronomy

Don Quixote was discovered in 1983 and although it has a perfectly comet-like orbit, no cometary activity (a tail or a coma around the object) have been observed. According to protocol, the object was listed as an asteroid. In 2009, we found from observations with the now defunct Spitzer Space Telescope that there actually is a faint coma around Don Quixote that most likely consists of molecular band emission from either CO or CO2. This is discussed in detail here and in this paper. ...

Motivation Most (optical) telescopes have to be protected from precipitation to prevent damage to their optics and electronics. For this reason, most observatories use all-sky cameras - cheap, but very sensitive CMOS cameras equipped with fish-eye lenses - that monitor the night sky for incoming clouds. Telescope operators can observe live streams from these cameras to make informed decisions as to whether the current weather situation requires the closing of the telescope dome, or not. ...

Ever since the early days of my PhD thesis, I have been involved in the thermal modeling of thermal-infrared observations of near-Earth objects and other asteroids. Such asteroid thermal models simulate the surface temperature distributions of asteroids utilizing some simplifying assumptions and enabling the estimation of physical properties like size and albedo. In the framework of several large-scale Spitzer Space Telescope observing programs, we have observed more than 2000 near-Earth objects and measured their thermal emission to constrain their diameters and albedos. Now that Spitzer has officially retired, we have finalized our observations and analysis, and compiled all of our results in one large data set. This compilation comprises 2204 diameter and geometric albedo estimates for 2132 different near-Earth objects - the largest homogeneous data set of its kind for this population. The results of these efforts are available GitHub. ...

TESS is the Transiting Exoplanet Survey Satellite, which was launched into space by NASA in 2018 to identify faint brightness variations in stars that are characteristic of planets orbiting around and transiting in front of these stars. A rendering of the TESS spacecraft. The instrument consists of four imaging cameras, each covering 24° x 24° of the sky. Over the course of its nominal two-year mission, TESS will monitor more than 200,000 stars with the photometric accuracy necessary to identify exoplanet transits. In order to observe this huge number of stars, TESS points at different “Sectors” in the sky, amounting to a total of 85% of the entire sky. Each Sector spanning 24° x 96° is observed over a period of about one month. ...

The ESA mission Gaia not only observes a good fraction of the stars in the milky way, but also a huge number of asteroids. Gaia Data Release 2 (DR2) is the first data release to include a number of asteroid observations, limited to G magnitudes (no color information) and a pre-selected sample of 14099 asteroids from different populations. For each asteroids, DR2 contains a median number of 9 observations over the first 9 months of the mission. While this limited data set does not allow for deriving the targets’ rotational periods or constraining their taxonomic types, it is useful for a look into the shape distribution of asteroids. ...

The vast majority of all asteroid diameters and albedos that are currently available have been derived from thermal infrared observations using a method called thermal modeling. Thermal models simulate the surface temperature distribution on an asteroid which is used to derive the thermal infrared flux that is emitted by the body. By varying the model parameters - mainly its diameter and albedo - the properties of an asteroid can be fit to observations of the thermal emission and hence estimated. ...

sbpy is an astropy affiliated package that will provide tools for small-body planetary astronomers. The idea is provide a collection of well-tested and documented tools that asteroid and comet observers use on a daily basis. The goal is to improve the reproducibility of results and to make it easier for (young) researchers to try out new ideas. The development of sbpy has just started, as our NASA PDART grant just recently arrived. A lot of work to be done, but a few glimpses of its usefulness can already be seen. ...

In the framework of the MANOS program, I have been working on an automated data analysis pipeline for calibrated asteroid photometry and astrometry from imaging data. This pipeline, which can be applied to any kind of point source observations, is now in a robust state and available through github. For details on the pipeline, please refer to official publication (see below). Resources Mommert, M. (2017), “PHOTOMETRYPIPELINE: An automated pipeline for calibrated photometry”, Astronomy and Computing, 18, 47., publication, arxiv

One long-standing question is: how many asteroids - especially near-Earth asteroids (NEAs) - were comets in the past? In the classical conception, comets have surface ices and form tails and comae in the vicinity of the Sun; asteroids are simply rocks in space. In the recent years, the two classifications became less clear than that. Comets can end up on orbits that bring them close to the Earth. We can observe them. But what happens to them after spending a while there? For some comets, like ISON, being close to the Sun is fatal; they simply disintegrate and disappear. For other comets in near-Earth space, the strong degree of insolation forces them to lose their surface ices quickly and eventually their activity stops - they are dead or dormant comets. Since comet surfaces have very low albedos, these dead comets simply look like low-albedo asteroids and are really hard to identify. ...

The understanding of the compositional distribution of NEOs is important to reconstruct their dynamical and physical evolution, assess the damage potential in case of an impact, and estimate the resources that can be obtained from these bodies in the not-so-far future. Also, there is still a discrepancy between the compositional distribution of meteoritic material found on Earth and the overall composition of the NEO distribution. The most common way to investigate the compositions of asteroids is to perform spectroscopic observations: wavelength-dependent variations of the surface reflectance can be diagnostic for the composition of an object and allow for a taxonomic classification. However, spectroscopic observations are usually only possible for bright and large asteroids and require large telescopes for small asteroids. ...