During the last decades, growing evidence about the presence of planetary material around white dwarfs has been established. The features of heavy elements in the spectra of a large fraction (25-50%) of these objects needs a frequent accretion of material orbiting close to the white dwarf. Additionally, at least 4% of these objects are known to host dusty disks. The space mission K2, that re-uses the Kepler instrument after a failure of two of its four gyroscopes, recently detected transiting material around WD1145+017, with periods in the 4.5-5h range, and a depth variability with scales of a few days. This is attributed to the presence of disintegrating planetesimals, due to the high temperatures close to the white dwarf. The K2 data suffer from a poor sampling to study this object (30 min), and they lack chromatic information. In this work, we used the IAC80 telescope to predict deep transits that were observed a few hours later with OSIRIS at GTC. The close to 1-min sampling, and the information in four visible bands, allowed for the first detection, with an unprecedented precision, of the color of the transiting material. The lack of depth changes in the different bands (gray transits) served to set constraints to the minimal particle sizes of the transiting material, which have to be 0.5 microns or larger for the most common minerals.
Advertised on
References
It may interest you
-
The universality of the stellar initial mass function (IMF) is one of the most widespread assumptions in modern Astronomy and yet, it might be flawed. While observations in the Milky Way generally support an IMF that is invariant with respect to the local conditions under which stars form, measurements of massive early-type galaxies systematically point towards a non-universal IMF. To bridge the gap between both sets of evidence, in this work we measured for the first time the low-mass end of the IMF from the integrated spectra of a Milky Way-like galaxy, NGC3351. We found that the slope ofAdvertised on
-
Massive stars, those over ten times heavier than our Sun, are the conduits of most elements of the periodic table and drive the morphological and chemical makeup of their host galaxies. Yet the origin of the most luminous and hottest stars among them, called 'blue supergiants', has been debated for many decades. Blue supergiants are strange stars. First, they are observed in large numbers, despite conventional stellar physics expecting them to live only briefly. Second, they are typically found alone, despite most massive stars being born with companions. Third, the majority of them harbourAdvertised on
-
The formation and evolution of the disk of our Galaxy, the Milky Way, remains an enigma in astronomy. In particular, the relationship between the thick disk and the thin disk —two key components of the Milky Way— is still unclear. Understanding the chemical and dynamical properties of the stars within these disks is crucial, especially in the parameter spaces where their characteristics overlap, such the metallicity regime around [Fe/H] ~ -0.7, which marks the metal-poor end of the thin disk, higher than that of the thick disk. This is often interpreted as an indication that the thin diskAdvertised on