Publications by authors named "W Brandner"
Article Synopsis
- Brown dwarf companions to stars help us understand planet formation processes, but some of them are more massive than expected based on their luminosities and host star ages.
- Gliese 229 B, previously thought to be a single entity, was revealed through observations to actually be two brown dwarfs, Gliese 229 Ba and Bb, with masses of 38.1 and 34.4 Jupiter masses, respectively.
- This discovery challenges existing theories and raises questions about the formation and occurrence of binary brown dwarfs in close orbits around stars.
Tight relationships exist in the local Universe between the central stellar properties of galaxies and the mass of their supermassive black hole (SMBH). These suggest that galaxies and black holes co-evolve, with the main regulation mechanism being energetic feedback from accretion onto the black hole during its quasar phase. A crucial question is how the relationship between black holes and galaxies evolves with time; a key epoch to examine this relationship is at the peaks of star formation and black hole growth 8-12 billion years ago (redshifts 1-3).
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- The star S2, orbiting the black hole Sagittarius A*, undergoes notable changes in gravitational potential, which researchers use to test the local position invariance (LPI) part of the Einstein equivalence principle.
- By analyzing the redshift of hydrogen and helium absorption lines in the star's spectrum during its closest approach to the black hole, the study aims to establish an upper limit on LPI violations.
- The research findings suggest that the tested gravitational potential variation is six times greater than what can be measured on Earth and ten times larger than previous experiments with white dwarfs, marking a new testing regime for the LPI.
A radial velocity (RV) survey for intermediate-mass giants has been operated for over a decade at Okayama Astrophysical Observatory (OAO). The OAO survey has revealed that some giants show long-term linear RV accelerations (RV trends), indicating the presence of outer companions. Direct imaging observations can help clarify what objects generate these RV trends.
View Article and Find Full Text PDFNear-infrared imaging polarimetry of LkCa 15: A possible warped inner disk.
Publ Astron Soc Jpn Nihon Tenmon Gakkai
April 2016
We present high-contrast -band polarized intensity images of the transitional disk around the young solar-like star LkCa 15. By utilizing Subaru/HiCIAO for polarimetric differential imaging, the angular resolution and the inner working angle reach 007 and = 0″.1, respectively.
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