125 research outputs found
A History and Informal Assessment of the Slacker Astronomy Podcast
Slacker Astronomy is a weekly podcast that covers a recent astronomical news
event or discovery. The show has a unique style consisting of irreverent,
over-the-top humor combined with a healthy dose of hard science. According to
our demographic analysis, the combination of this style and the unique
podcasting distribution mechanism allows the show to reach audiences younger
and busier than those reached via traditional channels. We report on the
successes and challenges of the first year of the show, and provide an informal
assessment of its role as a source for astronomical news and concepts for its
approximately 15,500 weekly listeners.Comment: 14 page
A Decade Of Starspot Activity On The Eclipsing Short-Period RS Canum Venaticorum Star WY Cancri: 1988-1997
We present optical photometry of the short-period eclipsing RS CVn system WY Cancri for the years 1988â1997. For each light curve, we model the distortion waves in order to study the behavior of starspots in this system. After removing the spot effects f
Towards Closing the Window on Strongly Interacting Dark Matter: Far-Reaching Constraints from Earth's Heat Flow
We point out a new and largely model-independent constraint on the dark
matter scattering cross section with nucleons, applying when this quantity is
larger than for typical weakly interacting dark matter candidates. When the
dark matter capture rate in Earth is efficient, the rate of energy deposition
by dark matter self-annihilation products would grossly exceed the measured
heat flow of Earth. This improves the spin-independent cross section
constraints by many orders of magnitude, and closes the window between
astrophysical constraints (at very large cross sections) and underground
detector constraints (at small cross sections). In the applicable mass range,
from about 1 to about 10^{10} GeV, the scattering cross section of dark matter
with nucleons is then bounded from above by the latter constraints, and hence
must be truly weak, as usually assumed.Comment: 12 pages, 2 figures; minor updates to match published versio
EVN observations of 6.7 GHz methanol maser polarization in massive star-forming regions
The role of magnetic fields in the formation of high-mass stars is still
under debate, and recent measurements of their orientation and strength by
using polarized maser emissions are contributing new insights. Masers
polarization, in particular of the 6.7-GHz methanol masers, are one of the best
probes of the magnetic field morphologies around massive protostars.
Determining the magnetic field morphology around an increasing number of
massive protostars at milliarcsecond resolution by observing 6.7-GHz methanol
masers is crucial to better understand the role of magnetic fields in massive
star formation.The First EVN Group consists of 4 massive star-forming
complexes: W51, W48, IRAS18556+0138, and W3(OH). These contain well-studied
\hii ~regions from some of which molecular bipolar outflows were also detected
(W51-e2, G35.20-0.74N). Nine of the European VLBI Network antennas were used to
measure the linear polarization and Zeeman-splitting of the 6.7-GHz methanol
masers in the star-forming regions of the First EVN Group. We detected a total
of 154 CH3OH masers, one third of these towards W3(OH). Fractional linear
polarization (1.2-11.5%) was detected towards 55 masers. The linear
polarization vectors are well-ordered in all the massive star-forming regions.
We measured significant Zeeman-splitting in 3 massive star-forming regions
(W51, W48, and W3(OH)) revealing a range of separations -3.5 m/s<\Delta
V_{z}<3.8 m/s with the smallest |\Delta V_{z}|=0.4m/s. We were also able to
compare our magnetic field results with those obtained from submillimeter
wavelength dust observation in W51 and show that the magnetic field at low and
high resolutions are in perfect agreement.Comment: 15 pages, 11 figures, 5 tables, accepted by Astronomy & Astrophysic
Locating the festival, positioning the feast: natural and calendar festivals in medieval Slovenia
The astronomical cycles and occurrences of the Sun, Moon, planets and certain
star constellations were well known to prehistoric, Roman and medieval communities.
Archaeoastronomy studies how ancient societies incorporated this
knowledge into various aspects of past cultures. The discipline draws on modern
astronomy, geodesy, physics, statistics, anthropology, ethnology and archaeology
to study and interpret a wide range of source materials, from structural
alignments to art, artefacts and inscriptions. This paper presents archaeoastronomical
research on the orientation of Romanesque churches across the territory
of modern-day Slovenia, focusing on an array of medieval festivals associated
with the solstices and equinoxes. It demonstrates a profound connection
between these festivals and the alignment of churches
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