56 research outputs found
Coronavirus and the stock market: science cannot predict the outcome, but does it matter?
During the pandemic, not worrying too much about the stock market might be the best investors can do, write Nicolas Martelin and Jamie Nes
X-Ray Flashes in Recurrent Novae: M31N 2008-12a and the Implications of the Swift Non-detection
Models of nova outbursts suggest that an X-ray flash should occur just after
hydrogen ignition. However, this X-ray flash has never been observationally
confirmed. We present four theoretical light curves of the X-ray flash for two
very massive white dwarfs (WDs) of 1.380 and 1.385 M_sun and for two recurrence
periods of 0.5 and 1 years. The duration of the X-ray flash is shorter for a
more massive WD and for a longer recurrence period. The shortest duration of 14
hours (0.6 days) among the four cases is obtained for the 1.385 M_sun WD with
one year recurrence period. In general, a nova explosion is relatively weak for
a very short recurrence period, which results in a rather slow evolution toward
the optical peak. This slow timescale and the predictability of very short
recurrence period novae give us a chance to observe X-ray flashes of recurrent
novae. In this context, we report the first attempt, using the Swift
observatory, to detect an X-ray flash of the recurrent nova M31N 2008-12a (0.5
or 1 year recurrence period), which resulted in the non-detection of X-ray
emission during the period of 8 days before the optical detection. We discuss
the impact of these observations on nova outburst theory. The X-ray flash is
one of the last frontiers of nova studies and its detection is essentially
important to understand the pre-optical-maximum phase. We encourage further
observations.Comment: 12 pages, including 9 figures and 3 tables. To appear in the
Astrophysical Journa
Pedagogical Agents for Fostering Question-Asking Skills in Children
Question asking is an important tool for constructing academic knowledge, and
a self-reinforcing driver of curiosity. However, research has found that
question asking is infrequent in the classroom and children's questions are
often superficial, lacking deep reasoning. In this work, we developed a
pedagogical agent that encourages children to ask divergent-thinking questions,
a more complex form of questions that is associated with curiosity. We
conducted a study with 95 fifth grade students, who interacted with an agent
that encourages either convergent-thinking or divergent-thinking questions.
Results showed that both interventions increased the number of
divergent-thinking questions and the fluency of question asking, while they did
not significantly alter children's perception of curiosity despite their high
intrinsic motivation scores. In addition, children's curiosity trait has a
mediating effect on question asking under the divergent-thinking agent,
suggesting that question-asking interventions must be personalized to each
student based on their tendency to be curious.Comment: Accepted at CHI 202
Asteroseismology with the Roman Galactic Bulge Time-Domain Survey
Asteroseismology has transformed stellar astrophysics. Red giant
asteroseismology is a prime example, with oscillation periods and amplitudes
that are readily detectable with time-domain space-based telescopes. These
oscillations can be used to infer masses, ages and radii for large numbers of
stars, providing unique constraints on stellar populations in our galaxy. The
cadence, duration, and spatial resolution of the Roman galactic bulge
time-domain survey (GBTDS) are well-suited for asteroseismology and will probe
an important population not studied by prior missions. We identify photometric
precision as a key requirement for realizing the potential of asteroseismology
with Roman. A precision of 1 mmag per 15-min cadence or better for saturated
stars will enable detections of the populous red clump star population in the
Galactic bulge. If the survey efficiency is better than expected, we argue for
repeat observations of the same fields to improve photometric precision, or
covering additional fields to expand the stellar population reach if the
photometric precision for saturated stars is better than 1 mmag.
Asteroseismology is relatively insensitive to the timing of the observations
during the mission, and the prime red clump targets can be observed in a single
70 day campaign in any given field. Complementary stellar characterization,
particularly astrometry tied to the Gaia system, will also dramatically expand
the diagnostic power of asteroseismology. We also highlight synergies to Roman
GBTDS exoplanet science using transits and microlensing.Comment: Roman Core Community Survey White Paper, 3 pages, 4 figure
Asteroseismology with the Roman Galactic Bulge Time-Domain Survey
Asteroseismology has transformed stellar astrophysics. Red giant asteroseismology is a prime example, with oscillation periods and amplitudes that are readily detectable with time-domain space-based telescopes. These oscillations can be used to infer masses, ages and radii for large numbers of stars, providing unique constraints on stellar populations in our galaxy. The cadence, duration, and spatial resolution of the Roman galactic bulge time-domain survey (GBTDS) are well-suited for asteroseismology and will probe an important population not studied by prior missions. We identify photometric precision as a key requirement for realizing the potential of asteroseismology with Roman. A precision of 1 mmag per 15-min cadence or better for saturated stars will enable detections of the populous red clump star population in the Galactic bulge. If the survey efficiency is better than expected, we argue for repeat observations of the same fields to improve photometric precision, or covering additional fields to expand the stellar population reach if the photometric precision for saturated stars is better than 1 mmag. Asteroseismology is relatively insensitive to the timing of the observations during the mission, and the prime red clump targets can be observed in a single 70 day campaign in any given field. Complementary stellar characterization, particularly astrometry tied to the Gaia system, will also dramatically expand the diagnostic power of asteroseismology. We also highlight synergies to Roman GBTDS exoplanet science using transits and microlensing
Astro2020 science white paper:stellar physics and galactic archeology using asteroseismology in the 2020's
Astro2020 science white paper:stellar physics and galactic archeology using asteroseismology in the 2020's
Asteroseismology is the only observational tool in astronomy that can probe the interiors of stars, and is a benchmark method for deriving fundamental properties of stars and exoplanets. Over the coming decade, space-based and ground-based observations will provide a several order of magnitude increase of solar-like oscillators, as well as a dramatic increase in the number and quality of classical pulsator observations, providing unprecedented possibilities to study stellar physics and galactic stellar populations. In this white paper, we describe key science questions and necessary facilities to continue the asteroseismology revolution into the 2020's
The Fourteenth Data Release of the Sloan Digital Sky Survey: First Spectroscopic Data from the extended Baryon Oscillation Spectroscopic Survey and from the second phase of the Apache Point Observatory Galactic Evolution Experiment
The fourth generation of the Sloan Digital Sky Survey (SDSS-IV) has been in
operation since July 2014. This paper describes the second data release from
this phase, and the fourteenth from SDSS overall (making this, Data Release
Fourteen or DR14). This release makes public data taken by SDSS-IV in its first
two years of operation (July 2014-2016). Like all previous SDSS releases, DR14
is cumulative, including the most recent reductions and calibrations of all
data taken by SDSS since the first phase began operations in 2000. New in DR14
is the first public release of data from the extended Baryon Oscillation
Spectroscopic Survey (eBOSS); the first data from the second phase of the
Apache Point Observatory (APO) Galactic Evolution Experiment (APOGEE-2),
including stellar parameter estimates from an innovative data driven machine
learning algorithm known as "The Cannon"; and almost twice as many data cubes
from the Mapping Nearby Galaxies at APO (MaNGA) survey as were in the previous
release (N = 2812 in total). This paper describes the location and format of
the publicly available data from SDSS-IV surveys. We provide references to the
important technical papers describing how these data have been taken (both
targeting and observation details) and processed for scientific use. The SDSS
website (www.sdss.org) has been updated for this release, and provides links to
data downloads, as well as tutorials and examples of data use. SDSS-IV is
planning to continue to collect astronomical data until 2020, and will be
followed by SDSS-V.Comment: SDSS-IV collaboration alphabetical author data release paper. DR14
happened on 31st July 2017. 19 pages, 5 figures. Accepted by ApJS on 28th Nov
2017 (this is the "post-print" and "post-proofs" version; minor corrections
only from v1, and most of errors found in proofs corrected
Usage patterns, health, and nutritional status of long-term multiple dietary supplement users: a cross-sectional study
© 2007 Block et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution Licens
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