Last photograph taken on the surface of the moon by a human, Thursday, December 14, 1972 at 5:41 GMT by Apollo 17 astronaut Harrison Schmitt
An Earth-sized Planet around an M5 Dwarf Star at 22 pc
We report on the discovery of an Earth-sized transiting planet
(Rp=1.015±0.051R⊕) in a P=4.02 day orbit around K2-415 (EPIC
211414619), an M5V star at 22 pc. The planet candidate was first identified by
analyzing the light curve data by the K2 mission, and is here shown to exist in
the most recent data from TESS. Combining the light curves with the data
secured by our follow-up observations including high-resolution imaging and
near infrared spectroscopy with IRD, we rule out false positive scenarios,
finding a low false positive probability of 2×10−4. Based on IRD’s
radial velocities of K2-415, which were sparsely taken over three years, we
obtain the planet mass of 3.0±2.7M⊕ (Mp<7.5M⊕ at
95% confidence) for K2-415b. Being one of the lowest mass stars (≈0.16M⊙) known to host an Earth-sized transiting planet, K2-415 will be
an interesting target for further follow-up observations, including additional
radial velocity monitoring and transit spectroscopy.
Multibeam Blind Search of Targeted SETI Observations toward 33 Exoplanet Systems with FAST
The search for extraterrestrial intelligence (SETI) is to search for
technosignatures associated with extraterrestrial life, such as engineered
radio signals. In this paper, we apply the multibeam coincidence matching
(MBCM) strategy, and propose a new search mode based on the MBCM which we call
MBCM blind search mode. In our recent targeted SETI research, 33 exoplanet
systems are observed by the Five-hundred-meter Aperture Spherical radio
Telescope (FAST). With this blind search mode, we search for narrowband
drifting signals across 1.05−1.45 GHz in two orthogonal linear polarization
directions separately. There are two special signals, one of which can only be
detected by the blind search mode while the other can be found by both blind
and targeted search modes. This result reveals huge advantages of the new blind
search mode. However, we eliminate the possibility of the special signals being
ETI signals based on much evidence, such as the polarization, drift, frequency
and beam coverage characteristics. Our observations achieve an unprecedented
sensitivity and our work provides a deeper understanding to the polarization
analysis of extraterrestrial signals.
Mission Architecture to Reach and Operate at the Focal Region of the Solar Gravitational Lens
We present initial results of an engineering study on the feasibility of
a space mission to the focal region of the solar gravitational lens
(SGL). The mission goal is to conduct exoplanet imaging operations at
heliocentric distances in the range ∼548–900
astronomical units (AU). Starting at 547.6 AU from the sun, light from
an exoplanet located behind the sun is greatly amplified by the SGL. The
objective is to capture this light and use it for multipixel imaging of
an exoplanet up to 100 light years distant. Using a meter-class
telescope, one can capture the data needed to produce images of the
exoplanet with a surface resolution measured in tens of kilometers and
to identify signs of habitability. The data are acquired pixel by pixel
while moving an imaging spacecraft within the image. Given the long
duration of the mission, decades to reach 900 AU, we address an
architecture for the fastest possible transit time while reducing
mission risk and overall cost. The mission architecture implements solar
sailing technologies and in-space aggregation of modularized functional
units to form mission capable spacecraft. The study reveals elements of
such a challenging mission, but it is nevertheless found to be feasible
with technologies that are either extant or in active development.
the Small Magellanic Cloud, about 200k light years away and 19k light years long, it’s a dwarf galaxy companion to our own Milky Way; data taken remotely with the Heaven’s Mirror Observatory’s 10cm refractor telescope, edited by me
Using Hubble, researchers measure the mass of a single white dwarf for the first time
Of the trillions of stars scattered throughout the universe, one of the most common are the white dwarfs, which are the dormant, burned out, and leftover cores of low/medium mass stars. For decades, scientists have only measured the masses of white dwarfs within binary star systems. While these measurements provide insight into the true masses of white dwarfs, the measurements typically feature high amounts of uncertainty.
With help from the joint NASA/European Space Agency (ESA) Hubble Space Telescope, a team of researchers directly measured the mass of an isolated white dwarf outside of a binary star system. Found to be approximately 56% of the Sun’s mass, the team’s results agree with previous white dwarf mass predictions and provide insight into the evolutionary processes of dead stars.
Measurement of the axial vector form factor from antineutrino–proton scattering
Scattering of high energy particles from nucleons probes their
structure, as was done in the experiments that established the non-zero
size of the proton using electron beams.
The use of charged leptons as scattering probes enables measuring the
distribution of electric charges, which is encoded in the vector form
factors of the nucleon.
Scattering weakly interacting neutrinos gives the opportunity to
measure both vector and axial vector form factors of the nucleon,
providing an additional, complementary probe of their structure. The
nucleon transition axial form factor, FA, can be measured from neutrino scattering from free nucleons, νμn → μ−p and 𝜈¯𝜇𝑝→𝜇+𝑛, as a function of the negative four-momentum transfer squared (Q2). Up to now, FA(Q2) has been extracted from the bound nucleons in neutrino–deuterium scattering which requires uncertain nuclear corrections. Here we report the first high-statistics measurement, to our knowledge, of the 𝜈¯𝜇𝑝→𝜇+𝑛 cross-section from the hydrogen atom, using the plastic scintillator target of the MINERvA experiment, extracting FA from free proton targets and measuring the nucleon axial charge radius, rA,
to be 0.73 ± 0.17 fm. The antineutrino–hydrogen scattering presented
here can access the axial form factor without the need for nuclear
theory corrections, and enables direct comparisons with the increasingly
precise lattice quantum chromodynamics computations.
Finally, the tools developed for this analysis and the result presented
are substantial advancements in our capabilities to understand the
nucleon structure in the weak sector, and also help the current and
future neutrino oscillation experiments to better constrain neutrino interaction models.
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