44 research outputs found
Measurement of the Muon Decay Parameter delta
The muon decay parameter delta has been measured by the TWIST collaboration.
We find delta = 0.74964 +- 0.00066(stat.) +- 0.00112(syst.), consistent with
the Standard Model value of 3/4. This result implies that the product Pmuxi of
the muon polarization in pion decay, Pmu, and the muon decay parameter xi falls
within the 90% confidence interval 0.9960 < Pmuxi < xi < 1.0040. It also has
implications for left-right-symmetric and other extensions of the Standard
Model.Comment: Extended to 5 pages. Referee's comments answere
Supernova search with active learning in ZTF DR3
We provide the first results from the complete SNAD adaptive learning
pipeline in the context of a broad scope of data from large-scale astronomical
surveys. The main goal of this work is to explore the potential of adaptive
learning techniques in application to big data sets. Our SNAD team used Active
Anomaly Discovery (AAD) as a tool to search for new supernova (SN) candidates
in the photometric data from the first 9.4 months of the Zwicky Transient
Facility (ZTF) survey, namely, between March 17 and December 31 2018 (58194 <
MJD < 58483). We analysed 70 ZTF fields at a high galactic latitude and
visually inspected 2100 outliers. This resulted in 104 SN-like objects being
found, 57 of which were reported to the Transient Name Server for the first
time and with 47 having previously been mentioned in other catalogues, either
as SNe with known types or as SN candidates. We visually inspected the
multi-colour light curves of the non-catalogued transients and performed
fittings with different supernova models to assign it to a probable photometric
class: Ia, Ib/c, IIP, IIL, or IIn. Moreover, we also identified unreported
slow-evolving transients that are good superluminous SN candidates, along with
a few other non-catalogued objects, such as red dwarf flares and active
galactic nuclei. Beyond confirming the effectiveness of human-machine
integration underlying the AAD strategy, our results shed light on potential
leaks in currently available pipelines. These findings can help avoid similar
losses in future large-scale astronomical surveys. Furthermore, the algorithm
enables direct searches of any type of data and based on any definition of an
anomaly set by the expert.Comment: 22 pages with appendix, 12 figures, 2 tables, accepted for
publication in Astronomy and Astrophysic
Registration of the quantum state of a single photon to create a satellite quantum network
Artificial satellites employed as trusted nodes can increase the distance between two parties to establish quantum key distribution (QKD), unlike fiber based communication lines that are limited up to a few hundred kilometers. This report summarises our progress on a ground receiver for satellite QKD and its tracking receiving system (TRS). The authors demonstrate the operation of the TRS in practice and achieve standard tracking error of 1.4/Ltrad observing four satellites over 80% of the time they were available. The optical signal, which was the sunlight reflected of low Earth orbit satellites, was attenuated to a single photon level and was detected effectively using avalanche single photon detectors. The authors have thus proved that the developed system is capable of stable reception of quantum signal from a satellite. © Published under licence by IOP Publishing Ltd.This work is supported by Russian Science Foundation (grant No. 17-71-20146)
Measurement of the Michel Parameter in Muon Decay
The TWIST Collaboration has measured the Michel parameter in normal
muon decay, . In the Standard Model,
= 3/4. Deviations from this value require mixing of left- and
right-handed muon and electron couplings in the muon-decay Lagrangian. We find
= 0.75080 0.00044(stat.) 0.00093(syst.) 0.00023, where
the last uncertainty represents the dependence of on the Michel
parameter . This result sets new limits on the mixing angle in
left-right symmetric models.Comment: 4 pages, 3 figures, submitted to PR
Discovery of a young low-mass brown dwarf transiting a fast-rotating F-type star by the Galactic Plane eXoplanet (GPX) survey
We announce the discovery of GPX-1 b, a transiting brown dwarf with a mass of
and a radius of
, the first sub-stellar object discovered by the Galactic
Plane eXoplanet (GPX) survey. The brown dwarf transits a moderately bright (
= 12.3 mag) fast-rotating F-type star with a projected rotational velocity
km/s. We use the isochrone placement algorithm to
characterize the host star, which has effective temperature K,
mass , radius
and approximate age Gyr. GPX-1 b has an orbital period
of 1.75 d, and a transit depth of %. We describe the GPX
transit detection observations, subsequent photometric and
speckle-interferometric follow-up observations, and SOPHIE spectroscopic
measurements, which allowed us to establish the presence of a sub-stellar
object around the host star. GPX-1 was observed at 30-min integrations by TESS
in Sector 18, but the data is affected by blending with a 3.4 mag brighter star
42 arcsec away. GPX-1 b is one of about two dozen transiting brown dwarfs known
to date, with a mass close to the theoretical brown dwarf/gas giant planet mass
transition boundary. Since GPX-1 is a moderately bright and fast-rotating star,
it can be followed-up by the means of Doppler tomography.Comment: 13 pages, 13 figures, accepted to MNRAS in May 202
Анализ содержания 8-оксо-2'-дезоксигуанозина в ДНК клеток мозга крыс при изучении защитного действия кортексина
The protective effect of cortexin was investigated with the use of acoustic stress hemorrhagic stroke model. A significant decrease of 8-oxo-2'-deoxyguanosine to 2'-deoxyguanosine ratio in the DNA molecule was shown using brain slices of cortexin treated Krushinsky-Molodkina rats.В работе изучено влияние защитного действия препарата кортексин на мозг крыс линии Крушинского-Молодкиной в условиях экспериментального геморрагического инсульта, вызван-ного акустическим стрессом. Показано значительное уменьшение отношения 8-оксо-2'-дезокси-гуанозина к 2'-дезоксигуанозину в ДНК клеток мозга крыс при применении кортексина
Radial Distribution of the Dust Comae of Comets 45P/Honda–Mrkos–Pajdusáková and 46P/Wirtanen
There was an unprecedented opportunity to study the inner dust coma environments, where the dust and gas are not entirely decoupled, of comets 45P/Honda–Mrkos–Pajdusáková (45P/HMP) from 2016 December 26 to 2017 March 15, and 46P/Wirtanen from 2018 November 10 to 2019 February 13, both in visible wavelengths. The radial profile slopes of these comets were measured in the R and HB-BC filters most representative of dust, and deviations from a radially expanding coma were identified as significant. The azimuthally averaged radial profile slope of comet 45P/HMP gradually changes from −1.81 ± 0.20 at 5.24 days preperihelion to −0.35 ± 0.16 at 74.41 days postperihelion. Contrastingly, the radial profile slope of 46P/Wirtanen stays fairly constant over the observed time period at −1.05 ± 0.05. Additionally, we find that the radial profile of 46P/Wirtanen is azimuthally dependent on the sky-plane-projected solar position angle, while that of 45P/HMP is not. These results suggest that comets 45P/HMP and 46P/Wirtanen have vastly different coma dust environments and that their dust expansion properties are distinct. As evident from these two comets, well-resolved inner comae are vital for detailed characterization of dust environments. © 2022. The Author(s). Published by the American Astronomical Society.We would like to thank everyone who participated in the data-gathering process. This includes all students from the Lunar and Planetary Laboratory course PTYS 495B/595B (Fall 2018). We would also like to thank the additional organizers of the 4*P Campaign: Matthew Knight (United States Naval Academy) and Tony Farnham (University of Maryland). We would like the thank the Steward Observatory technical staff for the amount of time they dedicated to this project. Finally, we would like to thank the SSO grant No. NNX16A670G (Walt Harris) and the NESSF grant No. 80NSSC18K1241 (Cassandra Lejoly; P.I.: Walt Harris) for allowing this work to be completed. We would also like to thank the Slovak Academy of Sciences grant No. VEGA 2/ 0023/18 (Oleksandra Ivanova) and the Slovak Research and Development Agency under the Contract no. APVV-19-0072 (Oleksandra Ivanova)
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The First Post-Kepler Brightness Dips of KIC 8462852
We present a photometric detection of the first brightness dips of the unique
variable star KIC 8462852 since the end of the Kepler space mission in 2013
May. Our regular photometric surveillance started in October 2015, and a
sequence of dipping began in 2017 May continuing on through the end of 2017,
when the star was no longer visible from Earth. We distinguish four main 1-2.5%
dips, named "Elsie," "Celeste," "Skara Brae," and "Angkor", which persist on
timescales from several days to weeks. Our main results so far are: (i) there
are no apparent changes of the stellar spectrum or polarization during the
dips; (ii) the multiband photometry of the dips shows differential reddening
favoring non-grey extinction. Therefore, our data are inconsistent with dip
models that invoke optically thick material, but rather they are in-line with
predictions for an occulter consisting primarily of ordinary dust, where much
of the material must be optically thin with a size scale <<1um, and may also be
consistent with models invoking variations intrinsic to the stellar
photosphere. Notably, our data do not place constraints on the color of the
longer-term "secular" dimming, which may be caused by independent processes, or
probe different regimes of a single process
Another Shipment of Six Short-Period Giant Planets from TESS
We present the discovery and characterization of six short-period, transiting
giant planets from NASA's Transiting Exoplanet Survey Satellite (TESS) --
TOI-1811 (TIC 376524552), TOI-2025 (TIC 394050135), TOI-2145 (TIC 88992642),
TOI-2152 (TIC 395393265), TOI-2154 (TIC 428787891), & TOI-2497 (TIC 97568467).
All six planets orbit bright host stars (8.9 <G< 11.8, 7.7 <K< 10.1). Using a
combination of time-series photometric and spectroscopic follow-up observations
from the TESS Follow-up Observing Program (TFOP) Working Group, we have
determined that the planets are Jovian-sized (R = 1.00-1.45 R),
have masses ranging from 0.92 to 5.35 M, and orbit F, G, and K stars
(4753 T 7360 K). We detect a significant orbital eccentricity
for the three longest-period systems in our sample: TOI-2025 b (P = 8.872 days,
= ), TOI-2145 b (P = 10.261 days, =
), and TOI-2497 b (P = 10.656 days, =
). TOI-2145 b and TOI-2497 b both orbit subgiant host
stars (3.8 g 4.0), but these planets show no sign of inflation
despite very high levels of irradiation. The lack of inflation may be explained
by the high mass of the planets; M (TOI-2145
b) and M (TOI-2497 b). These six new discoveries
contribute to the larger community effort to use {\it TESS} to create a
magnitude-complete, self-consistent sample of giant planets with
well-determined parameters for future detailed studies.Comment: 20 Pages, 6 Figures, 8 Tables, Accepted by MNRA
The First Post-Kepler Brightness Dips of KIC 8462852
We present a photometric detection of the first brightness dips of the unique variable star KIC 8462852 since the end of the Kepler space mission in 2013 May. Our regular photometric surveillance started in October 2015, and a sequence of dipping began in 2017 May continuing on through the end of 2017, when the star was no longer visible from Earth. We distinguish four main 1-2.5% dips, named "Elsie," "Celeste," "Skara Brae," and "Angkor", which persist on timescales from several days to weeks. Our main results so far are: (i) there are no apparent changes of the stellar spectrum or polarization during the dips; (ii) the multiband photometry of the dips shows differential reddening favoring non-grey extinction. Therefore, our data are inconsistent with dip models that invoke optically thick material, but rather they are in-line with predictions for an occulter consisting primarily of ordinary dust, where much of the material must be optically thin with a size scale <<1um, and may also be consistent with models invoking variations intrinsic to the stellar photosphere. Notably, our data do not place constraints on the color of the longer-term "secular" dimming, which may be caused by independent processes, or probe different regimes of a single process