Do Kepler superflare stars really include slowly-rotating Sun-like stars ? - Results using APO 3.5m telescope spectroscopic observations and Gaia-DR2 data -

We report the latest view of Kepler solar-type (G-type main-sequence) superflare stars, including recent updates with Apache Point Observatory (APO) 3.5m telescope spectroscopic observations and Gaia-DR2 data. First, we newly conducted APO3.5m spectroscopic observations of 18 superflare stars found from Kepler 1-min time cadence data. More than half (43 stars) are confirmed to be "single" stars, among 64 superflare stars in total that have been spectroscopically investigated so far in this APO3.5m and our previous Subaru/HDS observations. The measurements of $v\sin i$ (projected rotational velocity) and chromospheric lines (Ca II H\&K and Ca II 8542\AA) support the brightness variation of superflare stars is caused by the rotation of a star with large starspots. We then investigated the statistical properties of Kepler solar-type superflare stars by incorporating Gaia-DR2 stellar radius estimates. As a result, the maximum superflare energy continuously decreases as the rotation period $P_{\mathrm{rot}}$ increases. Superflares with energies $\lesssim 5\times10^{34}$ erg occur on old, slowly-rotating Sun-like stars ($P_{\mathrm{rot}}\sim$25 days) approximately once every 2000--3000 years, while young rapidly-rotating stars with $P_{\mathrm{rot}}\sim$ a few days have superflares up to $10^{36}$ erg. The maximum starspot area does not depend on the rotation period when the star is young, but as the rotation slows down, it starts to steeply decrease at $P_{\mathrm{rot}}\gtrsim$12 days for Sun-like stars. These two decreasing trends are consistent since the magnetic energy stored around starspots explains the flare energy, but other factors like spot magnetic structure should also be considered.Comment: 71 pages, 31 figures, 10 tables. Accepted for publication in The Astrophysical Journal (on March 29, 2019

Starspot Mapping with Adaptive Parallel Tempering. II. Application to TESS Data for M-dwarf Flare Stars AU Microscopii, YZ Canis Minoris, and EV Lacertae

Starspots and stellar flares are indicators of stellar magnetic activity. The magnetic energy stored around spots is thought to be the origin of flares, but the connection is not completely understood. To investigate the relation between spot locations deduced from light curves and the occurrence of flares therein, we perform starspot modeling for the TESS light curves of three M-dwarf flare stars, AU Mic, YZ CMi, and EV Lac, using the code implemented in Paper I. The code enables us to deduce multiple stellar/spot parameters by the adaptive parallel tempering algorithm efficiently. We find that flare occurrence frequency is not necessarily correlated with the rotation phases of the light curve for each star. The result of starspot modeling shows that any spot is always visible to the line of sight in all phases, and we suggest that this can be one of the reasons why there is no or low correlation between rotation phases and flare frequency. In addition, the amplitude and shape of the light curve for AU Mic and YZ CMi have varied in two years between different TESS cycles. The result of starspot modeling suggests that this can be explained by the variations of spot size and latitude

Starspot mapping with adaptive parallel tempering I: Implementation of computational code

Starspots are thought to be regions of locally strong magnetic fields, similar to sunspots, and they can generate photometric brightness modulations. To deduce stellar and spot properties, such as spot emergence and decay rates, we implement computational code for starspot modeling. It is implemented with an adaptive parallel tempering algorithm and an importance sampling algorithm for parameter estimation and model selection in the Bayesian framework. For evaluating the performance of the code, we apply it to synthetic light curves produced with 3 spots. The light curves are specified in the spot parameters, such as the radii, intensities, latitudes, longitudes, and emergence/decay durations. The spots are circular with specified radii and intensities relative to the photosphere, and the stellar differential rotation coefficient is also included in the light curves. As a result, stellar and spot parameters are uniquely deduced. The number of spots is correctly determined: the 3-spot model is preferable because the model evidence is much greater than that of 2-spot models by orders of magnitude and more than that of 4-spot model by a more modest factor, whereas the light curves are produced to have 2 or 1 local minimum during one equatorial rotation period by adjusting the values of longitude. The spot emergence and decay rates can be estimated with error less than an order of magnitude, considering the difference of the number of spots.Comment: 27 pages, 14 figures, 2 tables, accepted for publication in Ap

A manual sequence method of peptides and phosphopeptides using 4-(1\u27-cyanoisoindolyl)phenylisothiocyanate.

A method for sequence analysis and identification of phosphoamino acids in peptides based on high performance liquid chromatography (HPLC) is described. The peptides were derivatized with an Edman type reagent, 4-(1\u27-cyanoisoindolyl)phenylisothiocyanate (CIPIC) and subsequently cleaved to generate stable and fluorescent 4-(1\u27-cyanoisoindolyl)phenylthiazolinone (CIP-TZ)-amino acids. Several experimental factors that affected derivatization on membranes were examined. Under the optimized conditions, the CIP-TZ derivatives of Try(p), Thr(p) and Ser(p) were obtained and separated from their parent amino acids with baseline resolution using an isocratic elution system. Up to the 4th residue of phosphorylated pentapeptides was successfully identified, whereas phosphoamino acid residues could not be detected by the conventional procedure using phenylisothiocyanate (PITC). The results demonstrated the potential of CIPIC as a derivatization reagent for peptide sequencing and the applicability of the method for the study and identification of phosphoamino acids in peptides

Penggunaan Tenaga Kerja Asing Oleh Perseroan Terbatas Penanam Modal Asing Yang Berinvestasi Di Indonesia

A number of foreign workers who are currently working in Indonesia is not in accordance with the legislation that exists. The foreign workers doing menial jobs and do not have immigration documents are complete. They are working on a number of foreign investors in a number of business sectors, especially in construction and infrastructure. The type of research that is done is the normative legal research i.e. Research which focuses on positive form of legal norms and regulations. Types of data used include primary law, secondary legal materials and legal materials tertiary. The use of foreign labor by a limited liability foreign investors who invest in Indonesia must comply with the legislation that exists. The foreign workers are only allowed to occupy positions as commissioners, directors, and experts who are accompanied by a complete immigration administrative documents

Temporal Evolution of Spatially-Resolved Individual Star Spots on a Planet-Hosting Solar-type Star: Kepler 17

Star spot evolution is visible evidence of the emergence/decay of the magnetic field on stellar surface, and it is therefore important for the understanding of the underlying stellar dynamo and consequential stellar flares. In this paper, we report the temporal evolution of individual star spot area on the hot-Jupiter-hosting active solar-type star Kepler 17 whose transits occur every 1.5 days. The spot longitude and area evolution are estimated (1) from the stellar rotational modulations of Kepler data and (2) from the brightness enhancements during the exoplanet transits caused by existence of large star spots. As a result of the comparison, number of spots, spot locations, and the temporal evolution derived from the rotational modulations is largely different from those of in-transit spots. We confirm that although only two light curve minima appear per rotation, there are clearly many spots present on the star. We find that the observed differential intensity changes are sometimes consistent with the spot pattern detected by transits, but they sometimes do not match with each other. Although the temporal evolution derived from the rotational modulation differs from those of in-transit spots to a certain degree, the emergence/decay rates of in-transit spots are within an order of magnitude of those derived for sunspots as well as our previous research based only on rotational modulations. This supports a hypothesis that the emergence/decay of sunspots and extremely-large star spots on solar-type stars occur through the same underlying processes.Comment: 37 pages, 12 figures, 1 table. Accepted for publication in The Astrophysical Journa