Presence of red giant population in the foreground stellar sub-structure of the Small Magellanic Cloud

The eastern region of the Small Magellanic Cloud (SMC) is found to have a foreground stellar sub-structure, which is identified as a distance bimodality (∼ 12 kpc apart) in the previous studies using Red Clump (RC) stars. Interestingly, studies of Red Giant Branch (RGB) stars in the eastern SMC indicate a bimodal radial velocity (RV) distribution. In this study, we investigate the connection between these two bimodal distributions to better understand the nature and origin of the foreground stellar sub-structure in the eastern SMC. We use the Gaia EDR3 astrometric data and archival RV data of RGB stars for this study. We found a bimodal RV distribution of RGB stars (separated by ∼ 35–45 km s−1) in the eastern and south-western (SW) outer regions. The observed proper motion values of the lower and higher RV RGB components in the eastern regions are similar to those of the foreground and main-body RC stars respectively. This suggests that the two RGB populations in the eastern region are separated by a similar distance as those of the RC stars, and the RGB stars in the lower RV component are part of the foreground sub-structure. Based on the differences in the distance and RV of the two components, we estimated an approximate time of formation of this sub-structure as 307 ± 65 Myr ago. This is comparable with the values predicted by simulations for the recent epoch of tidal interaction between the Magellanic Clouds. Comparison of the observed properties of RGB stars, in the outer SW region, with N-body simulations shows that the higher RV component in the SW region is at a farther distance than the main body, indicating the presence of a stellar Counter-Bridge in the SW region of the SMC.

Water on Mars: The Real Deal

This chapter talks about the astronomers that have solved some of the riddles of how much water Mars had and still has, a century and a half after William Huggins first proved that Mars had water. It highlights that Mars' water was no longer in the liquid state on the surface as the planet had become much dryer after billions of years. It also examines significant evidence that strongly suggests that Mars experienced a more recent epoch when water carved valleys and was formed from melting snow and ice that flowed slowly into and out of chains of lakes. The chapter describes one of Mars' lakes that appears to have been widespread both north and south of the Martian equator, containing more water than Lake Ontario. It discusses Mars' layered ice deposits at the north and south polar caps, in which a thin layer is deposited each Martian winter and then sublimates in Martian spring.

Climatic Shift of the Tropical Cyclone Activity Affecting Vietnam’s Coastal Region

This study examines the climatic shift of the tropical cyclone (TC) frequency affecting Vietnam’s coastal region during 1975–2014. By separating TC databases into two different 20-yr epochs, it is found that there is a consistent increase in both the number of strong TCs and the number of TC occurrences during the recent epoch (1995–2014) as compared with the reference epoch (1975–94) across different TC databases. This finding suggests that not only the number of strong TCs but also the lifetime of strong TCs affecting Vietnam’s coastal region has been recently increasing as compared with the reference epoch from 1975 to 1994. To understand the physical connection of these shifts in the TC frequency and duration, large-scale conditions obtained from reanalysis data are analyzed. Results show that meridional surface temperature gradient (STG) during the recent epoch is substantially larger than that during 1975–94. Such an increase in the meridional STG is important because it is potentially linked to the increase in large-scale vertical wind shear as well as the reduced intensity of summer monsoon in the South China Sea between the two epochs.

Special Issue on Intelligent Processing on Image and Optical Information

Intelligent image and optical information processing have paved the way for the recent epoch of new intelligence and information era [...]

Radio observations of supernova remnant G1.9+0.3

ABSTRACT We present 1–10 GHz radio continuum flux density, spectral index, polarization, and rotation measure (RM) images of the youngest known Galactic supernova remnant (SNR) G1.9+0.3, using observations from the Australia Telescope Compact Array. We have conducted an expansion study spanning eight epochs between 1984 and 2017, yielding results consistent with previous expansion studies of G1.9+0.3. We find a mean radio continuum expansion rate of (0.78 ± 0.09) per cent yr−1 (or ∼8900 km s−1 at an assumed distance of 8.5 kpc), although the expansion rate varies across the SNR perimetre. In the case of the most recent epoch between 2016 and 2017, we observe faster-than-expected expansion of the northern region. We find a global spectral index for G1.9+0.3 of −0.81 ± 0.02 (76 MHz–10 GHz). Towards the northern region, however, the radio spectrum is observed to steepen significantly (∼−1). Towards the two so-called (east and west) ‘ears’ of G1.9+0.3, we find very different RM values of 400–600 and 100–200 rad m2, respectively. The fractional polarization of the radio continuum emission reaches (19 ± 2) per cent, consistent with other, slightly older, SNRs such as Cas A.

An Assessment of Drought in Mannar District, Sri Lanka

Due to recent climate changes and variability the frequency of occurrence and intensity of extreme climatic events such as flood, drought, etc. are increasing significantly in Sri Lanka. The main objectives of the study are to analyze the annual and seasonal rainfall variability in the last 147years from 1871-2018 with particular reference to drought and to assess the occurrence of droughts and its intensity and the impacts of drought on agriculture. For this secondary and primary data have been used. The long-term average annual rainfall of Mannar show the decreasing trend (r2= 0.0158), particularly in recent epochs higher negative anomalies of rainfall were found, as a results frequent occurrence of droughts or dry spells have been occurred. The rainfall anomaly results reveal that, out of 147years of the data period about 47years were experienced as drought and its probability is P=0.320. Accordingly, once in four to five years a drought could be possible. However, in the recent epoch of 1991-2018, higher number of droughts occurred than the any other epochs and its epochal probability is higher (P=0.40) than the normal, which indicate the effect of recent climate change.

Evolution of the main geomorphological structure of the Holocene Kuban river delta

In the recent epoch the Kuban River delta is characterized by little distributary with low zone of lagoons and flooded areas. This accumulative plain includes different types of mesorelief such as longshore bar, channel bank, liman, plavni and channel distributaries. There are three huge geomorphological types of Kuban delta: old, young deltas and Kuban-Taman region. The main differences between them are diverse geomorphological levels, evolution of marine and fluvial forms and incomplete geomorphological development. The relief of the Kuban delta is Holocene. The main factors of its formation were large-scale fluctuations of the Azov-Black Sea basin, the flow of water and sediment of the Kuban River and its distribution in area. In the history of the development of the modern relief of the Kuban delta, there are three stages (epochs). The first is the Bugaz stage of the Holocene transgression (9.57.9 ka), when the relief of the old delta was formed. In the second stage of the Holocene transgression (Vityazevskaya, Kalamitskaya, and Dzhemetyan stages), a transitional type of relief was formed in the area adjacent to the floods of the young delta and the old delta with the formation of large buried bars. In the third stage, the systems of modern estuaries and plavni were formed, separated from the sea by a modern coastal bar.

LONTARAK LATOA SALAH SATU SUMBER INFORMASI TENTANG HUKUM BAGI MASYARAKAT BUGIS

Especial source of the august value complete in lontarak. Thinker of is so-called in it lay open life image and ideas owning philosophy value which with quality. If that idea arrive and known by next generation of course will penetrate life of society, even come up with this recent epoch. Value having the character of that moral for example have been laid open by To Riolo (former sage), that four kinds of deed him both for having precedence over. First, thinking of all good utterance and wise deed of everybody. second, Searching way out of idea concept swiftly and precisely, that intention which is wrong to be barricaded to be realized by goodness in words and also in behaviour. Third, bearing with when befalled by accident, but gaze to find its solution. Fourth, soft in saying word so that faced always in a condition peace. Keyword : Lontarak, Bugis AbstrakSumber utama nilai luhur tersebut lengkap dalam lontarak. Pemikir yang disebut di dalamnya mengungkapkan ide-ide dan citra kehidupan yang memiliki nilai filsafat yang berkualitas. Apabila ide itu tiba dan diketahui oleh generasi berikutnya tentu akan menembus kehidupan masyarakat, bahkan sampai pada zaman mutakhir ini. Nilai yang bersifat moral itu antara lain telah diungkapkan oleh To Riolo (orang bijaksana dahulu), bahwa empat macamnya perbuatan baik yang harus didahulukan. Pertama, memikirkan semua ucapan baik dan perbuatan bijak dari semua orang. Kedua, Mencari jalan keluar dari konsep pemikiran dengan cepat dan tepat, bahwa niat yang salah dibendung untuk diwujudkan baik dalam kata-kata maupun dalam tingkah laku. Ketiga, bersabar bila ditimpa musibah, namun merenung untuk menemukan solusinya. Keempat, berlemah-lembut dalam bertutur kata agar yang dihadapi selalu dalam kondisi damai.Kata kunci : Lontarak, Bugis

Regional Changes in the Interannual Variability of U.S. Warm Season Precipitation

Intensification of regional springtime precipitation variability over the United States and the role of North American low-level jets (NALLJs) are investigated for the 1950–2010 period. The analysis reveals that the primary modes of NALLJ fluctuations are related to the strengthening of AMJ precipitation variability over the northern Great Plains and southeastern United States during the last 60 years. Examination of the epochal change in NALLJ variations shows a stronger connectivity to SST variability during 1980–2010 than in the 1950–79 period. In the context of the first three NALLJ variability modes it appears that the role of decadal SST variations (NALLJ mode 1) and the recent emergence of tropical Pacific connectivity (NALLJ modes 1 and 2) via SST-induced atmospheric heating and large-scale circulation changes may act to strengthen and spatially shift the NALLJ variability modes southward and/or eastward, intensifying regional precipitation variability in the recent epoch. Although notable NALLJ variability also exists in the earlier epoch, the upper-level height field is significantly lacking in meridional gradients, leading to weak upper-level zonal wind anomalies over the United States and diminished NALLJ variability. Conversely, the intensified and spatially shifted upper-level height anomaly in the recent epoch produces enhanced meridional height gradients in all three modes, strengthening NALLJ variability—highlighting that seemingly subtle shifts in hemispheric-scale atmospheric circulation changes can have important impacts on regional climate variability and change.

Decadal changes from a multi-temporal glacier inventory of Svalbard

We present a multi-temporal digital inventory of Svalbard glaciers with the most recent from the late 2000s containing 33 775 km2 of glaciers covering 57% of the total land area of the archipelago. At present, 68% of the glacierized area of Svalbard drains through tidewater glaciers that have a total terminus width of ~ 740 km. The glacierized area over the entire archipelago has decreased by an average of 80 km2 a−1 over the past ~ 30 yr, representing a reduction of 7%. For a sample of ~ 400 glaciers (10 000 km2) in the south and west of Spitsbergen, three digital inventories are available from the 1930/60s, 1990 and 2007 from which we calculate average changes during 2 epochs. In the more recent epoch, the terminus retreat was larger than in the earlier epoch, while area shrinkage was smaller. The contrasting pattern may be explained by the decreased lateral wastage of the glacier tongues. Retreat rates for individual glaciers show a mix of accelerating and decelerating trends, reflecting the large spatial variability of glacier types and climatic/dynamic response times in Svalbard. Lastly, retreat rates estimated by dividing glacier area changes by the tongue width are larger than centerline retreat due to a more encompassing frontal change estimate with inclusion of lateral area loss.