Predicting the Amplitude of a Solar Cycle Using the North-South Asymmetry in the Previous Cycle: II. An Improved Prediction for Solar Cycle~24

Recently, using Greenwich and Solar Optical Observing Network sunspot group data during the period 1874-2006, (Javaraiah, MNRAS, 377, L34, 2007: Paper I), has found that: (1) the sum of the areas of the sunspot groups in 0-10 deg latitude interval of the Sun's northern hemisphere and in the time-interval of -1.35 year to +2.15 year from the time of the preceding minimum of a solar cycle n correlates well (corr. coeff. r=0.947) with the amplitude (maximum of the smoothed monthly sunspot number) of the next cycle n+1. (2) The sum of the areas of the spot groups in 0-10 deg latitude interval of the southern hemisphere and in the time-interval of 1.0 year to 1.75 year just after the time of the maximum of the cycle n correlates very well (r=0.966) with the amplitude of cycle n+1. Using these relations, (1) and (2), the values 112 + or - 13 and 74 + or -10, respectively, were predicted in Paper I for the amplitude of the upcoming cycle 24. Here we found that in case of (1), the north-south asymmetry in the area sum of a cycle n also has a relationship, say (3), with the amplitude of cycle n+1, which is similar to (1) but more statistically significant (r=0.968) like (2). By using (3) it is possible to predict the amplitude of a cycle with a better accuracy by about 13 years in advance, and we get 103 + or -10 for the amplitude of the upcoming cycle 24. However, we found a similar but a more statistically significant (r=0.983) relationship, say (4), by using the sum of the area sum used in (2) and the north-south difference used in (3). By using (4) it is possible to predict the amplitude of a cycle by about 9 years in advance with a high accuracy and we get 87 + or - 7 for the amplitude of cycle 24.Comment: 21 pages, 7 figures, Published in Solar Physics 252, 419-439 (2008

TESS spots a hot Jupiter with an inner transiting Neptune

Stars and planetary system

It takes two planets in resonance to tango around K2-146

Stars and planetary system

K2-280 b - a low density warm sub-Saturn around a mildly evolved star

Stars and planetary system

Variation of abundance and demographic structure of the introduced pumpkinseed, Lepomis gibbosus (Actinopterygii: Perciformes: Centrarchidae), in relation to littoral habitats and water body use

Background. The pumpkinseed, Lepomis gibbosus (L.), is one of 23 introduced fish species in Bulgarian freshwaters. With this study we attempt to contribute to clarifying the factors that effect pumpkinseed abundance and demographic structure in water bodies differing in macro- and microhabitat parameters. Materials and methods. Fish were collected during the breeding period of pumpkinseed (May–June 2010) by minnow traps arranged in 31 sites in the littoral zone of 13 fresh water bodies (former- and active sand-pit lakes, reservoirs, adaptive ponds of refineries). Demographic structure (length and age) and abundance (Catch Per Unit Effort; CPUEN; fish per trap per hour) of pumpkinseeds from different sites were compared to provide information about ecological requirements of this species. Results. L. gibbosus dominated at 24 sites and comprised 86.7% of all fish caught. The mean pumpkinseed abundance was 6.35 ± 7.2 fish per trap per hour (mean ± SD). Pumpkinseeds were most numerous in the littoral zones of the former sand-pit lakes, where pumpkinseed’s CPUEN achieved values of 20 fish per trap per hour. Water body use had a significant effect on pumpkinseed abundance and the statistical analyses revealed that the littoral zones in the active sand-pit lakes were characterized by the lowest number of pumpkinseeds than the other types. Microhabitat parameters such as silt and sand bottom substrate also significantly affected pumpkinseeds abundance, size, and age, while gravel significantly affected body length but not abundance and age. Aquatic vegetation also had a significant impact on the abundance and at sites with dense vegetation pumpkinseeds were more abundant than at the sites with sparse vegetation. At the sites where piscivore fish occurred, the mean length and mean age of pumpkinseed were lower. Conclusion. Human activities facilitate establishment of the pumpkinseed population, mainly by extending suitable breeding places for pumpkinseed and eliminating its natural competitors and predators. Some parameters as sand or silt bottoms in littoral area and dense submerged vegetation may use as indicator of suitable conditions for pumpkinseed

Greening of the brown-dwarf desert. EPIC 212036875b: a 51 MJ object in a 5-day orbit around an F7 V star

Context. Although more than 2000 brown dwarfs have been detected to date, mainly from direct imaging, their characterisation is difficult due to their faintness and model-dependent results. In the case of transiting brown dwarfs, however, it is possible to make direct high-precision observations. Aims: Our aim is to investigate the nature and formation of brown dwarfs by adding a new well-characterised object, in terms of its mass, radius and bulk density, to the currently small sample of less than 20 transiting brown dwarfs. Methods: One brown dwarf candidate was found by the KESPRINT consortium when searching for exoplanets in the K2 space mission Campaign 16 field. We combined the K2 photometric data with a series of multicolour photometric observations, imaging, and radial velocity measurements to rule out false positive scenarios and to determine the fundamental properties of the system. Results: We report the discovery and characterisation of a transiting brown dwarf in a 5.17-day eccentric orbit around the slightly evolved F7 V star EPIC 212036875. We find a stellar mass of 1.15 ± 0.08 M&sun;, a stellar radius of 1.41 ± 0.05 R&sun;, and an age of 5.1 ± 0.9 Gyr. The mass and radius of the companion brown dwarf are 51 ± 2 MJ and 0.83 ± 0.03 RJ, respectively, corresponding to a mean density of 108-13+15 g cm-3. Conclusions: EPIC 212036875 b is a rare object that resides in the brown-dwarf desert. In the mass-density diagram for planets, brown dwarfs, and stars, we find that all giant planets and brown dwarfs follow the same trend from 0.3 MJ to the turn-over to hydrogen burning stars at 73 MJ. EPIC 212036875 b falls close to the theoretical model for mature H/He dominated objects in this diagram as determined by interior structure models. We argue that EPIC 212036875 b formed via gravitational disc instabilities in the outer part of the disc, followed by a quick migration. Orbital tidal circularisation may have started early in its history for a brief period when the brown dwarf's radius was larger. The lack of spin-orbit synchronisation points to a weak stellar dissipation parameter (Q*' ≳ 108), which implies a circularisation timescale of ≳23 Gyr, or suggests an interaction between the magnetic and tidal forces of the star and the brown dwarf. Table 2 is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/628/A64This work is done under the framework of the KESPRINT collaboration (http://kesprint.science). KESPRINT is an international consortium devoted to the characterisation and research of exoplanets discovered with space-based missions. Associated Articles Source Paper     Catalog Description   &#160