Evidence for fresh frost layer on the bare nucleus of comet Hale--Bopp at 32 AU distance

Here we report that the activity of comet Hale--Bopp ceased between late 2007 and March, 2009, at about 28 AU distance from the Sun. At that time the comet resided at a distance from the Sun that exceeded the freeze-out distance of regular comets by an order of magnitude. A Herschel Space Observatory PACS scan was taken in mid-2010, in the already inactive state of the nucleus. The albedo has been found to be surprisingly large (8.1$\pm$0.9%{}), which exceeds the value known for any other comets. With re-reduction of archive HST images from 1995 and 1996, we confirm that the pre-perihelion albedo resembled that of an ordinary comet, and was smaller by a factor of two than the post-activity albedo. Our further observations with the Very Large Telescope (VLT) also confirmed that the albedo increased significantly by the end of the activity. We explain these observations by proposing gravitational redeposition of icy grains towards the end of the activity. This is plausible for such a massive body in a cold environment, where gas velocity is lowered to the range of the escape velocity. These observations also show that giant comets are not just the upscaled versions of the comets we know but can be affected by processes that are yet to be fully identified.Comment: 7 pages, 6 figures, accepted for publication in Ap

Developments in sovereign bond issuance in the Central and Eastern European region after the Lehman collapse

This paper focuses on the impact of the financial and economic crisis of 2008–2009 on the issuance of sovereign debt in the Central and Eastern European region and other developing countries. As a result of the fiscal rescue packages, the financing requirement of both developed and emerging countries has increased significantly since 2007, giving rise to substantial changes in risk appetite as well as considerable shifts in demand for the securities of various issuers operating in the global bond markets. During the most severe period of the crisis, only countries with the best credit ratings were able to obtain substantial amounts of funds, while less developed or emerging economies had limited options. In particular, shrinking borrowing opportunities translated into rising yields, weak auction demand and hence unsuccessful auctions. While the market turmoil did not spare less developed euro area countries either; these developments had a particularly negative impact on the government securities markets in the Central and Eastern European region. Although improving risk appetite prompted a parallel rebound in emerging sovereign bond markets, heightened competition for the shrinking financing resources raised the cost of funds in higher-risk economies considerably. Our findings show that – besides developments in risk appetite – demand for the sovereign bonds of emerging countries was also influenced by the crowding-out effect generated by the increased issuance of government papers in developed markets.sovereign debt, risk premium, debt issuance.

Macroeconomic announcements, communication and order flow on the Hungarian foreign exchange market

We investigate the relation between the intradaily HUF/EUR exchange rate on the one hand and news announcements and order flow on the other hand. We extend the existing literature on foreign exchange market microstructure by considering a small open transition economy. We find that the intradaily exchange rate depends on both news announcements and order flow. We conclude that news on the HUF/EUR market are transmitted directly via immediate reactions to news announcements as well as indirectly via order flow. We decompose the news’ total effect on exchange rate and find that order flow accounts for approximately three quarters, compared to one quarter for direct news impact. Although the HUF is pegged to the EUR, the exchange rate reacts very qualitatively very similarly to exchange rates of major currencies as reported in the literature, whereas it quantiatively differs: the importance of indeirect news transmission is remarkably higher on the HUF/EUR market. Furthermore, we extend the commonly used news to communication of central bankers significantly improving the explanatory power of the estimates. Central bank communication is an important determinant for the HUF/EUR rate

A brief overview of the characteristics of interbank forint/euro trading

This study offers some insight into indirect interbank forint/euro trading through transaction-level data from the dominant electronic trading platform used on this market. We provide an in-depth view of the structure and liquidity of interbank foreign exchange trading by using simple, descriptive statistics. Where feasible, the results are placed into an international context. According to our findings, the key structural attributes of the Hungarian foreign exchange market are similar to those of the more advanced markets, despite the significantly lower level of trading volume and other indicators of market liquidity. Trading intensity and liquidity show large variations, both intra-day and between days. Our statistics suggest that the market has become more advanced, more liquid and has grown deeper during the period under review.Exchange rate, foreign exchange market, liquidity.

Regulation of network industries in the European Union and in Central and Eastern Europe

Cost-based pricing has dominated the regulatory regime of network industries - and first of all, the regulation of the infocommunications sector - in the European Union since the early 1990s. When privatization of network industries began in Central and Eastern Europe (CEE), one of the main stumbling blocks on the road toward privately owned telecomm companies and postal services, energy producers and distributors, and other network industries was the lack of efficient and up-to-date industry regulations. From the mid-1990s, accessing countries that later became members of the EU, and other CEE countries that are still waiting for admission swiftly adopted the regulatory framework of the European Union. The EU has been striving for market opening and liberalization in these industries; it abolished industry regulation in several segments of the market of network industries. Now it applies so-called cost-based pricing in areas where regulation is still in place. CEE countries now use the same type of regulation as the advanced member states of the EU. But the regulatory capacity of most CEE countries is still far behind of their West European counterparts. Experts of network industries advocate, and telecommunications, energy and other market regulators in various parts of the world practice, cost-based pricing for inter-firm network access services. Cost-based pricing is carried out under the assumption that the regulator has perfect information regarding the costs of producing the services. We show in this paper that - under fairly general conditions - cost-based pricing creates incentives for regulated firms not to improve their efficiency. We also show that cost-based pricing results in smaller consumer welfare than incentive regulation that takes into account the existence of information asymmetry between the regulator and the firm. A model of interconnection with adverse selection and moral hazard is presented. --network industries,regulation,incentive contracts

Pushing the limits: K2 observations of the trans-Neptunian objects 2002 GV31 and (278361) 2007 JJ43

We present the first photometric observations of trans-Neptunian objects (TNOs) taken with the Kepler space telescope, obtained in the course of the K2 ecliptic survey. Two faint objects have been monitored in specifically designed pixel masks that were centered on the stationary points of the objects, when their daily motion was the slowest. In the design of the experiment, only the apparent path of these objects were retrieved from the detectors, i.e. the costs in terms of Kepler pixels were minimized. Because of the faintness of the targets we employ specific reduction techniques and co-added images. We measure rotational periods and amplitudes in the unfiltered Kepler band as follows: for (278361) 2007 JJ43 and 2002 GV31 we get P_rot=12.097 h and P_rot=29.2 h while 0.10 and 0.35 mag for the total amplitudes, respectively. Future space missions, like TESS and PLATO are not well suited to this kind of observations. Therefore, we encourage to include the brightest TNOs around their stationary points in each observing campaign to exploit this unique capability of the K2 Mission -- and therefore to provide unbiased rotational, shape and albedo characteristics of many objects.Comment: Accepted for publication in ApJ Letters, 5.2 pages in emulateapj style, misspelled 2007 JJ43 designation correcte

Mass and orbit constraints of the gamma-ray binary LS 5039

We present the results of space-based photometric and ground-based spectroscopic observing campaigns on the gamma-ray binary LS 5039. The new orbital and physical parameters of the system are similar to former results, except we found a lower eccentricity. Our MOST-data show that any broad-band optical photometric variability at the orbital period is below the 2 mmag level. Light curve simulations support the lower value of eccentricity and imply that the mass of the compact object is higher than 1.8 solar masses.Comment: 2 pages, 1 figure (with 2 panels); to be published in the Proceedings: From Interacting Binaries to Exoplanets: Essential Modeling Tools, IAU Symposium 282 (18-22 July, 2011, Tatranska Lomnica, Slovakia

Comment on ''Properties of highly clustered networks"

We consider a procedure for generating clustered networks previously reported by Newman [Phys. Rev. E 68, 026121 (2003)]. In the same study, clustered networks generated according to the proposed model have been reported to have a lower epidemic threshold under susceptible-infective-recovered-type network epidemic dynamics. By rewiring networks generated by this model, such that the degree distribution is conserved, we show that the lower epidemic threshold can be closely reproduced by rewired networks with close to zero clustering. The reported lower epidemic threshold can be explained by different degree distributions observed in the networks corresponding to different levels of clustering. Clustering results in networks with high levels of heterogeneity in node degree, a higher proportion of nodes with zero connectivity, and links concentrated within highly interconnected components of small size. Hence, networks generated by this model differ in both clustering and degree distribution, and the lower epidemic threshold is not explained by clustering alone