Jets from young stars and brown dwarfs

The protostellar outflow mechanism operates for a significant fraction of the pre-main sequence phase of a solar mass star and is thought to have a key role in star and perhaps even planet formation. This energetic mechanism manifests itself in several different forms and on many scales. Thus outflow activity can be probed in numerous different regimes from radio to X-ray wavelengths. Recent discoveries have shown that it is not only solar mass stars that launch outflows during their formation but also the sub-stellar brown dwarfs. In this article what is currently known about jets from young stars is summarised, including an outline of why it is important to study jets. The second part of this article is dedicated to jets from young brown dwarfs. While only a small number of brown dwarf outflows have been investigated to date, interesting properties have been observed. Here observations of brown dwarf outflows are described and what is currently known of their properties compared to low mass protostellar outflows.Comment: Astronomische Nachrichten, Special Issue: Reviews in Modern Astrononm

From Income Poverty to Quality of Life Measurement in Ireland, an Overview 1. ESRI Research Bulletin February 2020/03

There is an increasing consensus that the identification and measurement of poverty using a single income measure fails to capture the complexity of poverty. This was particularly true in Ireland in periods of bust and boom, when relative income poverty measures were unable to reflect the changes in standard of living. Such limits highlight the need to develop a multidimensional approach. This requires developing criteria relating to choice of dimensions and the manner in which they should be combined

Social Mobility in Ireland in the 1990s - Evidence from the 1994 Living in Ireland Survey

In this paper we seek to update findings relating to class mobility outcomes and processes in the Republic of Ireland employing data from the Living in Ireland Survey which was carried out in 1994. We also provide an evaluation of a measured variable model of the mobility process developed on an earlier data set. Our findings confirm that transformation of the class structure has been associated with substantial levels of social mobility. At the same time inequalities of opportunity as reflected in the underlying patterns of social fluidity remain substantial and are constant across cohorts. Gender differences are almost entirely a consequence of occupational segregation and there is no evidence that the underlying processes of class disadvantage operate differently for men and women.

Understanding the Implications of Choice of Deprivation Index for Measuring Consistent Poverty in Ireland

In this paper we make use of the Irish component of the European Union Community Statistics on Income and Living Conditions (EU-SILC) survey for 2004 in order to develop a measure of consistent poverty that overcomes some of the difficulties associated with the original indicators employed as targets in the Irish National Anti-Poverty Strategy. Our analysis leads us to propose a set of basic deprivation items that covers a broader range than the original set and provides a more reliable and valid measure. Consistent poverty measures incorporating the revised basic deprivation measure and adopting a threshold of two or more items provide similar estimates of levels of poverty to the original measure. The new broader measure is more strongly associated with current income, surrogates for permanent income and subjective economic pressures. Furthermore, by constructing a consistent poverty typology we are able to demonstrate that when we contrast those defined as poor when employing the new 11-item index but not the 8-item one with those for whom the opposite is true the former display a multidimensional deprivation profile that is substantially less favourable. The accumulated evidence supports the view that the revised consistent poverty measures, which combine a threshold of two or more items on the broader basic deprivation index comprising the 11-item index available in EU-SILC with income poverty, identify those exposed to generalised deprivation arising from lack of resources. This revised deprivation threshold taken together with being below 60 per cent of median income has now been adopted as the official consistent poverty measure in the Irish National Action Plan for Social Inclusion.

HH 1158: The lowest luminosity externally irradiated Herbig-Haro jet

We have identified a new externally irradiated Herbig-Haro (HH) jet, HH 1158, within ~2 pc of the massive OB type stars in the sigma Orionis cluster. At an Lbol ~ 0.1 Lsun, HH 1158 is the lowest luminosity irradiated HH jet identified to date in any cluster. Results from the analysis of high-resolution optical spectra indicate asymmetries in the brightness, morphology, electron density, velocity, and the mass outflow rates for the blue and red-shifted lobes. We constrain the position angle of the HH 1158 jet at 102+/-5 degree. The mass outflow rate and the mean accretion rate for HH 1158 using multiple diagnostics are estimated to be (5.2 +/- 2.6) x 10^(-10) Msun/yr and (3.0 +/- 1.0) x 10^(-10) Msun/yr, respectively. The properties for HH 1158 are notably similar to the externally irradiated HH 444 -- HH 447 jets previously identified in sigma Orionis. In particular, the morphology is such that the weaker jet beam is tilted towards the massive stars, indicating a higher extent of photo-evaporation. The high value for the Halpha/[SII] ratio is also consistent with the ratios measured in other irradiated jets, including HH 444 -- HH 447. The presence of an extended collimated jet that is bipolar and the evidence of shocked emission knots make HH 1158 the first unique case of irradiated HH jets at the very low-luminosity end, and provides an opportunity to learn the physical properties of very faint HH jet sources.Comment: Accepted in ApJ Letter

Stochastic Gravitational Wave Measurements with Bar Detectors: Dependence of Response on Detector Orientation

The response of a cross-correlation measurement to an isotropic stochastic gravitational-wave background depends on the observing geometry via the overlap reduction function. If one of the detectors being correlated is a resonant bar whose orientation can be changed, the response to stochastic gravitational waves can be modulated. I derive the general form of this modulation as a function of azimuth, both in the zero-frequency limit and at arbitrary frequencies. Comparisons are made between pairs of nearby detectors, such as LIGO Livingston-ALLEGRO, Virgo-AURIGA, Virgo-NAUTILUS, and EXPLORER-AURIGA, with which stochastic cross-correlation measurements are currently being performed, planned, or considered.Comment: 17 pages, REVTeX (uses rcs, amsmath, hyperref, and graphicx style files), 4 figures (8 eps image files