Gliese 841A - an EUV-selected chromospherically active binary system

We report the discovery of a new short-period, main-sequence, chromospherically active late-type binary system. EUV observations performed by the ROSAT Wide Field Camera have identified the late-type star GL 841A as a possible very active star by virtue of a large EUV-to-bolometric flux ratio. Subsequent optical observations at the wavelengths of the Hα and Ca II H and K lines have confirmed this, and also the binary nature of the system. An orbital period of 1.124 d, an inclination of 28° and a mass ratio of approximately unity are deduced from radial velocity data. Both components show Hα in emission. The photometric colours and absolute magnitude indicate that the component stars are both spectral class dM3-5e. A flare is observed in the Hα emission profile and is attributed to flares on at least one and possibly both the component stars within the space of a few hours. The GL 841A system is similar in many respects to the young eclipsing binary YY Gem but, because GL 841B (the common proper motion, visual binary companion) is a cool dQ7 white dwarf, an age of at least 2 ×109 yr is deduced

RE 1816+541: a northern hemisphere analogue to the low-mass rapid rotator HK Aqr.

Spectroscopic observations of the optical counterpart to the ROSAT Wide Field Camera source RE 1816 + 541 are presented. We find that the counterpart is a chromospherically active, rapidly rotating, dM1-2e star with a sin of 61 km s−1. No evidence for radial velocity variations is found, and we conclude that RE 1816 + 541 is an example of the rare class of single, rapidly rotating field stars, and that it is similar to the southern hemisphere object HK Aqr. Assuming a mainsequence radius, a rotation period of 12 sin hours is predicted. In common with several other active, rapid rotators, RE 1816 + 541 has a radial velocity consistent with membership of the Local Association, a comoving group of young B stars and open clusters such as the Pleiades. On the basis of this and its rapid rotation, we suspect a similar youthful evolutionary status for RE 1816 + 541, making it a good candidate for studying angular momentum loss and extreme magnetic activity in young, low-mass stars

2P-4D AND 2P-4S TRANSITION ARRAYS IN FLUORINE-LIKE COPPER-XXI TO ARSENIC-XXV SPECTRA

The present paper is devoted to the concept of reciprocity and to reciprocal expressions, which are divided into two main classes. Those belonging to the first of them signify reciprocity on their own, i.e. without any additional reciprocal markers. The other class contains expressions that acquire ability to refer to reciprocal states of affairs only as a result of appropriate transformations. Different reciprocal markers – grammatical, lexical and quantifying – are singled out and thoroughly characterized. Their use results in converting non-reciprocal signs into reciprocal ones. They are applied according to the part of speech of a modified term. The conclusion to be drawn from this analysis revolves around the discrepancy between morphological and syntactic means of reciprocal transformation. While the former ones are rather scanty, the latter are largely used in contemporary French.The present paper is devoted to the concept of reciprocity and to reciprocal expressions, which are divided into two main classes. Those belonging to the first of them signify reciprocity on their own, i.e. without any additional reciprocal markers. The other class contains expressions that acquire ability to refer to reciprocal states of affairs only as a result of appropriate transformations. Different reciprocal markers – grammatical, lexical and quantifying – are singled out and thoroughly characterized. Their use results in converting non-reciprocal signs into reciprocal ones. They are applied according to the part of speech of a modified term. The conclusion to be drawn from this analysis revolves around the discrepancy between morphological and syntactic means of reciprocal transformation. While the former ones are rather scanty, the latter are largely used in contemporary French

A quantification of the hazards of fitting sums of exponentials to noisy data

SIGLELD:8053.4155(RL--83-064) / BLDSC - British Library Document Supply CentreGBUnited Kingdo

The abundance of interstellar chlorine in the galaxy

SIGLELD:8053.4155(RAL--84-004) / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Detailed observations of NGC 4151 with IUE Paper 1: low dispersion data up to 1979 January

SIGLELD:1769.7F(RL--81-005)(microfiche). / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Detailed observations of NGC 4151 with IUE Paper 2: variability of the continuum from 1978 February to 1980 May, including x-ray and optical observations

SIGLELD:8053.465(RL--82-013). / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Ultraviolet, optical and infra-red observations of the wolf-rayet contact-eclipsing binary CQ cephei

SIGLELD:8053.4155(RAL--84-005) / BLDSC - British Library Document Supply CentreGBUnited Kingdo