First results of an Hα based search of classical Be stars in the Perseus Arm and beyond

We investigate a region of the Galactic plane, between 120° ≤ l ≤ 140° and-1° ≤ b≤+4°, and uncover a population of moderately reddened (E(B-V) ~ 1) classical Be stars within and beyond the Perseus and Outer Arms. 370 candidate emission-line stars (13≲r≲16) selected from the Isaac Newton Telescope Photometric Ha Survey of the Northern Galactic plane have been followed up spectroscopically. A subset of these, 67 stars with properties consistent with those of classical Be stars, have been observed at sufficient spectral resolution (δλ ≈ 2-4 Å) at blue wavelengths to narrow down their spectral types. We determine these to a precision estimated to be ±1 subtype and then we measure reddenings via spectral energy distribution fitting with reference to appropriate model atmospheres. Corrections for contribution to colour excess from circumstellar discs are made using an established scaling to Ha emission equivalent width. Spectroscopic parallaxes are obtained after luminosity class has been constrained via estimates of distances to neighbouring A/F stars with similar reddenings. Overwhelmingly, the stars in the sample are confirmed as luminous classical Be stars at heliocentric distances ranging from 2 kpc up to ~12 kpc. However, the errors are presently too large to enable the cumulative distribution function with respect to distance to distinguish between models placing the stars exclusively in spiral arms, or in a smooth exponentially declining distribution.Peer reviewe

The second data release of the INT Photometric Ha Survey of the Northern Galactic Plane (IPHAS DR2)

The INT/WFC Photometric Hα Survey of the Northern Galactic Plane (IPHAS) is a 1800 deg2 imaging survey covering Galactic latitudes |b| < 5° and longitudes ℓ = 30°–215° in the r, i, and Hα filters using the Wide Field Camera (WFC) on the 2.5-m Isaac Newton Telescope (INT) in La Palma. We present the first quality-controlled and globally calibrated source catalogue derived from the survey, providing single-epoch photometry for 219 million unique sources across 92 per cent of the footprint. The observations were carried out between 2003 and 2012 at a median seeing of 1.1 arcsec (sampled at 0.33 arcsec pixel−1) and to a mean 5σ depth of 21.2 (r), 20.0 (i), and 20.3 (Hα) in the Vega magnitude system. We explain the data reduction and quality control procedures, describe and test the global re-calibration, and detail the construction of the new catalogue. We show that the new calibration is accurate to 0.03 mag (root mean square) and recommend a series of quality criteria to select accurate data from the catalogue. Finally, we demonstrate the ability of the catalogue's unique (r − Hα, r − i) diagram to (i) characterize stellar populations and extinction regimes towards different Galactic sightlines and (ii) select and quantify Hα emission-line objects. IPHAS is the first survey to offer comprehensive CCD photometry of point sources across the Galactic plane at visible wavelengths, providing the much-needed counterpart to recent infrared surveys

A search for white dwarfs in the Galactic plane: : the field and the open cluster population

This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society. The Version of Record [R. Raddi, et al, ‘A search for white dwarfs in the Galactic plane: the field and the open cluster population’, Monthly Notices of the Royal Astronomical Society, Vol. 457 (2): 1988-2004, first published online 5 February 2016] is available online at doi: https://doi.org/10.1093/mnras/stw042. © 2016 The Author(s). Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.We investigated the prospects for systematic searches of white dwarfs at low Galactic latitudes, using the VLT Survey Telescope (VST) H$\alpha$ Photometric Survey of the Galactic plane and Bulge (VPHAS+). We targeted 17 white dwarf candidates along sightlines of known open clusters, aiming to identify potential cluster members. We confirmed all the 17 white dwarf candidates from blue/optical spectroscopy, and we suggest five of them to be likely cluster members. We estimated progenitor ages and masses for the candidate cluster members, and compared our findings to those for other cluster white dwarfs. A white dwarf in NGC 3532 is the most massive known cluster member (1.13 M$_{\odot}$), likely with an oxygen-neon core, for which we estimate an $8.8_{-4.3}^{+1.2}$ M$_{\odot}$ progenitor, close to the mass-divide between white dwarf and neutron star progenitors. A cluster member in Ruprecht 131 is a magnetic white dwarf, whose progenitor mass exceeded 2-3 M$_{\odot}$. We stress that wider searches, and improved cluster distances and ages derived from data of the ESA Gaia mission, will advance the understanding of the mass-loss processes for low- to intermediate-mass stars.Peer reviewedFinal Published versio

A small-N cross-sectional study of British unions' environmental attitudes and activism - and the prospect of a green-led renewal

Unions understand the environmental agenda as a technocentric one but also believe it can function as a vehicle for renewal. It is developing slowly, with unions behaving cautiously—resources are scarce. Although popular with members, there is limited evidence that it is effective as a recruitment tool and whilst employers are willing to work in partnership with unions on it, this may confer only phony insider status. Overall, the agenda has limited appeal to the types of employees and employers unions must recruit in order to grow. Identifying a clear environmental premium for members may help

Fish oil, melatonin and vitamin e attenuates midbrain cyclooxygenase-2 activity and oxidative stress after the administration of 1-methyl-4-phenyl-1,2, 3,6- tetrahydropyridine

We investigate a region of the Galactic plane, between 120 ? l ? 140 and-1 ? b?+4 , and uncover a population of moderately reddened (E(B-V) ~ 1) classical Be stars within and beyond the Perseus and Outer Arms. 370 candidate emission-line stars (13?r?16) selected from the Isaac Newton Telescope Photometric Ha Survey of the Northern Galactic plane have been followed up spectroscopically. A subset of these, 67 stars with properties consistent with those of classical Be stars, have been observed at sufficient spectral resolution (?? ? 2-4 ) at blue wavelengths to narrow down their spectral types. We determine these to a precision estimated to be 1 subtype and then we measure reddenings via spectral energy distribution fitting with reference to appropriate model atmospheres. Corrections for contribution to colour excess from circumstellar discs are made using an established scaling to Ha emission equivalent width. Spectroscopic parallaxes are obtained after luminosity class has been constrained via estimates of distances to neighbouring A/F stars with similar reddenings. Overwhelmingly, the stars in the sample are confirmed as luminous classical Be stars at heliocentric distances ranging from 2 kpc up to ~12 kpc. However, the errors are presently too large to enable the cumulative distribution function with respect to distance to distinguish between models placing the stars exclusively in spiral arms, or in a smooth exponentially declining distribution. " 2013 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society.",,,,,,"10.1093/mnras/stt038",,,"http://hdl.handle.net/20.500.12104/41535","http://www.scopus.com/inward/record.url?eid=2-s2.0-84876811129&partnerID=40&md5=7c537a0a3a76c0f1bd980e198a951b74",,,,,,"3",,"Monthly Notices of the Royal Astronomical Society",,"216

White dwarfs in Galactic plane

Item does not contain fulltextHere, we use the primary detections of the VPHAS+ data release 2 (DR2) (Drew et al., 2014, Cat. II/341), accessible through the ESO Science Archive. It delivers PSF magnitudes, expressed in the Vega system, for 24 per cent of the survey area. We acquired optical spectroscopy for 17 white dwarf candidates on 2014 April 28-30 with the visual and near-UV FOcal Reducer and low dispersion Spectrograph (FORS2), mounted on the Very Large Telescope (VLT) UT1 (Antu)