Recent Submissions

  • Near-Infrared [Fe II] and H<SUB>2</SUB> Study of the Galactic Supernova Remnants

    Seoul National University; Korea Astronomy and Space Science Institute; University of Texas at Austin; Armagh Observatory and Planetarium; Australian Astronomical Observatory; Lee, Yong-Hyun; Koo, Bon-Chul; Lee, Jae-Joon; Jaffe, Daniel T.; Burton, Michael G.; et al. (American Astronomical Society Meeting Abstracts #231, 2018-01-01)
    We have searched for near-infrared (NIR) [Fe II] (1.644 μm) and H<SUB>2</SUB> 1-0 S(1) (2.122 μm) emission features associated with Galactic supernova remnants (SNRs) using the narrow-band imaging surveys UWIFE / UWISH2 (UKIRT Widefield Infrared Survey for [Fe II] / H<SUB>2</SUB>). Both surveys cover about 180 square degrees of the first Galactic quadrant (7° &lt; l &lt; 65° -1.3° &lt; b &lt; +1.3°), and a total of 79 SNRs are falling in the survey area. We have found 19 [Fe II]- and 19 H<SUB>2</SUB>-emitting SNRs, giving a detection rate of 24%. Eleven SNRs show both emission features. Some of the SNRs show bright, complex, and interesting structures that have never been reported in previous studies. The brightest SNR in the both emission is W49B, contributing ~70% of the total [Fe II] luminosity of the detected SNRs. The total [Fe II] luminosity, however, is considerably less than what we would expect from the SN rate of our Galaxy.Among the SNRs showing both [Fe II] and H<SUB>2</SUB> emission lines, some SNRs show the “[Fe II]-H<SUB>2</SUB> reversal” phenomenon, i.e., the H<SUB>2</SUB> emission features are detected outside the [Fe II] emission boundary. We carried out high resolution (R~40,000) NIR H- and K-band spectroscopy of the five SNRs showing the [Fe II]-H<SUB>2</SUB> reversal (G11.2-0.3, KES 73, W44, 3C 396, W49B) using IGRINS (Immersion GRating INfrared Spectrograph). Various ro-vibrational H<SUB>2</SUB> lines have been detected, which are used to derive the kinematic distances to the SNRs and to investigate the origin of the H<SUB>2</SUB> emission. The detected H<SUB>2</SUB> lines show broad line width (&gt; 10 km s<SUP>-1</SUP>) and line flux ratios of thermal excitation. We discuss the origin of the extended H<SUB>2</SUB> emission features beyond the the [Fe II] emission boundary.
  • Highly Excited Molecular Hydogren in Shocked Molecular Gas: Line Emission from Newly Reformed H<SUB>2</SUB>?

    Gemini Obs; Armagh Observatory; Academia Sinica; Geballe, Thomas R.; Burton, Michael G.; Pike, Rosemary E. (American Astronomical Society Meeting Abstracts #230, 2017-06-01)
    We report high sensitivity K-band spectra of the Herbig-Haro 7 bow shock and selected portions of the energetic outflow in the Orion Molecular Cloud, each a location of bright line emission by shocked molecular hydrogen (H<SUB>2</SUB>). Among the many detected emission lines of H<SUB>2</SUB> are some from highly excited ro-vibrational levels, with upper state energies as high as the dissociation limit near 50,000 K, much higher than previously observed. In all cases the H<SUB>2</SUB> level populations are well fit by a two-temperature model with the vast majority of the H<SUB>2</SUB> at a temperature near 2,000 K but with one to a few percent of the H<SUB>2</SUB> at a temperature near 5,000 K. The existence of the latter H<SUB>2</SUB> appears to be broadly consistent with it having recently reformed following collisional dissociation by the shock; however, the well-defined kinetic temperature of 5,000 K is surprising. The presence of such high temperature H<SUB>2</SUB> appears to be a common characteristic of shock-excited molecular gas.
  • Infrared Line Emission in the Herbig-Haro 7 Bowshock from 5,000 K Molecular Hydrogen in Quasi-bound States

    Gemini Observatory / NSF's NOIRLab; Armagh Observatory and Planetarium; Observatoire de Paris; Geballe, Thomas; Burton, Michael; Roueff, Evelyne; Abgrall, Herve (American Astronomical Society Meeting Abstracts, 2023-01-01)
    Previous spectroscopy of shock-excited H2 line emission in the Herbig-Haro 7 (HH7) bow shock and in the Orion Molecular Cloud (OMC-1) outflow has demonstrated that, although the vast majority of the line emission in those regions comes from gas at T ≈ 2,000 K, as expected for continuous shocks, 1-2% of the H2 is in LTE at a temperature of ~5,000 K. The existence of this latter component of the H2 is not explained by current shock models. One H2 line detected in HH7 is emitted from the quasi-bound v=2 J=29 level, whose energy is ~700 K above the dissociation limit of the ground state of H2. New calculations of the properties of quasi-bound H2 levels have led to the identification of a previously unidentified line in the HH7 spectrum as originating in a second quasi-bound state, v=1, J=31, ~1500 K above the dissociation limit. The existence of this 5,000 K gas and the confirmation that shock-excited H2 in molecular clouds exists in the above highly excited states offer new opportunities to study and more fully understand shock-excitation in molecular clouds.
  • ISM studies towards several PWNe

    School of Physical Sciences, University of Adelaide 5005, Australia;; School of Physical Sciences, University of Adelaide 5005, Australia; School of Physics, University of New South Wales, Sydney, NSW 2052, Australia; Armagh Observatory and Planetarium, College Hill, Armagh BT 61 9DG, Northern Ireland; Department of Physics, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8601, Japan; Dublin Institute for Advanced Studies, Dublin 2, Ireland; Max-Planck-Institut für Kernphysik, Heidelberg, Germany; Voisin, F.; Rowell, G.; Burton, M. G.; Fukui, Y.; Sano, H.; et al. (6th International Symposium on High Energy Gamma-Ray Astronomy, 2017-01-01)
    Pulsar wind Nebulae (PWNe) represent the largest population of TeV sources detected by H.E.S.S. Here, we present a ISM study combining 7mm Mopra observations with Nanten CO(1-0) and SGPS Hi data to understand the ISM environment towards HESS J1809-193, HESS J1026-582 and HESS J1826-130, as well as the morphology of the TeV source gamma-ray emission. Combining the TeV emission with several extended dense regions will then be useful to quantify the distinguish the contribution from PWNe and SNRs towards various HESS TeV sources.
  • The Of?p Stars of the Magellanic Clouds: Are They Strongly Magnetic?

    Queen's University, 99 University Ave, Kingston, Ontario, Canada, 16msm5@queensu.ca; Royal Military College of Canada, 13 General Crerar Crescent, Kingston, Ontario, Canada; Université de Liège, Place du 20 Aoû t 7, 4000 Liège, Belgium; Armagh Observatory, College Hill, Armagh BT61 9DG, Northern Ireland, United Kingdom; Universitätssternwarte, Scheinerstr. 1, D-81679 München, Germany; Munoz, Melissa; Wade, Gregg A.; Nazé, Yaël; Bagnulo, Stefano; Puls, Joachim (3rd BRITE Science Conference, 2018-08-01)
    All known Galactic Of?p stars have been shown to host strong, organized, magnetic fields. Recently, five Of?p stars have been discovered in the Magellanic Clouds. They posses photometric tep{Naze} and spectroscopic tep{Walborn} variability compatible with the Oblique Rotator Model (ORM). However, their magnetic fields have yet to be directly detected. We have developed an algorithm allowing for the synthesis of photometric observables based on the Analytic Dynamical Magnetosphere (ADM) model of tet{Owocki}. We apply our model to OGLE photometry in order to constrain their magnetic geometries and surface dipole strengths. We predict that the field strengths for some of these candidate extra-Galactic magnetic stars may be within the detection limits of the FORS2 instrument.
  • Fifty Years of Observations of Grw+70(°) 8247

    Armagh Observatory &amp; Planetarium, College Hill, Armagh BT61 9DG, UK; Bagnulo, S. (Stellar Magnetism: A Workshop in Honour of the Career and Contributions of John D. Landstreet, 2020-11-01)
    Among white dwarfs, Grw+70$^\circ$ 8247 stands as a particularly interesting object for various reasons. It is the first white dwarf in which a magnetic field was discovered. It is one of the stars with the longest rotation period (probably between 100 and 1000 yr). It shows one of the most unusual optical spectra ever seen because spectral lines are produced in presence of one of the strongest magnetic fields ever measured in the universe ($\sim 400$ MG). Most importantly, this star has been the subject of a number of scientific articles co-authored by John Landstreet, from the one reporting the discovery of its magnetic field in 1970, to a very recent paper which presents new spectropolarimetric observations obtained from the William Herschel Telescope. Here I will show how the polarisation spectra of the star have changed during John's career, and what we have learnt from the observations of this star.
  • Thomas Richard (Dick) Carson (1930-2019)

    Senior research astronomer at Armagh Observatory and Planetarium, Northern Ireland; Jeffery, Simon (Astronomy and Geophysics, 2020-04-01)
    Simon Jeffery recalls a dedicated colleague whose work made stellar opacities and pulsations central to models of stellar evolution.
  • Armagh Observatory's meridian marks

    Emeritus Research Fellow at Armagh Observatory; Butler, John (Astronomy and Geophysics, 2016-04-01)
    John Butler surveys the extant and vanished meridian marks of Armagh Observatory and explains their significance for 18th and 19th century observations.
  • Starquakes spring stellar surprises

    Jeremiah Horrocks Institute of Astrophysics, University of Central Lancashire, Preston, UK; Armargh Observatory, Armagh, UK; Instituut voor Sterrenkunde, KU Leuven, Belgium; Kurtz, Don; Jeffrey, Simon; Aerts, Conny (Astronomy and Geophysics, 2016-08-01)
    Don Kurtz, Simon Jeffrey and Conny Aerts describe discoveries in the new era of precision asteroseismology.
  • Where past meets future

    Director of the Armagh Observatory and Planetarium; Burton, Michael (Astronomy and Geophysics, 2023-02-01)
    Ireland's historic astronomical observatories at Armagh, Birr and Dunsink are embarking on the process of seeking UNESCO World Heritage Status. Michael Burton examines the deep astronomical heritage that they embody.
  • Erratum: Circular polarimetry of suspect wind-accreting magnetic pre-polars

    Finnish Centre for Astronomy with ESO (FINCA), Quantum, University of Turku, FI-20014, Finland; Department of Physics and Astronomy, University of Sheffield, Sheffield S3 7RH, UK; Department of Physics, University of Warwick, Coventry CV4 7AL, UK; Armagh Observatory and Planetarium, College Hill, Armagh BT61 9DG, UK; Leibniz Institute for Astrophysics Potsdam (AIP), An der Sternwarte 16, D-14482 Potsdam, Germany; Department of Astronomy, Boston University, 725 Commonwealth Ave., Boston, MA 02215, USA; Hakala, Pasi; Parsons, Steven G.; Marsh, Thomas R.; Gänsicke, Boris T.; et al. (Monthly Notices of the Royal Astronomical Society, 2022-10-01)
  • The quest for magnetic massive stars in the Magellanic Clouds

    FNRS/Univ. Liège, Belgium; Armagh Obs., Ireland; STScI, USA; LCO, Chile; RMC, Canada; Warsaw Univ., Poland; Univ. Wisconsin-Madison, USA; Nazé, Y.; Bagnulo, S.; Walborn, N. R.; et al. (The Lives and Death-Throes of Massive Stars, 2017-11-01)
    The Of?p category was introduced more than 40 years ago to gather several Galactic stars with some odd properties. Since 2000, spectropolarimetry, high-resolution spectroscopy, long-term photometry, and X-ray observations have revealed their nature: magnetic oblique rotators - they all have magnetic fields that confine their winds. Several Of?p stars have now been detected in the Magellanic Clouds, likely the prototypes of magnetic massive stars at low metallicity. This contribution will present the most recent photometric, spectroscopic, and spectropolarimetric data, along with the first modeling of these objects.
  • Polarimetric Calibration and Accuracy: Lessons Learnt from Present Instrumentation

    Armagh Observatory and Planetarium, U.K.; Bagnulo, Stefano (ESO Calibration Workshop: The Second Generation VLT Instruments and Friends, 2017-09-01)
    We will discuss several sources of non-photon noise that may prevent the current polarimetric instrumentation from reaching the accuracy needed in various astronomical applications, from the detection of weak magnetic fields to the characterisation of (exo) planetary atmospheres and the search of extra-terrestrial life. Lessons learnt today will help to improve the design of future instrumentation.
  • The MopraCO Galactic Survey

    University of South Wales (Sidney), INAF Roma Tor Vergata; University of South Wales (Sidney), Armagh Observatory and Planetarium (Northern Ireland UK); University of South Wales (Sidney),; INAF Roma Tor Vergata; University of South Wales (Sidney); Romano, Domenico; Burton, Michael; Braiding, Catherine; Molinari, Sergio; Ashley, Michael (Workshop sull'Astronomia Millimetrica in Italia, 2017-11-01)
    The MopraCO project (see also Burton et al., 2013, Braiding et al., 2015, Rebolledo et al., 2016) is a CO J=1-0 line survey across the 4th Quadrant of the Milky Way, performed using the 22 m diameter single dish Mopra telescope in Australia. It includes the three main CO molecule isotopologues (12CO , 13CO and C18O) and more than 100 square degrees have been surveyed, spanning from l=265deg to +10deg and b= ± 0.5deg, covering also the Carina complex and the Central Molecular Zone, and extending beyond b= ± 0.5o in several regions. The final plan is to cover from l=265deg to +10deg and b= ± 1deg. The use of the 8 GHz-wide UNSW-MOPS spectrometer and the fast mode of on-the-fly mapping, developed for the Mopra telescope, permits us to reduce the cycle time to 1/4 of a second. <P />Compared with the previous Dame et al. 2001 CO survey of the Southern Galactic plane the MopraCO spectral and angular resolution of 0.1 km/s and 0.6' are an order of magnitude better. This permits us to improve the model of our Galaxy, showing the spirals structures with unprecedented details, in particular in the inner regions where the tracers of spiral arm tangents show an offset from the mid-arms that is matched by maser data, while the real structure of the innermost region remains difficult to define. Furthermore, the 12CO/13CO line ratios are found to be higher in the diffuse gas outside the GMC complexes than inside them, opening new hypothesis on the Xco factor used to estimate the masses of the molecular clouds. <P />Providing a detailed large scale third dimension, across the Southern Galaxy in the wide range of velocity (-500 to 450 km/s), the combination of this survey with the other ones will help to investigate the dark gas fraction not traced by the CO, better characterise the evolution of the molecular clouds and of the dense core inside them, giving more insights on the early stages of massive star formation. <P />In particular, in the direction toward the galactic longitude 332 at a distance of ∼ 3.5 kpc, we discovered a new giant molecular ring, around 40 pc in diameter, which presents strong emissions in the 12O and in 13CO lines as well as in atomic carbon and other tracers.
  • Serving two masters: Triton as an immigrant planetary moon

    Lund Observatory, Department of Astronomy and Theoretical Physics, Lund University, Lund, Sweden; Armagh Observatory and Planetarium, Armagh, UK; Li, Daohai; Johansen, Anders; Mustill, Alexander; Davies, Melvyn; Christou, Apostolos (EPSC-DPS Joint Meeting 2019, 2019-09-01)
    Triton is the largest Neptunian moon. At only a few tens of planetary radii, this moon is actually moving backwards as viewed from its host, inconsistent with how we think satellites form around their planets. Here we show that if formed around another planet, Triton can be captured by Neptune when the two planets encounter each other in the early solar system.
  • Chaotic transport of Main Belt asteroids in Martian resonances

    Armagh Observatory, Armagh, United Kingdom; University of Florida, Gainesville, USA; University of Pennsylvania, Philadelphia, USA; Christou, Apostolos; Dermott, Stanley; Li, Dan (European Planetary Science Congress, 2018-09-01)
    We investigate chaotic orbit mobilisation in the Inner Main Belt by Martian resonances, a potential delivery mechanism of asteroids and meteorites to planet-crossing orbits. We find that, while there is little change in the orbit outside the resonances, asteroids in the resonances undergo significant chaotic evolution. We conclude that local dynamics play an important role in mobilising bodies that eventually become NEAs and meteorites.
  • Testing the Yarkovsky-driven evolution of the Eureka cluster with LSST

    Armagh Observatory and Planetarium, College Hill, Armagh BT61 9DG, UK; Christou, Apostolos A. (IAU General Assembly, 2020-03-01)
  • Obituary: Thomas Richard (Dick) Carson (1930-2019)

    Armagh Observatory; University of Oxford; University of St. Andrews; Jeffery, Simon; Lynas-Gray, Tony; Hilditch, Ron (Bulletin of the American Astronomical Society, 2020-12-01)
    Carson wrote foundational papers in the field of stellar opacity, which he later applied to calculations of stellar structure and pulsation. He spent the bulk of his career at the University of St. Andrews.
  • Change in General Relativistic precession rates due to Lidov-Kozai oscillations in the Solar System

    CEED, University of Oslo, Centre for Earth Evolution and Dynamics, Oslo, Norway; Armagh Observatory and Planetarium, Armagh BT61 9DG, United Kingdom; IMCCE, Observatoire de Paris, 77 Avenue Denfert Rochereau, F-75014 Paris, France; Harvard-Smithsonian Center for Astrophysics, Cambridge, MA, USA; Sekhar, Aswin; Asher, David J.; Werner, Stephanie C.; Vaubaillon, Jeremie; Li, Gongjie (EGU General Assembly Conference Abstracts, 2017-04-01)
    Introduction: Two well known phenomena associated with low perihelion distance bodies in orbital dynamics are general relativistic (GR) precession and Lidov-Kozai (LK) oscillations. The accurate prediction of the perihelion shift of Mercury in accord with real observations is one of the significant triumphs of the general theory of relativity developed by Einstein. The Lidov-Kozai mechanism was first proposed and derived by Kozai and independently by Lidov explaining the periodic exchange between eccentricities e and inclinations i thereby increasing or decreasing the perihelion distance q secularly in the orbiting body. Co-existence of GR Precession and LK Oscillations: In this work, we were interested to identify bodies evolving in the near future (i.e. thousands of years in this case) into rapid sungrazing and sun colliding phases and undergoing inclination flips, due to LK oscillations and being GR active at the same time. Of all the bodies we checked from the IAU-Minor Planet Center, and Marsden plus Kracht families from the comet catalogue, 96P/Machholz 1 stands out because it shows all these trends in the near future. LK leads to secular lowering of q which in turn leads to a huge increase in GR precession of argument of pericentre. This in turn gives feedback to the LK mechanism as the e,i and argument of pericentre in Kozai cycles are closely correlated. In this work, we find real examples of solar system bodies which show the continuum nature between GR precession domi-nant and LK mechanism dominant regimes. Results and Discussion: We have shown that there are bodies in the solar system in which both GR precession and LK mechanism can co-exist at the same time and for which these effects can be measured and identified using analytical and numerical techniques. Thus there is a continuum of bodies encompassing, firstly GR precession dominant, secondly GR precession plus LK mechanism co-existing and finally LK mechanism dominant states which are all permissible in nature. A real solar system body in this intermediate state is identified using compiled observational records from IAU-Minor Planet Center, Cometary Catalogue, IAU-Meteor Data Center and performing analytical plus numerical tests on them. This intermediate state brings up the interesting possibility of drastic changes in GR precession rates (at some points peaking to about 60 times that of Mercury's GR precession) during orbital evolution due to sungrazing and sun colliding phases induced by the LK mechanism, thus combining both these important effects in a unique and dynamically interesting way. Comet 96P/Machholz 1 stands out as the only real body identified (from our simulations) to be exhibiting these interesting traits, as well as inclination flips, in the near future. Both these phenomena complimenting and co-existing at the same time has interesting implications in the long term impact studies of small bodies in general.
  • VST: The First Large Survey Telescope for Optical Polarimetry

    ESO; Armagh Observatory; -; Smette, Alain; Bagnulo, Stefano; Snik, Frans; Cox, Nick; Hainaut, Olivier; Hutsemekers, Damien; Magalhaes, Antonio Mario (VST in the Era of the Large Sky Surveys, 2018-06-01)
    Replacing the unused ADC by a polarizing filter would transform the VST into the first large polarimetric optical survey telescope, without affecting the current capabilities of the VST+OmegaCAM system. <P />Scientific cases include: mapping the Milky-Way and Magellanic clouds magnetic fields, surveys of quasar polarization, identification and variability of polarized brown dwarfs, polarimetric characterization and mapping of solar-system objects (incl. the moon, comets, and asteroids), detection of polarized signal around the L4 and L5 Lagrange points, a census of magnetic white dwarfs and Herbig Ae/Be stars, etc. <P />The design of the VST limits the technical implementation for the polarimetric unit to a single-beam system: therefore, we will develop data-driven calibration methods to achieve a sub-percent polarimetric accuracy. <P />The proposed implementation is of low cost and requires no major development, as polarizing filters of the needed size are readily available. In particular, it does not require major modification neither of VST, nor of OmegaCAM. In fact, the currently offered capabilities of the VST+OmegaCAM are preserved as the polarizing filter can be removed from the optical beam. Would this project be accepted, efforts will be needed on the design of the polarimeter unit to optimize accuracy and execution times, on the design of the calibration plan, and on the extension of the data reduction pipeline to extract the polarization signals.

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