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  • X-Shooting ULLYSES: Massive Stars at Low Metallicity

    Armagh Observatory and Planetarium, UK; Department of Physics & Astronomy, University of Sheffield, UK; Space Telescope Science Institute, Baltimore, USA; Centre for Astrobiology (CSIC-INTA), Torrejón de Ardoz, Madrid, Spain; Montpellier Universe and Particles Laboratory, Montpellier University, France; Las Campanas Observatory, Carnegie Observatories, Chile; Institute for Physics and Astronomy, University of Potsdam, Germany; Department of Physics, University of Montreal, Canada; Penn State Scranton, Dunmore, PA, USA; Astronomy Centre, Heidelberg University, Germany; et al. (The Messenger, 2024-03-01)
    The Hubble Space Telescope has devoted 500 orbits to observing 250 massive stars with low metallicity in the ultraviolet (UV) range within the framework of the ULLYSES program. The X-Shooting ULLYSES (XShootU) project enhances the legacy value of this UV dataset by providing high-quality optical and near-infrared spectra, which are acquired using the wide-wavelength- coverage X-shooter spectrograph at ESO's Very Large Telescope. XShootU emphasises the importance of combining UV with optical spectra for the consistent determination of key stellar parameters such as effective temperature, surface gravity, luminosity, abundances, and wind characteristics including mass-loss rates as a function of metallicity. Since uncertainties in these parameters have implications across various branches of astrophysics, the data and modelling generated by the XShootU project are poised to significantly advance our understanding of massive stars at low metallicity. This is particularly crucial for confidently interpreting James Webb Space Telescope (JWST) data of the earliest stellar generations, making XShootU a unique resource for comprehending individual spectra of low-metallicity stars.
  • A study of galactic plane Planck galactic cold clumps observed by SCOPE and the JCMT plane survey

    Armagh Observatory and Planetarium, College Hill, Armagh, BT61 9DB, UK; Shanghai Astronomical Observatory, Chinese Academy of Sciences, 80 Nandan Road, Shanghai 200030, People's Republic of China; Astrophysics Research Institute, Liverpool John Moores University, Liverpool Science Park, iC2, 146 Brownlow Hill. Liverpool, L3 5RF, UK; NRC Herzberg Astronomy and Astrophysics, 5071 West Saanich Rd, Victoria, BC V9E 2E7, Canada; Department of Physics and Astronomy, University of Victoria, Victoria, BC V8W 2Y2, Canada; Jodrell Bank Centre for Astrophysics, School of Physics and Astronomy, The University of Manchester, Oxford Road, Manchester M13 9PL, UK; Korea Astronomy and Space Science Institute, 776 Daedeokdae-ro, Yuseong-gu, Daejon 34055, Republic of Korea; University of Science and Technology, Korea (UST), 217 Gajeong-ro, Yuseong-gu, Daejeon 34113, Republic of Korea; National Astronomical Observatories, Chinese Academy of Sciences, Beijing, 100012, China; Key Laboratory of Radio Astronomy, Chinese Academy of Science, Nanjing 210008, China; Academia Sinica Institute of Astronomy and Astrophysics, 11F of AS/NTU Astronomy-Mathematics Building, No.1, Section 4, Roosevelt Rd, Taipei 10617, Taiwan; Department of Physics and Astronomy, University of Calgary, 2500 University Drive NW, Calgary, Alberta T2N 1N4, Canada; Nobeyama Radio Observatory, National Astronomical Observatory of Japan, National Institutes of Natural Sciences, Nobeyama, Minamimaki, Minamisaku, Nagano 384-1305, Japan; Astronomical Science Program, Graduate Institute for Advanced Studies, SOKENDAI, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan; et al. (Monthly Notices of the Royal Astronomical Society, 2024-05-01)
    We have investigated the physical properties of Planck Galactic Cold Clumps (PGCCs) located in the Galactic Plane, using the JCMT Plane Survey (JPS) and the SCUBA-2 Continuum Observations of Pre-protostellar Evolution (SCOPE) survey. By utilising a suite of molecular-line surveys, velocities and distances were assigned to the compact sources within the PGCCs, placing them in a Galactic context. The properties of these compact sources show no large-scale variations with Galactic environment. Investigating the star-forming content of the sample, we find that the luminosity-to-mass ratio (L/M) is an order of magnitude lower than in other Galactic studies, indicating that these objects are hosting lower levels of star formation. Finally, by comparing ATLASGAL sources that are associated or are not associated with PGCCs, we find that those associated with PGCCs are typically colder, denser, and have a lower L/M ratio, hinting that PGCCs are a distinct population of Galactic Plane sources.
  • The wide-field, multiplexed, spectroscopic facility WEAVE: Survey design, overview, and simulated implementation

    Oxford Astrophysics, University of Oxford, Keble Road, Oxford OX1 3RH, UK; Kapteyn Astronomical Institute, Rijksuniversiteit Groningen, Landleven 12, 9747 AD Groningen, The Netherlands; RALSpace, STFC, Harwell, Didcot OX11 0QX, UK; SRON - Netherlands Institute for Space Research, Landleven 12, 9747 AD Groningen, The Netherlands; Kapteyn Astronomical Institute, Rijksuniversiteit Groningen, Landleven 12, 9747 AD Groningen, The Netherlands; Oxford Astrophysics, University of Oxford, Keble Road, Oxford OX1 3RH, UK; RALSpace, STFC, Harwell, Didcot OX11 0QX, UK; Instituto de Astrofísica de Canarias, Calle Vía Láctea s/n, 38205 La Laguna, Santa Cruz de Tenerife, Spain; Departamento de Astrofísica, Universidad de La Laguna, 38206 La Laguna, Tenerife, Spain; Centre for Astrophysics Research, University of Hertfordshire, Hatfield, Hertfordshire AL10 9AB, UK; Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, UK; Department of Physics, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, UK; Université Côte d'Azur, Observatoire de la Côte d'Azur, CNRS, Laboratoire Lagrange, Bd de l'Observatoire, CS 34229, 06304 Nice Cedex 4, France; INAF - Osservatorio Astronomico di Brera, Via Brera, 28, 20121 Milano, Italy; Aix Marseille Univ, CNRS, CNES, LAM, Laboratoire d'Astrophysique de Marseille, 13388 Marseille, France; INAF - Osservatorio Astronomico di Padova, Vicolo Osservatorio 5, 35122 Padova, Italy; et al. (Monthly Notices of the Royal Astronomical Society, 2024-05-01)
    WEAVE, the new wide-field, massively multiplexed spectroscopic survey facility for the William Herschel Telescope, saw first light in late 2022. WEAVE comprises a new 2-deg field-of-view prime-focus corrector system, a nearly 1000-multiplex fibre positioner, 20 individually deployable 'mini' integral field units (IFUs), and a single large IFU. These fibre systems feed a dual-beam spectrograph covering the wavelength range 366-959 nm at R ~ 5000, or two shorter ranges at $R\sim 20\, 000$. After summarizing the design and implementation of WEAVE and its data systems, we present the organization, science drivers, and design of a five- to seven-year programme of eight individual surveys to: (i) study our Galaxy's origins by completing Gaia's phase-space information, providing metallicities to its limiting magnitude for ~3 million stars and detailed abundances for ~1.5 million brighter field and open-cluster stars; (ii) survey ~0.4 million Galactic-plane OBA stars, young stellar objects, and nearby gas to understand the evolution of young stars and their environments; (iii) perform an extensive spectral survey of white dwarfs; (iv) survey ~400 neutral-hydrogen-selected galaxies with the IFUs; (v) study properties and kinematics of stellar populations and ionized gas in z < 0.5 cluster galaxies; (vi) survey stellar populations and kinematics in ${\sim} 25\, 000$ field galaxies at 0.3 ≲ z ≲ 0.7; (vii) study the cosmic evolution of accretion and star formation using >1 million spectra of LOFAR-selected radio sources; and (viii) trace structures using intergalactic/circumgalactic gas at z > 2. Finally, we describe the WEAVE Operational Rehearsals using the WEAVE Simulator.
  • The S-PLUS Fornax Project (S+FP): A first 12-band glimpse of the Fornax galaxy cluster

    Instituto de Astrofísica de La Plata, CONICET-UNLP, Paseo del Bosque s/n, B1900FWA, Argentina; Facultad de Ciencias Astronómicas y Geofísicas, Universidad Nacional de La Plata, Paseo del Bosque s/n, B1900FWA, Argentina; Valongo Observatory, Federal University of Rio de Janeiro, Ladeira Pedro Antonio 43, Saude Rio de Janeiro, RJ, 20080-090, Brazil; Instituto de Fisica, Universidade Federal do Rio de Janeiro, 21941-972, Rio de Janeiro, RJ, Brazil; Instituto de Astrofísica de La Plata, CONICET-UNLP, Paseo del Bosque s/n, B1900FWA, Argentina; Departamento de Física - CFM - Universidade Federal de Santa Catarina, PO BOx 476, 88040-900, Florianópolis, SC, Brazil; Valongo Observatory, Federal University of Rio de Janeiro, Ladeira Pedro Antonio 43, Saude Rio de Janeiro, RJ, 20080-090, Brazil; Centro Brasileiro de Pesquisas Físicas, Rua Dr Xavier Sigaud 150, CEP 22290-180, Rio de Janeiro, RJ, Brazil; Universidade de São Paulo, IAG, Rua do Matão 1226, Sao Paulo, SP, Brazil; Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales y Ciclo Básico Común, Buenos Aires, Argentina; CONICET-Universidad de Buenos Aires, Instituto de Astronomía y Física del Espacio (IAFE), Buenos Aires, Argentina; Cambridge Survey Astronomical Unit (CASU), Institute of Astronomy, Madingley Road, Cambridge CB3 0HA, UK; Observatório Nacional, Rua General José Cristino, 77, São Cristóvão, 20921-400 Rio de Janeiro, RJ, Brazil; et al. (Monthly Notices of the Royal Astronomical Society, 2024-03-01)
    The Fornax galaxy cluster is the richest nearby (D ~ 20 Mpc) galaxy association in the southern sky. As such, it provides a wealth of oportunities to elucidate on the processes where environment holds a key role in transforming galaxies. Although it has been the focus of many studies, Fornax has never been explored with contiguous homogeneous wide-field imaging in 12 photometric narrow- and broad-bands like those provided by the Southern Photometric Local Universe Survey (S-PLUS). In this paper we present the S-PLUS Fornax Project (S+FP) that aims to comprehensively analyse the galaxy content of the Fornax cluster using S-PLUS. Our data set consists of 106 S-PLUS wide-field frames (FoV~1.4 ×1.4 deg<SUP>2</SUP>) observed in five SDSS-like ugriz broad-bands and seven narrow-bands covering specific spectroscopic features like [OII], CaII H+K, Hδ, G-band, Mg b triplet, Hα, and the CaII triplet. Based on S-PLUS specific automated photometry, aimed at correctly detecting Fornax galaxies and globular clusters in S-PLUS images, our dataset provides the community with catalogues containing homogeneous 12-band photometry for ~3 × 10<SUP>6</SUP> resolved and unresolved objects within a region extending over ~208 deg<SUP>2</SUP> (~5 R<SUB>vir</SUB> in RA) around Fornax' central galaxy, NGC 1399. We further explore the EAGLE and ILLUSTRISTNG cosmological simulations to identify 45 Fornax-like clusters and generate mock images on all 12 S-PLUS bands of these structures down to galaxies with M<SUB>⋆</SUB> ≥ 10<SUP>8</SUP> M<SUB>⊙</SUB>. The S+FP dataset we put forward in this first paper of a series will enable a variety of studies some of which are briefly presented.
  • EC 19529-4430: SALT identifies the most carbon- and metal-poor extreme helium star

    Armagh Observatory and Planetarium, College Hill, Armagh BT61 9DG, UK; Armagh Observatory and Planetarium, College Hill, Armagh BT61 9DG, UK; School of Mathematics and Physics, Queen's University Belfast, Belfast BT7 1NN, UK; Australian Astronomical Optics - Macquarie, Faculty of Science and Engineering, Macquarie University, North Ryde, NSW 2113, Australia; Physics Department, University of Nebraska at Omaha, 6001 Dodge St, Omaha, NE 68182, USA; Jeffery, C. S.; Scott, L. J. A.; Philip Monai, A.; Miszalski, B.; Woolf, V. M. (Monthly Notices of the Royal Astronomical Society, 2024-05-01)
    EC 19529-4430 was identified as a helium-rich star in the Edinburgh-Cape (EC) Survey of faint-blue objects and subsequently resolved as a metal-poor extreme helium (EHe) star in the Southern African Large Telescope (SALT) survey of chemically peculiar hot subdwarfs. This paper presents a fine analysis of the SALT high-resolution spectrum. EC 19529-4430 has $T_{\rm eff} = 20\, 700 \pm 250$ K, $\log g /{\rm cm\, s^{-2}} = 3.49\pm 0.03$, and an overall metallicity some 1.3 dex below solar; surface hydrogen is $\approx 0.5~{{\ \rm per\ cent}}$ by number. The surface CNO ratio 1:100:8 implies that the surface consists principally of CNO-processed helium and makes EC 19529-4430 the coolest known carbon-poor and nitrogen-rich EHe star. Metal-rich analogues include V652 Her and GALEX J184559.8-413827. Kinematically, its retrograde orbit indicates membership of the Galactic halo. No pulsations were detected in TESS photometry and there is no evidence for a binary companion. EC 19529-4430 most likely formed from the merging of two helium white dwarfs, which themselves formed as a binary system some 11 Gyr ago.
  • Predicting the heaviest black holes below the pair instability gap

    Armagh Observatory and Planetarium (AOP), Armagh, College Hill, BT61 9DB, UK; School of Maths and Physics, Queen's University Belfast, Northern Ireland, University Road, BT7 1NN, UK; Armagh Observatory and Planetarium (AOP), Armagh, College Hill, BT61 9DB, UK; Winch, Ethan R. J.; Vink, Jorick S.; Higgins, Erin R.; Sabhahitf, Gautham N. (Monthly Notices of the Royal Astronomical Society, 2024-04-01)
    Traditionally, the pair instability (PI) mass gap is located between 50 and 130 M<SUB>⊙</SUB>, with stellar mass black holes (BHs) expected to 'pile up' towards the lower PI edge. However, this lower PI boundary is based on the assumption that the star has already lost its hydrogen (H) envelope. With the announcement of an 'impossibly' heavy BH of 85 M<SUB>⊙</SUB> as part of GW 190521 located inside the traditional PI gap, we realized that blue supergiant (BSG) progenitors with small cores but large hydrogen envelopes at low metallicity (Z) could directly collapse to heavier BHs than had hitherto been assumed. The question of whether a single star can produce such a heavy BH is important, independent of gravitational wave events. Here, we systematically investigate the masses of stars inside the traditional PI gap by way of a grid of 336 detailed MESA stellar evolution models calculated across a wide parameter space, varying stellar mass, overshooting, rotation, semiconvection, and Z. We evolve low Z stars in the range 10<SUP>-3</SUP> &lt; Z/Z<SUB>⊙</SUB> &lt; Z<SUB>SMC</SUB>, making no prior assumption regarding the mass of an envelope, but instead employing a wind mass-loss recipe to calculate it. We compute critical carbon-oxygen and helium core masses to determine our lower limit to PI physics, and we provide two equations for M<SUB>core</SUB> and M<SUB>final</SUB> that can also be of use for binary population synthesis. Assuming the H envelope falls into the BH, we confirm the maximum BH mass below PI is M<SUB>BH</SUB> ≃ 93.3 M<SUB>⊙</SUB>. Our grid allows us to populate the traditional PI gap, and we conclude that the distribution of BHs above the traditional boundary is not solely due to the shape of the initial mass function, but also to the same stellar interior physics (i.e. mixing) that which sets the BH maximum.
  • The Magnetic Field in the Colliding Filaments G202.3+2.5

    Shanghai Astronomical Observatory, Chinese Academy of Sciences, No. 80 Nandan Road, Xuhui, Shanghai 200030, People's Republic of China; , ,; National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo, 181-8588, Japan; Shanghai Astronomical Observatory, Chinese Academy of Sciences, No. 80 Nandan Road, Xuhui, Shanghai 200030, People's Republic of China; , ,; Shanghai Astronomical Observatory, Chinese Academy of Sciences, No. 80 Nandan Road, Xuhui, Shanghai 200030, People's Republic of China; , ,; Université de Franche-Comté, CNRS, Institut UTINAM, OSU THETA, F-25000 Besançon, France; National Astronomical Observatories, Chinese Academy of Sciences, A20 Datun Road, Chaoyang, Beijing 100101, People's Republic of China; Department of Physics, P.O. Box 64, FI-00014, University of Helsinki, Finland; Gemini Observatory/NSF's NOIRLab, 670 N. A'ohoku Place, Hilo, HI 96720, USA; Center for Astrophysics ∣ Harvard &amp; Smithsonian 60 Garden Street, Cambridge, MA 02138, USA; Academia Sinica Institute of Astronomy and Astrophysics No. 1, Section 4, Roosevelt Road, Taipei 10617, Taiwan (R.O.C.); IRAP, Université de Toulouse, CNRS 9 avenue du Colonel Roche, BP 44346, F-31028 Toulouse Cedex 4, France; et al. (The Astrophysical Journal, 2024-03-01)
    We observe the magnetic field morphology toward a nearby star-forming filamentary cloud, G202.3+2.5, using James Clerk Maxwell Telescope/POL-2 850 μm thermal dust polarization observations with an angular resolution of 14.″4 (∼0.053 pc). The average magnetic field orientation is found to be perpendicular to the filaments, while showing different behaviors in the four subregions, suggesting various effects from the filaments' collision in these subregions. With the kinematics obtained by the ${{{\rm{N}}}_{2}{\rm{H}}}^{+}$ observation by IRAM, we estimate the plane-of-sky magnetic field strength by two methods, the classical Davis–Chandrasekhar–Fermi (DCF) method and the angular dispersion function (ADF) method, giving B <SUB>pos,dcf</SUB> and B <SUB>pos,adf</SUB> of ∼90 and ∼53 μG. We study the relative importance between the gravity (G), magnetic field (B), and turbulence (T) in the four subregions, and find G &gt; T &gt; B, G ≥ T &gt; B, G ∼ T &gt; B, and T &gt; G &gt; B in the north tail, west trunk, south root, and east wing, respectively. In addition, we investigate the projection effects on the DCF and ADF methods, based on a similar simulation case, and find the 3D magnetic field strength may be underestimated by a factor of ∼3 if applying the widely used statistical B <SUB>pos</SUB>-to-B <SUB>3D</SUB> factor when using the DCF or ADF methods, which may further underestimate/overestimate the related parameters.
  • On the Scarcity of Dense Cores (n &gt; 10<SUP>5</SUP> cm<SUP>‑3</SUP>) in High-latitude Planck Galactic Cold Clumps

    Kavli Institute for Astronomy and Astrophysics, Peking University, Beijing 100871, People's Republic of China; Department of Astronomy, School of Physics, Peking University, Beijing, 100871, People's Republic of China; Kavli Institute for Astronomy and Astrophysics, Peking University, Beijing 100871, People's Republic of China; Shanghai Astronomical Observatory, Chinese Academy of Sciences, 80 Nandan Road, Shanghai 200030, People's Republic of China; Armagh Observatory and Planetarium, College Hill, Armagh, BT61 9DB, UK; Department of Physics, University of Helsinki, P.O. Box 64, FI-00014 Helsinki, Finland; Yunnan Observatories, Chinese Academy of Sciences, 396 Yangfangwang, Guandu District, Kunming, 650216, People's Republic of China; Chinese Academy of Sciences South America Center for Astronomy, National Astronomical Observatories, CAS, Beijing 100101, People's Republic of China; Departamento de Astronomía, Universidad de Chile, Las Condes, 7591245 Santiago, Chile; NRC Herzberg Astronomy and Astrophysics, 5071 West Saanich Road, Victoria, BC, V9E 2E7, Canada; Department of Physics and Astronomy, University of Victoria, 3800 Finnerty Road, Elliot Building, Victoria, BC, V8P 5C2, Canada; Jet Propulsion Laboratory, California Institute of Technology, Pasadena CA 91109, USA; Departamento de Astronomía, Universidad de Chile, Las Condes, 7591245 Santiago, Chile; Indian Institute of Astrophysics, II Block, Koramangala, Bengaluru 560034, India; et al. (The Astrophysical Journal, 2024-03-01)
    High-latitude (∣b∣ &gt; 30°) molecular clouds have virial parameters that exceed 1, but whether these clouds can form stars has not been studied systematically. Using JCMT SCUBA-2 archival data, we surveyed 70 fields that target high-latitude Planck Galactic cold clumps (HLPCs) to find dense cores with density of 10<SUP>5</SUP>–10<SUP>6</SUP> cm<SUP>‑3</SUP> and size of &lt;0.1 pc. The sample benefits from both the representativeness of the parent sample and its coverage of the densest clumps at the high column density end (&gt;1 × 10<SUP>21</SUP> cm<SUP>‑2</SUP>). At an average rms of 15 mJy beam<SUP>‑1</SUP>, we detected Galactic dense cores in only one field, G6.04+36.77 (L183) while also identifying 12 extragalactic objects and two young stellar objects. Compared to the low-latitude clumps, dense cores are scarce in HLPCs. With synthetic observations, the densities of cores are constrained to be n <SUB> c </SUB> ≲ 10<SUP>5</SUP> cm<SUP>‑3</SUP> should they exist in HLPCs. Low-latitude clumps, Taurus clumps, and HLPCs form a sequence where a higher virial parameter corresponds to a lower dense-core detection rate. If HLPCs were affected by the Local Bubble, the scarcity should favor turbulence-inhibited rather than supernova-driven star formation. Studies of the formation mechanism of the L183 molecular cloud are warranted.
  • Predicting the Heaviest Black Holes below the Pair Instability Gap

    Armagh Observatory and Planetarium (AOP), Armagh, College Hill, BT61 9DB; School of Maths and Physics, Queen's University Belfast, Northern Ireland, University Road, BT7 1NN; Armagh Observatory and Planetarium (AOP), Armagh, College Hill, BT61 9DB; Winch, Ethan R. J.; Vink, Jorick S.; Higgins, Erin R.; Sabhahit, Gautham N. (Monthly Notices of the Royal Astronomical Society, 2024-02-01)
    Traditionally, the pair instability (PI) mass gap is located between 50 and 130 M<SUB>⊙</SUB>, with stellar mass black holes (BHs) expected to pile up towards the lower PI edge. However, this lower PI boundary is based on the assumption that the star has already lost its hydrogen (H) envelope. With the announcement of an impossibly heavy BH of 85 M<SUB>⊙</SUB> as part of GW 190521 located inside the traditional PI gap, we realised that blue supergiant (BSG) progenitors with small cores but large Hydrogen envelopes at low metallicity (Z) could directly collapse to heavier BHs than had hitherto been assumed. The question of whether a single star can produce such a heavy BH is important, independent of gravitational wave events. Here, we systematically investigate the masses of stars inside the traditional PI gap by way of a grid of 336 detailed MESA stellar evolution models calculated across a wide parameter space, varying stellar mass, overshooting, rotation, semi-convection, and Z. We evolve low Z stars in the range 10<SUP>-3</SUP> &lt; Z/Z<SUB>⊙</SUB> &lt; Z<SUB>SMC</SUB>, making no prior assumption regarding the mass of an envelope, but instead employing a wind mass loss recipe to calculate it. We compute critical Carbon-Oxygen and Helium core masses to determine our lower limit to PI physics, and we provide two equations for M<SUB>core</SUB> and M<SUB>final</SUB> that can also be of use for binary population synthesis. Assuming the H envelope falls into the BH, we confirm the maximum BH mass below PI is M<SUB>BH</SUB> ≃ 93.3 M<SUB>⊙</SUB>. Our grid allows us to populate the traditional PI gap, and we conclude that the distribution of BHs above the gap is not solely due to the shape of the initial mass function (IMF), but also to the same stellar interior physics (i.e. mixing) that which sets the BH maximum.
  • PDR Emission from the Arched-Filaments and Nearby Positions

    Instituto de Radioastronomía Milimétrica IRAM Av. Divina Pastora 7, 18012 Granada, Spain; I. Physikalisiches Institut, University of Cologne, Germany; University of Cincinnati, USA; Armagh Observatory and Planetarium, Northern Ireland; School of Physical Sciences, University of Adelaide, Australia; García, Pablo; Röllig, Markus; Abel, Nicholas; Steinke, Martin; Burton, Michael; et al. (The Multi-Messenger Astrophysics of the Galactic Centre, 2017-01-01)
    We investigate the physical conditions of the gas, atomic and molecular, in the filaments in the context of Photo-Dissociation Regions (PDRs) using the KOSMA-PDR mode of clumpy clouds. We also compare the [CII] vs. [NII] integrated intensity predictions in Abel et al. 2005 for HII regions and adjacent PDRs in the Galactic disk, and check for their applicability under the extreme physical conditions present in the GC. Our preliminary results show that observed integrated intensities are well reproduced by the PDR model. The gas is exposed to a relatively low Far-UV field between 10<SUP>2</SUP> - 10<SUP>3</SUP> Draine fields. The total volume hydrogen density is well constrained between 10<SUP>4</SUP> - 10<SUP>5</SUP> cm<SUP>-3</SUP>. The hydrogen ionization rate due to cosmic-rays varies between 10<SUP>-15</SUP> and 4× 10<SUP>-15</SUP> s<SUP>-1</SUP>, with the highest value ~ 10<SUP>-14</SUP> s<SUP>-1</SUP> found towards G0.07+0.04. Our results show that the line-of-sight contribution to the total distance of the filaments to the Arches Cluster is not negligible. The spatial distribution of the [CII]/[NII] ratio shows that the integrated intensity ratios are fairly homogeneously distributed for values below 10 in energy units. Calculations including variation on the [C/N] abundance ratio show that tight constraints on this ratio are needed to reproduce the observations.
  • Multimessenger science opportunities with mHz gravitational waves

    NASA Goddard Space Flight Center; Columbia University; Leiden University; Harvard University; The Pennsylvania State University; University of Cambridge; CITA, University of Toronto; California Institute of Technology; City University of New York/American Museum of Natural History; Princeton University; et al. (Bulletin of the American Astronomical Society, 2019-05-01)
    We review opportunities for multi-messenger science breakthroughs involving mHz gravitational waves with electromagnetic observations.
  • The Fornax3D Survey — A Magnitude-Limited Study of Galaxies in the Fornax Cluster with MUSE

    Armagh Observatory &amp; Planetarium, UK; INAF–Astronomical Observatory of Capodimonte, Napoli, Italy; -; Sarzi, M.; Iodice, E.; Fornax3D Collaboration (The Messenger, 2022-12-01)
    The Fornax galaxy cluster is an ideal nearby laboratory in which to study the impact of dense environments on the evolution of galaxies. The Fornax3D survey offers extended and deep integral-field spectroscopic observations for the brightest 33 galaxies within of virial radius of the Fornax cluster, obtained with the MUSE integral-field spectrograph, mounted on Unit Telescope 4 (Yepun) of ESO's Very Large Telescope in Chile. The Fornax3D data allowed us to reconstruct the formation of early-type galaxies in the cluster and to explore the link with spiral galaxies. Results have been published in 19 refereed papers since 2018. In this paper we review the broad goals of this campaign, its main results and the potential for future studies combining the MUSE data with the abundant multi-wavelength data coverage for Fornax.
  • Constraining the progenitor evolution of GW 150914

    Armagh Observatory, and Planetarium, BT61 9DG Armagh, College Hill, Northern Ireland,; Vink, Jorick S. (High-mass X-ray Binaries: Illuminating the Passage from Massive Binaries to Merging Compact Objects, 2019-12-01)
    One of the largest surprises from the LIGO results regarding the first gravitational wave detection (GW 150914) was the fact the black holes (BHs) were heavy, of order 30 - 40 M<SUB>⊙</SUB>. The most promising explanation for this obesity is that the BH-BH merger occurred at low metallicity (Z): when the iron (Fe) contents is lower this is expected to result in weaker mass loss during the Wolf-Rayet (WR) phase. We therefore critically evaluate the claims for the reasons of heavy BHs as a function of Z in the literature. Furthermore, weaker stellar winds might lead to more rapid stellar rotation, allowing WR and BH progenitor evolution in a chemically homogeneous manner. However, there is as yet no empirical evidence for more rapid rotation amongst WR stars in the low Z environment of the Magellanic Clouds. Due to the intrinsic challenge of determining WR rotation rates from emission lines, the most promising avenue to constrain rotation-rate distributions amongst various WR subgroups is through the utilisation of their emission lines in polarised light. We thus provide an overview of linear spectro-polarimetry observations of both single and binary WRs in the Galaxy, as well as the Large and Small Magellanic Clouds, at 50% and 20% of solar Z, respectively. Initial results suggest that the route of chemically homogeneous evolution (CHE) through stellar rotation is challenging, whilst the alternative of a post-LBV or common envelope evolution is more likely.
  • The coordinated radio and infrared survey for high-mass star formation - V. The CORNISH-South survey and catalogue

    Physics and Astronomy, University of Leeds, LS2 9JT, UK; Armagh Observatory and Planetarium, College Hill, BT61 9DB, UK; The National Radio Astronomy Observatory, Charlottesville, VA 22903, USA; Jodrell Bank Centre for Astrophysics, Department of Physics and Astronomy, University of Manchester, Manchester, M13 9PL, UK; The ALMA headquarters, Santiago, Alonso de Córdova 3107, Chile; School of Natural Sciences, College of Sciences and Engineering, University of Tasmania, Hobart 7001, TAS, Australia; Department of Physics, University of Oxford, Keble Road, Oxford, OX1 3RH, UK; Jodrell Bank Centre for Astrophysics, Department of Physics and Astronomy, University of Manchester, Manchester, M13 9PL, UK; Physikalisches Institut, University of Cologne, Zülpicher Str. 77, 50937 Köln, Germany; Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA; CSIRO Space and Astronomy, PO Box 1130, Bentley WA 6102, Australia; et al. (Monthly Notices of the Royal Astronomical Society, 2023-03-01)
    We present the first high spatial resolution radio continuum survey of the southern Galactic plane. The CORNISH project has mapped the region defined by 295° &lt; l &lt; 350°; |b| &lt; 1° at 5.5 GHz, with a resolution of 2.5 arcsec (FWHM). As with the CORNISH-North survey, this is designed to primarily provide matching radio data to the Spitzer GLIMPSE survey region. The CORNISH-South survey achieved a root mean square noise level of ~0.11 mJy beam<SUP>-1</SUP>, using the 6A configuration of the Australia Telescope Compact Array (ATCA). In this paper, we discuss the observations, data processing and measurements of the source properties. Above a 7σ detection limit, 4701 sources were detected, and their ensemble properties show similar distributions with their northern counterparts. The catalogue is highly reliable and is complete to 90 per cent at a flux density level of 1.1 mJy. We developed a new way of measuring the integrated flux densities and angular sizes of non-Gaussian sources. The catalogue primarily provides positions, flux density measurements, and angular sizes. All sources with IR counterparts at 8 μm have been visually classified, utilizing additional imaging data from optical, near-IR, mid-IR, far-IR, and sub-millimetre galactic plane surveys. This has resulted in the detection of 524 H II regions of which 255 are ultra-compact H II regions, 287 planetary nebulae, 79 radio stars, and 6 massive young stellar objects. The rest of the sources are likely to be extragalactic. These data are particularly important in the characterization and population studies of compact ionized sources such as UCHII regions and PNe towards the Galactic mid-plane.
  • COBRaS: The e-MERLIN 21 cm Legacy survey of Cygnus OB2

    Department of Physics &amp; Astronomy, University College London, Gower Street, London, WC1E 6BT, UK; Department of Physics &amp; Astronomy, University College London, Gower Street, London, WC1E 6BT, UK; Astrophysics Group, Cavendish Laboratory, University of Cambridge, Cambridge, UK; Royal Observatory of Belgium, Ringlaan 3, 1180, Brussels, Belgium; Harvard-Smithsonian Centre for Astrophysics, 60 Garden Street, Cambridge, MA, 02138, USA; Jeremiah Horrocks Institute, University of Central Lancashire, Preston, PR1 2HE, UK; Faculty of Computing, Engineering and Science, University of South Wales, Pontypridd, CF37 1DL, UK; UK ARC Node, JBCA, Alan Turing Building, University of Manchester, M13 9PL, Manchester, UK; School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK; Astrophysics Group, Leonard-Jones Building, Keele University, Staffordshire, ST5 5BG, UK; Department of Physical Sciences, The Open University, Walton Hall, Milton Keynes, MK7 6AA, UK; Dominion Radio Astrophysical Observatory, National Research Council Canada, PO Box 248, Penticton, BC V2A 6J9, Canada; ALMA, Alonso Cordoba 3107, 7630355, Vitacura, Chile; et al. (Astronomy and Astrophysics, 2020-05-01)
    Context. The role of massive stars is central to an understanding of galactic ecology. It is important to establish the details of how massive stars provide radiative, chemical, and mechanical feedback in galaxies. Central to these issues is an understanding of the evolution of massive stars, and the critical role of mass loss via strongly structured winds and stellar binarity. Ultimately, and acting collectively, massive stellar clusters shape the structure and energetics of galaxies. <BR /> Aims: We aim to conduct high-resolution, deep field mapping at 21 cm of the core of the massive Cygnus OB2 association and to characterise the properties of the massive stars and colliding winds at this waveband. <BR /> Methods: We used seven stations of the e-MERLIN radio facility, with its upgraded bandwidth and enhanced sensitivity to conduct a 21 cm census of Cygnus OB2. Based on 42 hours of observations, seven overlapping pointings were employed over multiple epochs during 2014 resulting in 1σ sensitivities down to ∼21 μJy and a resolution of ∼180 mas. <BR /> Results: A total of 61 sources are detected at 21 cm over a ∼0.48° × 0.48° region centred on the heart of the Cyg OB2 association. Of these 61 sources, 33 are detected for the first time. We detect a number of previously identified sources including four massive stellar binary systems, two YSOs, and several known X-ray and radio sources. We also detect the LBV candidate (possible binary system) and blue hypergiant star of Cyg OB2 #12. <BR /> Conclusions: The 21 cm observations secured in the COBRaS Legacy project provide data to constrain conditions in the outer wind regions of massive stars; determine the non-thermal properties of massive interacting binaries; examine evidence for transient sources, including those associated with young stellar objects; and provide unidentified sources that merit follow-up observations. The 21 cm data are of lasting value and will serve in combination with other key surveys of Cyg OB2, including Chandra and Spitzer.
  • Environmental conditions shaping star formation: the Carina Nebula

    Leiden Observatory, Leiden University, P.O. Box 9513, NL-2300 RA Leiden, the Netherlands; Joint ALMA Observatory, Alonso de Córdova 3107, Vitacura, Santiago, Chile; National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903, USA; Sydney Institute for Astronomy (SIfA), School of Physics, University of Sydney, NSW 2006, Sydney, Australia; Armagh Observatory and Planetarium, College Hill, Armagh BT61 9DG, UK; Contreras, Y.; Rebolledo, D.; Breen, S. L.; Green, A. J.; Burton, M. G. (Monthly Notices of the Royal Astronomical Society, 2019-02-01)
    Using the Mopra telescope, we have targeted 61 regions in the Carina Nebula, covering an area of 1.5 deg<SUP>2</SUP>, of bright and compact 870 μm dust continuum emission for molecular line emission from a host of 16 spectral lines at 3 mm, including several dense gas tracers. We found that the clumps detected in Carina in general have in average higher temperatures (27 K compared to 21 K), and lower masses (214 M<SUB>⊙</SUB> compared to 508 M<SUB>⊙</SUB>) than clumps located at a similar distance to us in the Galactic plane. We compare the properties of the molecular line emission of these clumps with the MALT90 survey, finding that the detection rates of the molecular lines are similar to MALT90 clumps that are classified as photodissociation regions. However, most of the clumps located within 10 arcmin of η Carina have little molecular line emission detected in our observations. Given the lack of maser detection in the Carina region, we also compared the properties of the clumps in Carina to those of Galactic clumps associated with 6.7-GHz methanol masers. We found that the clumps in Carina are warmer, less massive, and show less emission from the four most commonly detected molecules, HCO<SUP>+</SUP>, N<SUB>2</SUB>H<SUP>+</SUP>, HCN, and HNC, compared to clumps associated with masers in the Galactic Plane. Overall our results are consistent with the scenario in which the high radiation field of η Carina is dramatically affecting its local environment, and therefore the chemical composition of the dense clumps.
  • Scientific Goals of the Kunlun Infrared Sky Survey (KISS)

    School of Physics, University of New South Wales, Sydney, NSW 2052, Australia; Armagh Observatory and Planetarium, College Hill, Armagh, BT61 9DG, Northern Ireland, UK; Australian Astronomical Observatory, 105 Delhi Road, North Ryde, NSW 2113, Australia; Centre for Astrophysics and Supercomputing, Swinburne University of Technology, PO Box 218, Mail Number H29, Hawthorn, VIC 3122, Australia; ARC Centre of Excellence for All-sky Astrophysics (CAASTRO), Sydney, NSW 2006, Australia; Australian National University, Canberra, ACT 2611, Australia; Purple Mountain Observatory, Chinese Academy of Sciences, 2 West Beijing Road, Nanjing 210008, China; School of Astronomy and Space Science, Nanjing University, Nanjing 210008, China; Nanjing Institute of Astronomical Optics &amp; Technology, Chinese Academy of Sciences, 188 Bancang Street, Nanjing 210042, China; School of Physics, University of New South Wales, Sydney, NSW 2052, Australia; Centre for Astrophysics and Supercomputing, Swinburne University of Technology, PO Box 218, Mail Number H29, Hawthorn, VIC 3122, Australia; Purple Mountain Observatory, Chinese Academy of Sciences, 2 West Beijing Road, Nanjing 210008, China; Texas A&amp;M University, College Station, Texas 77843, USA; et al. (Publications of the Astronomical Society of Australia, 2016-09-01)
    The high Antarctic plateau provides exceptional conditions for infrared observations on account of the cold, dry and stable atmosphere above the ice surface. This paper describes the scientific goals behind the first program to examine the time-varying universe in the infrared from Antarctica - the Kunlun Infrared Sky Survey (KISS). This will employ a 50cm telescope to monitor the southern skies in the 2.4μmK <SUB>dark</SUB> window from China's Kunlun station at Dome A, on the summit of the Antarctic plateau, through the uninterrupted 4-month period of winter darkness. An earlier paper discussed optimisation of the K <SUB>dark</SUB> filter for sensitivity (Li et al. 2016). This paper examines the scientific program for KISS. We calculate the sensitivity of the camera for the extrema of observing conditions that will be encountered. We present the parameters for sample surveys that could then be carried out for a range of cadences and sensitivities. We then discuss several science programs that could be conducted with these capabilities, involving star formation, brown dwarfs and hot Jupiters, exoplanets around M dwarfs, the terminal phases of stellar evolution, fast transients, embedded supernova searches, reverberation mapping of AGN, gamma ray bursts and the detection of the cosmic infrared background.
  • Gaia-ESO Survey: Gas dynamics in the Carina nebula through optical emission lines

    INAF-Osservatorio Astronomico di Palermo G.S.Vaiana, Piazza del Parlamento 1, 90134, Palermo, Italy; INAF-Osservatorio Astronomico di Palermo G.S.Vaiana, Piazza del Parlamento 1, 90134, Palermo, Italy; Dipartimento di Fisica e Chimica, Università di Palermo, Piazza del Parlamento 1, 90134, Palermo, Italy; INAF-Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50125, Firenze, Italy; INAF-Osservatorio Astronomico di Padova, Vicolo dell'Osservatorio 5, 35122, Padova, Italy; Armagh Observatory, College Hill, Armagh, BT61 9DG, UK; School of Mathematics &amp; Physics, Queen's University Belfast, Belfast, BT61 7NN, UK; Centro de Astrobiología (CSIC-INTA), ESAC campus, Camino bajo del castillo s/n, 28 692 Villanueva de la Cañada, Madrid, Spain; Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge, CB3 0HA, UK; Instituto de Astrofísica de Andalucía-CSIC, Apdo. 3004, 18080, Granada, Spain; Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge, CB3 0HA, UK; Moscow MV Lomonosov State University, Sternberg Astronomical Institute, 119992, Moscow, Russia; INAF-Osservatorio Astrofisico di Catania, via S. Sofia 78, 95123, Catania, Italy; et al. (Astronomy and Astrophysics, 2016-06-01)
    <BR /> Aims: We present observations from the Gaia-ESO Survey in the lines of Hα, [N II], [S II], and He I of nebular emission in the central part of the Carina nebula. <BR /> Methods: We investigate the properties of the two already known kinematic components (approaching and receding), which account for the bulk of emission. Moreover, we investigate the features of the much less known low-intensity high-velocity (absolute RV &gt;50 km s<SUP>-1</SUP>) gas emission. <BR /> Results: We show that gas giving rise to Hα and He I emission is dynamically well correlated with but not identical to gas seen through forbidden-line emission. Gas temperatures are derived from line-width ratios, and densities from [S II] doublet ratios. The spatial variation of N ionization is also studied, and found to differ between the approaching and receding components. The main result is that the bulk of the emission lines in the central part of Carina arise from several distinct shell-like expanding regions, the most evident found around η Car, the Trumpler 14 core, and the star WR25. These shells are non-spherical and show distortions probably caused by collisions with other shells or colder, higher-density gas. Some of them are also partially obscured by foreground dust lanes, while very little dust is found in their interior. Preferential directions, parallel to the dark dust lanes, are found in the shell geometries and physical properties, probably related to strong density gradients in the studied region. We also find evidence that the ionizing flux emerging from η Car and the surrounding Homunculus nebula varies with polar angle. The high-velocity components in the wings of Hα are found to arise from expanding dust reflecting the η Car spectrum. <P />Based on observations collected with the FLAMES spectrograph at VLT/UT2 telescope (Paranal Observatory, ESO, Chile), for the Gaia-ESO Large Public Survey (program 188.B-3002).Full Tables 1-3 are only available at the CDS via anonymous ftp to <A href=http://cdsarc.u-strasbg.fr>http://cdsarc.u-strasbg.fr</A> (<A href=http://130.79.128.5>http://130.79.128.5</A>) or via <A href=http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/591/A74>http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/591/A74</A>
  • Constraints on interstellar dust models from extinction and spectro-polarimetry

    European Southern Observatory, Karl-Schwarzschild-Str. 2, D-85748, Garching b. München, Germany; Sobolev Astronomical Institute, St. Petersburg University, Universitetskii prosp. 28, St. Petersburg, 198504, Russia; Armagh Observator and Planetariumy, College Hill, Armagh, BT61 9DG, UK; Anton Pannekoek Institute for Astronomy, University of Amsterdam, NL-1090 GE, Amsterdam, The Netherlands; Siebenmorgen, R.; Voshchinnikov, N. V.; Bagnulo, S.; Cox, N. L. J. (Planetary and Space Science, 2017-12-01)
    We present polarisation spectra of seven stars in the lines-of-sight towards the Sco OB1 association. Our spectra were obtained within the framework of the Large Interstellar Polarization Survey carried out with the FORS instrument of the ESO VLT. We have modelled the wavelength-dependence of extinction and linear polarisation with a dust model for the diffuse interstellar medium which consists of a mixture of particles with size ranging from the molecular domain of 0.5 nm up to 350 nm. We have included stochastically heated small dust grains with radii between 0.5 and 6 nm made of graphite and silicate, as well as polycyclic aromatic hydrocarbon molecules (PAHs), and we have assumed that larger particles are prolate spheroids made of amorphous carbon and silicate. Overall, a dust model with eight free parameters best reproduces the observations, and is in agreement with cosmic abundance constraints. Reducing the number of free parameters leads to results that are inconsistent with the cosmic abundances of silicate and carbon. We found that aligned silicates are the dominant contributor to the observed polarisation, and that the polarisation spectra are best-fit by a lower limit of the equivolume sphere radius of aligned grains of 70-200 nm.
  • Two types of distribution of the gas velocity dispersion of MaNGA galaxies

    Main Astronomical Observatory, National Academy of Sciences of Ukraine, 27 Akademika Zabolotnoho St, 03680, Kiev, Ukraine; Faculty of Physics, Ludwig-Maximilians-Universitt, Scheinerstr. 1, 81679, Munich, Germany; Main Astronomical Observatory, National Academy of Sciences of Ukraine, 27 Akademika Zabolotnoho St, 03680, Kiev, Ukraine; Armagh Observatory and Planetarium, College Hill, Armagh BT61 9DG, Northern Ireland, UK; Kazan Federal University, 18 Kremlyovskaya St., 420008, Kazan, Russian Federation; Instituto de Astrofísica de Andalucía, CSIC, Apdo 3004, 18080, Granada, Spain; Pilyugin, L. S.; Zinchenko, I. A.; Lara-López, M. A.; Nefedyev, Y. A.; Vílchez, J. M. (Astronomy and Astrophysics, 2021-02-01)
    The distribution of the gas velocity dispersion σ across the images of 1146 MaNGA galaxies is analyzed. We find that there are two types of distribution of the gas velocity dispersion across the images of galaxies: (i) the distributions of 909 galaxies show a radial symmetry with or without the σ enhancement at the center (R distribution, radial symmetry in the σ distribution) and (ii) distributions with a band of enhanced σ along the minor axis in the images of 159 galaxies with or without the σ enhancement at the center (B distribution, band in the σ distribution). The σ distribution across the images of 78 galaxies cannot be reliable classified. We select 806 galaxies with the best defined characteristics (this sample includes 687 galaxies with R distribution and 119 galaxies with B distribution) and compare the properties of galaxies with R and B distributions. We find that the median value of the gas velocity dispersion σ<SUB>m</SUB> in galaxies with B distribution is higher by around 5 km s<SUP>-1</SUP>, on average, than that of galaxies with R distribution. The optical radius R<SUB>25</SUB> of galaxies with B distribution is lower by around 0.1 dex, on average, than that of galaxies with similar masses with R distribution. Thus the properties of a galaxy are related to the type of distribution of the gas velocity dispersion σ across its image. This suggests that the presence of the band of the enhanced gas velocity dispersion can be an indicator of a specific evolution (or a specific stage in the evolution) of a galaxy.

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