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Arxiv:1504.01453V1 [Astro-Ph.GA] 7 Apr 2015 Ences
Draft version August 9, 2018 A Preprint typeset using LTEX style emulateapj v. 03/07/07 THE WEAK CARBON MONOXIDE EMISSION IN AN EXTREMELY METAL POOR GALAXY, SEXTANS A ∗ Yong Shi1,2, 3, Junzhi Wang4,5, Zhi-Yu Zhang6, Yu Gao7,5,3, Lee Armus8, George Helou8, Qiusheng Gu1,2, 3, Sabrina Stierwalt9 Draft version August 9, 2018 ABSTRACT Carbon monoxide (CO) is one of the primary coolants of gas and an easily accessible tracer of molecular gas in spiral galaxies but it is unclear if CO plays a similar role in metal poor dwarfs. We carried out a deep observation with IRAM 30 m to search for CO emission by targeting the brightest far-IR peak in a nearby extremely metal poor galaxy, Sextans A, with 7% Solar metallicity. A weak CO J=1-0 emission is seen, which is already faint enough to place a strong constraint on the conversion factor (αCO) from the CO luminosity to the molecular gas mass that is derived from the spatially resolved dust mass map. The αCO is at least seven hundred times the Milky Way value. This indicates that CO emission is exceedingly weak in extremely metal poor galaxies, challenging its role as a coolant in these galaxies. Subject headings: galaxies: dwarf – submillimeter: ISM – galaxies: ISM 1. INTRODUCTION 2013) in low metallicity environments. Probing CO emis- Stars form out of molecular clouds (Kennicutt 1998; sion at lower metallicities establishes if CO emission can Gao & Solomon 2004). The efficient cooling of molec- be an efficient gas coolant and effective tracer of molec- ular gas is the prerequisite for gas collapse and star ular gas in metal poor galaxies both locally and in early formation. -
Formation of an Ultra-Diffuse Galaxy in the Stellar Filaments of NGC 3314A
A&A 652, L11 (2021) Astronomy https://doi.org/10.1051/0004-6361/202141086 & c ESO 2021 Astrophysics LETTER TO THE EDITOR Formation of an ultra-diffuse galaxy in the stellar filaments of NGC 3314A: Caught in the act? Enrichetta Iodice1 , Antonio La Marca1, Michael Hilker2, Michele Cantiello3, Giuseppe D’Ago4, Marco Gullieuszik5, Marina Rejkuba2, Magda Arnaboldi2, Marilena Spavone1, Chiara Spiniello6, Duncan A. Forbes7, Laura Greggio5, Roberto Rampazzo5, Steffen Mieske8, Maurizio Paolillo9, and Pietro Schipani1 1 INAF-Astronomical Observatory of Capodimonte, Salita Moiariello 16, 80131 Naples, Italy e-mail: [email protected] 2 European Southern Observatory, Karl-Schwarzschild-Strasse 2, 85748 Garching bei Muenchen, Germany 3 INAF-Astronomical Observatory of Abruzzo, Via Maggini, 64100 Teramo, Italy 4 Instituto de Astrofísica, Facultad de Fisica, Pontificia Universidad Católica de Chile, Av. Vicuña Mackenna 4860, 7820436 Macul, Santiago, Chile 5 INAF-Osservatorio Astronomico di Padova, Vicolo dell’Osservatorio 5, 35122 Padova, Italy 6 Department of Physics, University of Oxford, Denys Wilkinson Building, Keble Road, Oxford OX1 3RH, UK 7 Centre for Astrophysics and Supercomputing, Swinburne University of Technology, Hawthorn, Victoria 3122, Australia 8 European Southern Observatory, Alonso de Cordova 3107, Vitacura, Santiago, Chile 9 University of Naples “Federico II”, C.U. Monte Sant’Angelo, Via Cinthia, 80126 Naples, Italy Received 14 April 2021 / Accepted 9 July 2021 ABSTRACT The VEGAS imaging survey of the Hydra I cluster has revealed an extended network of stellar filaments to the south-west of the spiral galaxy NGC 3314A. Within these filaments, at a projected distance of ∼40 kpc from the galaxy, we discover an ultra-diffuse galaxy −2 (UDG) with a central surface brightness of µ0;g ∼ 26 mag arcsec and effective radius Re ∼ 3:8 kpc. -
Hubble Space Telescope Observer’S Guide Winter 2021
HUBBLE SPACE TELESCOPE OBSERVER’S GUIDE WINTER 2021 In 2021, the Hubble Space Telescope will celebrate 31 years in operation as a powerful observatory probing the astrophysics of the cosmos from Solar system studies to the high-redshift universe. The high-resolution imaging capability of HST spanning the IR, optical, and UV, coupled with spectroscopic capability will remain invaluable through the middle of the upcoming decade. HST coupled with JWST will enable new innovative science and be will be key for multi-messenger investigations. Key Science Threads • Properties of the huge variety of exo-planetary systems: compositions and inventories, compositions and characteristics of their planets • Probing the stellar and galactic evolution across the universe: pushing closer to the beginning of galaxy formation and preparing for coordinated JWST observations • Exploring clues as to the nature of dark energy ACS SBC absolute re-calibration (Cycle 27) reveals 30% greater • Probing the effect of dark matter on the evolution sensitivity than previously understood. More information at of galaxies http://www.stsci.edu/contents/news/acs-stans/acs-stan- • Quantifying the types and astrophysics of black holes october-2019 of over 7 orders of magnitude in size WFC3 offers high resolution imaging in many bands ranging from • Tracing the distribution of chemicals of life in 2000 to 17000 Angstroms, as well as spectroscopic capability in the universe the near ultraviolet and infrared. Many different modes are available for high precision photometry, astrometry, spectroscopy, mapping • Investigating phenomena and possible sites for and more. robotic and human exploration within our Solar System COS COS2025 initiative retains full science capability of COS/FUV out to 2025 (http://www.stsci.edu/hst/cos/cos2025). -
A High Stellar Velocity Dispersion and ~100 Globular Clusters for the Ultra
San Jose State University From the SelectedWorks of Aaron J. Romanowsky 2016 A High Stellar Velocity Dispersion and ~100 Globular Clusters for the Ultra-Diffuse Galaxy Dragonfly 44 Pieter van Dokkum, Yale University Roberto Abraham, University of Toronto Jean P. Brodie, University of California Observatories Charlie Conroy, Harvard-Smithsonian Center for Astrophysics Shany Danieli, Yale University, et al. Available at: https://works.bepress.com/aaron_romanowsky/117/ The Astrophysical Journal Letters, 828:L6 (6pp), 2016 September 1 doi:10.3847/2041-8205/828/1/L6 © 2016. The American Astronomical Society. All rights reserved. A HIGH STELLAR VELOCITY DISPERSION AND ∼100 GLOBULAR CLUSTERS FOR THE ULTRA-DIFFUSE GALAXY DRAGONFLY 44 Pieter van Dokkum1, Roberto Abraham2, Jean Brodie3, Charlie Conroy4, Shany Danieli1, Allison Merritt1, Lamiya Mowla1, Aaron Romanowsky3,5, and Jielai Zhang2 1 Astronomy Department, Yale University, New Haven, CT 06511, USA 2 Department of Astronomy & Astrophysics, University of Toronto, 50 St. George Street, Toronto, ON M5S 3H4, Canada 3 University of California Observatories, 1156 High Street, Santa Cruz, CA 95064, USA 4 Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA, USA 5 Department of Physics and Astronomy, San José State University, San Jose, CA 95192, USA Received 2016 June 20; revised 2016 July 14; accepted 2016 July 15; published 2016 August 25 ABSTRACT Recently a population of large, very low surface brightness, spheroidal galaxies was identified in the Coma cluster. The apparent survival of these ultra-diffuse galaxies (UDGs) in a rich cluster suggests that they have very high masses. Here, we present the stellar kinematics of Dragonfly44, one of the largest Coma UDGs, using a 33.5 hr fi +8 -1 integration with DEIMOS on the Keck II telescope. -
The ARAUCARIA Project – First Observations of Blue Supergiants in NGC 3109
Reports from Observers The ARAUCARIA Project – First Observations of Blue Supergiants in NGC 3109 Chris Evans1 Fabio Bresolin Miguel Urbaneja Grzegorz Pietrzyn´ski 3,4 Wolfgang Gieren 3 Rolf-Peter Kudritzki 1 United Kingdom Astronomy Technology Centre, Edinburgh, United Kingdom Institute for Astronomy, University of Hawaii, USA 3 Universidad de Concepción, Chile 4 Warsaw University Observatory, Poland NGC 3109 is an irregular galaxy at the edge of the Local Group at a distance of 1.3 Mpc. Here we present new VLT observations of its young, massive star population, which have allowed us to probe stellar abundances and kinemat- ics for the first time. The mean oxygen abundance obtained from early B-type supergiants confirms suggestions that NGC 3109 is a large Magellanic Irregular Figure 1: Part of the V-band FORS pre-image of our NGC 3109 is very metal poor. In this at 1.3 Mpc, which puts it at the outer edge most western field, with the targets encircled. NGC 3109 is approximately edge-on and the FORS context we advocate studies of the stel- of the Local Group. Using FORS in the targets are well sampled along both the major lar population of NGC 3109 as a com- configurable MOS (multi-object spectros- and minor axes. pelling target for future Extremely Large copy) mode, we have observed 91 stars Telescopes (ELTs). in NGC 3109. These were observed in Example spectra are shown in Figure . 4 MOS configurations, using the 600 B Of our 91 targets, 1 are late O-type stars, grism (giving a common wavelength cov- ranging from O8 to O9.5 – such high- The ARAUCARIA Project is an ESO Large erage of l3900 to l4750 Å). -
The Violent ISM in Haro 11
Stockholm University Department of Astronomy LICENTIATE THESIS The violent ISM in Haro 11 Author: Veronica Menacho Menacho Department of Astronomy, The Oskar Klein Center, Stockholm University, AlbaNova, 106 91 Stockholm, Sweden Supervisor: Goran¨ Ostlin¨ Co-Supervisor: Arjan Bik January 10, 2019 Abstract This thesis introduces briefly physical processes operating in the ISM around massive stars and focuses on the impact strong stellar feedback has in creating large-scale structures in a galaxy. Stellar feedback is ubiquitous in star forming galaxies and its effect on the ISM depends strongly on the energy output from the most massive stars (M≥7 M ) and the properties of the surrounding gas. Starburst galaxies are among the most active in producing large amount of massive star clusters with stellar populations up to thousands of massive stars. In the first 4 Myr of the star clusters evolution, radiative feedback of the most massive stars (M≥30 M ) are at work. Large amount of ionizing photons are released to the ambient medium while radiative pressure compress the surrounding gas. At the same time their stellar winds inject continuously mechanical energy and momentum in their surrounding. This mechanical feedback is then at later ages, until ∼ 40 Myrs, maintained by supernova explosions from the less massive stars. Strong stellar feedback tends to develop large-scale structures such as bubbles, loops, fil- aments and outflows. These are transient structures and can be seen as imprints of how the released energy is clearing or has cleared paths in the ISM. Strong stellar feedback can have devastating consequences in dwarf galaxies due to their shallow gravitational potential. -
The Search for Living Worlds and the Connection to Our Cosmic Origins
The Search for Living Worlds and the Connection to Our Cosmic Origins Contact person: Prof Martin Barstow Address: Department of Physics & Astronomy, University of Leicester, UK Email: [email protected] Telephone: +44 116 252 3492 Imaging Earth 2.0. Simulation of the inner solar system viewed at visible wavelengths from a distance of 13 parsec with a LUVOIR telescope. The enormous glare from the central star has been suppressed with a coronagraph so the faint planets can be seen. The atmosphere of each planet can be probed with spectra to reveal its composition. Credit: L. Pueyo, M M. N’Diaye (STScI)/A. Roberge (NASA GSFC). The Search for Living Worlds – ESA Voyage 2050 White Paper Executive summary One of the most exciting scientific challenges is to detect Earth-like planets in the habitable zones of other stars in the galaxy and search for evidence of life. During the past 20 years the detection of exoplanets, orbiting stars beyond our own has moved from science fiction to science fact. From the first handful of gas giants, found through radial velocity studies, detection techniques have increased in sensitivity, finding smaller planets and diverse multi-planet systems. Through enhanced ground-based spectroscopic observations, transit detection techniques and the enormous productivity of the Kepler space mission, the number of confirmed planets has increased to more than 2000. There are several space missions, such as TESS (NASA), now operational, and PLATO (ESA), which will extend the parameter space for exoplanet discovery towards the regime of rocky earth- like planets and take the census of such bodies in the neighbourhood of the Solar System. -
Spatially Resolved Stellar Kinematics of the Ultra-Diffuse Galaxy Dragonfly 44
The Astrophysical Journal, 880:91 (26pp), 2019 August 1 https://doi.org/10.3847/1538-4357/ab2914 © 2019. The American Astronomical Society. All rights reserved. Spatially Resolved Stellar Kinematics of the Ultra-diffuse Galaxy Dragonfly 44. I. Observations, Kinematics, and Cold Dark Matter Halo Fits Pieter van Dokkum1 , Asher Wasserman2 , Shany Danieli1 , Roberto Abraham3 , Jean Brodie2 , Charlie Conroy4 , Duncan A. Forbes5, Christopher Martin6, Matt Matuszewski6, Aaron J. Romanowsky2,7 , and Alexa Villaume2 1 Astronomy Department, Yale University, 52 Hillhouse Avenue, New Haven, CT 06511, USA 2 University of California Observatories, 1156 High Street, Santa Cruz, CA 95064, USA 3 Department of Astronomy & Astrophysics, University of Toronto, 50 St. George Street, Toronto, ON M5S 3H4, Canada 4 Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA, USA 5 Centre for Astrophysics and Supercomputing, Swinburne University, Hawthorn, VIC 3122, Australia 6 Cahill Center for Astrophysics, California Institute of Technology, 1216 East California Boulevard, Mail Code 278-17, Pasadena, CA 91125, USA 7 Department of Physics and Astronomy, San José State University, San Jose, CA 95192, USA Received 2019 March 31; revised 2019 May 25; accepted 2019 June 5; published 2019 July 30 Abstract We present spatially resolved stellar kinematics of the well-studied ultra-diffuse galaxy (UDG) Dragonfly44, as determined from 25.3 hr of observations with the Keck Cosmic Web Imager. The luminosity-weighted dispersion +3 −1 within the half-light radius is s12= 33-3 km s , lower than what we had inferred before from a DEIMOS spectrum in the Hα region. There is no evidence for rotation, with Vmax áñ<s 0.12 (90% confidence) along the major axis, in possible conflict with models where UDGs are the high-spin tail of the normal dwarf galaxy distribution. -
Arxiv:1704.01678V2 [Astro-Ph.GA] 28 Jul 2017 Been Notoriously Difficult, Resulting Mostly in Upper Lim- Highest Escape Fractions Measured to Date Among Low- Its (E.G
Submitted: 3 March 2017 Preprint typeset using LATEX style AASTeX6 v. 1.0 MRK 71 / NGC 2366: THE NEAREST GREEN PEA ANALOG Genoveva Micheva1, M. S. Oey1, Anne E. Jaskot2, and Bethan L. James3 (Accepted 24 July 2017) 1University of Michigan, 311 West Hall, 1085 S. University Ave, Ann Arbor, MI 48109-1107, USA 2Department of Astronomy, Smith College, Northampton, MA 01063, USA 3STScI, 3700 San Martin Drive, Baltimore, MD 21218, USA ABSTRACT We present the remarkable discovery that the dwarf irregular galaxy NGC 2366 is an excellent analog of the Green Pea (GP) galaxies, which are characterized by extremely high ionization parameters. The similarities are driven predominantly by the giant H II region Markarian 71 (Mrk 71). We compare the system with GPs in terms of morphology, excitation properties, specific star-formation rate, kinematics, absorption of low-ionization species, reddening, and chemical abundance, and find consistencies throughout. Since extreme GPs are associated with both candidate and confirmed Lyman continuum (LyC) emitters, Mrk 71/NGC 2366 is thus also a good candidate for LyC escape. The spatially resolved data for this object show a superbubble blowout generated by mechanical feedback from one of its two super star clusters (SSCs), Knot B, while the extreme ionization properties are driven by the . 1 Myr-old, enshrouded SSC Knot A, which has ∼ 10 times higher ionizing luminosity. Very massive stars (> 100 M ) may be present in this remarkable object. Ionization-parameter mapping indicates the blowout region is optically thin in the LyC, and the general properties also suggest LyC escape in the line of sight. -
The Molecular Gas Reservoir of 6 Low-Metallicity Galaxies from the Herschel Dwarf Galaxy Survey a Ground-Based Follow-Up Survey of CO(1–0), CO(2–1), and CO(3–2)
A&A 564, A121 (2014) Astronomy DOI: 10.1051/0004-6361/201322096 & c ESO 2014 Astrophysics The molecular gas reservoir of 6 low-metallicity galaxies from the Herschel Dwarf Galaxy Survey A ground-based follow-up survey of CO(1–0), CO(2–1), and CO(3–2) D. Cormier1,S.C.Madden2, V. Lebouteiller2,S.Hony3, S. Aalto4, F. Costagliola4,5, A. Hughes3, A. Rémy-Ruyer2, N. Abel6, E. Bayet7, F. Bigiel1, J. M. Cannon8,R.J.Cumming9, M. Galametz10, F. Galliano2, S. Viti11,andR.Wu2 1 Institut für theoretische Astrophysik, Zentrum für Astronomie der Universität Heidelberg, Albert-Ueberle Str. 2, 69120 Heidelberg, Germany e-mail: [email protected] 2 Laboratoire AIM, CEA/DSM – CNRS – Université Paris Diderot, Irfu/Service d’Astrophysique, CEA Saclay, 91191 Gif-sur-Yvette, France 3 Max-Planck-Institute for Astronomy, Königstuhl 17, 69117 Heidelberg, Germany 4 Department of Earth and Space Sciences, Chalmers University of Technology, Onsala Space Observatory, 439 92 Onsala, Sweden 5 Instituto de Astrofísica de Andalucía, Glorieta de la Astronomía s/n, 18008 Granada, Spain 6 University of Cincinnati, Clermont College, Batavia OH 45103, USA 7 Sub-Dept. of Astrophysics, Dept. of Physics at University of Oxford, Denys Wilkinson Building, Keble Road, Oxford OX1 3RH, UK 8 Department of Physics & Astronomy, Macalester College, 1600 Grand Avenue, Saint Paul MN 55105, USA 9 Onsala Space Observatory, Chalmers University of Technology, 439 92 Onsala, Sweden 10 Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA, UK 11 Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, UK Received 17 June 2013 / Accepted 17 November 2013 ABSTRACT Context. -
And Ecclesiastical Cosmology
GSJ: VOLUME 6, ISSUE 3, MARCH 2018 101 GSJ: Volume 6, Issue 3, March 2018, Online: ISSN 2320-9186 www.globalscientificjournal.com DEMOLITION HUBBLE'S LAW, BIG BANG THE BASIS OF "MODERN" AND ECCLESIASTICAL COSMOLOGY Author: Weitter Duckss (Slavko Sedic) Zadar Croatia Pусскй Croatian „If two objects are represented by ball bearings and space-time by the stretching of a rubber sheet, the Doppler effect is caused by the rolling of ball bearings over the rubber sheet in order to achieve a particular motion. A cosmological red shift occurs when ball bearings get stuck on the sheet, which is stretched.“ Wikipedia OK, let's check that on our local group of galaxies (the table from my article „Where did the blue spectral shift inside the universe come from?“) galaxies, local groups Redshift km/s Blueshift km/s Sextans B (4.44 ± 0.23 Mly) 300 ± 0 Sextans A 324 ± 2 NGC 3109 403 ± 1 Tucana Dwarf 130 ± ? Leo I 285 ± 2 NGC 6822 -57 ± 2 Andromeda Galaxy -301 ± 1 Leo II (about 690,000 ly) 79 ± 1 Phoenix Dwarf 60 ± 30 SagDIG -79 ± 1 Aquarius Dwarf -141 ± 2 Wolf–Lundmark–Melotte -122 ± 2 Pisces Dwarf -287 ± 0 Antlia Dwarf 362 ± 0 Leo A 0.000067 (z) Pegasus Dwarf Spheroidal -354 ± 3 IC 10 -348 ± 1 NGC 185 -202 ± 3 Canes Venatici I ~ 31 GSJ© 2018 www.globalscientificjournal.com GSJ: VOLUME 6, ISSUE 3, MARCH 2018 102 Andromeda III -351 ± 9 Andromeda II -188 ± 3 Triangulum Galaxy -179 ± 3 Messier 110 -241 ± 3 NGC 147 (2.53 ± 0.11 Mly) -193 ± 3 Small Magellanic Cloud 0.000527 Large Magellanic Cloud - - M32 -200 ± 6 NGC 205 -241 ± 3 IC 1613 -234 ± 1 Carina Dwarf 230 ± 60 Sextans Dwarf 224 ± 2 Ursa Minor Dwarf (200 ± 30 kly) -247 ± 1 Draco Dwarf -292 ± 21 Cassiopeia Dwarf -307 ± 2 Ursa Major II Dwarf - 116 Leo IV 130 Leo V ( 585 kly) 173 Leo T -60 Bootes II -120 Pegasus Dwarf -183 ± 0 Sculptor Dwarf 110 ± 1 Etc. -
CURRENT AFFAIRS= 18-12-2019 International Migrants Day
CURRENT AFFAIRS= 18-12-2019 International Migrants Day International Migrants Day is celebrated on 18 December to raise awareness about the protection for migrants and refugees. The International Organisation for Migration (IOM) is calling an international community to come together and remember the migrants and refugees who have lost their lives or have disappeared while reaching a safe harbor. Government promises broadband access in all villages by 2022; launches National Broadband Mission. The government promised broadband access in all villages by 2022, as it launched the ambitious National Broadband Mission entailing stakeholder investment of Rs 7 lakh crore in the coming years. The mission will facilitate universal and equitable access to broadband services across the country, especially in rural and remote areas. It also involves laying of incremental 30 lakh route km of Optical Fiber Cable and increase in tower density from 0.42 to 1 tower per thousand of population by 2024. The mission unveiled by Communications Minister Ravi Shankar Prasad will also aim at significantly improving quality of services for mobile and internet. “By 2022, we will take broadband to all the villages of India.The number of towers in the country which is about 5.65 lakh will be increased to 10 lakh,” Prasad stated. The mission also envisages increasing fiberisation of towers to 70 per cent from 30 per cent at present. GEM launches National Outreach Programme – GEM Samvaad. A national outreach Programme, GeM Samvaad, was launched by Anup Wadhawan, Secretary, Department of Commerce, Ministry of Commerce & Industry, Go1vernment of India and Chairman, GeM in New Delhi.