Near-Infrared Spectroscopy of 20 New Chandra Sources in the Norma Arm
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Eclipse Newsletter
ECLIPSE NEWSLETTER The Eclipse Newsletter is dedicated to increasing the knowledge of Astronomy, Astrophysics, Cosmology and related subjects. VOLUMN 2 NUMBER 1 JANUARY – FEBRUARY 2018 PLEASE SEND ALL PHOTOS, QUESTIONS AND REQUST FOR ARTICLES TO [email protected] 1 MCAO PUBLIC NIGHTS AND FAMILY NIGHTS. The general public and MCAO members are invited to visit the Observatory on select Monday evenings at 8PM for Public Night programs. These programs include discussions and illustrated talks on astronomy, planetarium programs and offer the opportunity to view the planets, moon and other objects through the telescope, weather permitting. Due to limited parking and seating at the observatory, admission is by reservation only. Public Night attendance is limited to adults and students 5th grade and above. If you are interested in making reservations for a public night, you can contact us by calling 302-654- 6407 between the hours of 9 am and 1 pm Monday through Friday. Or you can email us any time at [email protected] or [email protected]. The public nights will be presented even if the weather does not permit observation through the telescope. The admission fees are $3 for adults and $2 for children. There is no admission cost for MCAO members, but reservations are still required. If you are interested in becoming a MCAO member, please see the link for membership. We also offer family memberships. Family Nights are scheduled from late spring to early fall on Friday nights at 8:30PM. These programs are opportunities for families with younger children to see and learn about astronomy by looking at and enjoying the sky and its wonders. -
SEDIGISM-ATLASGAL: Dense Gas Fraction and Star Formation Efficiency Across the Galactic Disk
MNRAS 000,1– ?? (2020) Preprint 4 December 2020 Compiled using MNRAS LATEX style file v3.0 SEDIGISM-ATLASGAL: Dense Gas Fraction and Star Formation Efficiency Across the Galactic Disk?† J. S. Urquhart1‡, C. Figura2, J. R. Cross1, M. R. A. Wells1, T. J. T. Moore3, D. J. Eden3, S. E. Ragan4, A. R. Pettitt5, A. Duarte-Cabral4, D. Colombo6, F. Schuller7;6, T. Csengeri8, M. Mattern9;6, H. Beuther10, K. M. Menten6, F. Wyrowski6, L. D. Anderson11;12;13, P.J. Barnes14, M. T. Beltrán15, S. J. Billington1, L. Bronfman16, A. Giannetti17, J. Kainulainen18, J. Kauffmann19 , M.-Y.Lee20, S. Leurini21, S.-N. X. Medina6, F. M. Montenegro22, M. Riener10, A. J. Rigby4, A. Sánchez-Monge23, P.Schilke23, E. Schisano24, A. Traficante24, M. Wienen25 Affiliations can be found after the references. Accepted XXX. Received YYY; in original form ZZZ ABSTRACT By combining two surveys covering a large fraction of the molecular material in the Galactic disk we investigate the role the spiral arms play in the star formation process. We have matched clumps identified by ATLASGAL with their parental GMCs as identified by SEDIGISM, and use these giant molecular cloud (GMC) masses, the bolometric luminosi- ties, and integrated clump masses obtained in a concurrent paper to estimate the dense gas fractions (DGFgmc = ∑Mclump=Mgmc) and the instantaneous star forming efficiencies (i.e., SFEgmc = ∑Lclump=Mgmc). We find that the molecular material associated with ATLASGAL clumps is concentrated in the spiral arms (∼60 per cent found within ±10 km s−1 of an arm). We have searched for variations in the values of these physical parameters with respect to their proximity to the spiral arms, but find no evidence for any enhancement that might be attributable to the spiral arms. -
University of Maryland Department of Physics and Astronomy
PROPAGATION OF COSMIC RAYS IN THE GALAXY R. R. Daniel Tata Institute of Fundamental Research Homi Bhabha Road, Bombay, India and S. A. Stephens* Department of Physics & Astronomy, University of Maryland and Goddard Space Flight Center, Greenbelt, Maryland, U.S.A. Technical Report No. 75-028 UNIVERSITY OF MARYLAND DEPARTMENT OF PHYSICS AND ASTRONOMY COLLEGE PARK, MARYLAND (NASA-CR-141190) PROPAGATION OF COSMIC RAYS N75-15580 IN THE GALAXY (Maryland Univ.) 208 p HC $7.25 CSCL 03B Unclas G3/93 05074 This is a preprint of research carried out at the University of Maryland. In order to promote the active exchange of research results, individuals and groups at your institution are encouraged to send their preprints to PREPRINT LIBRARY DEPARTMENT 'OF PHYSICS AND ASTRONOMY UNIVERSITY OF MARYLAND COLLEGE PARK, MARYLAND 20742 U.S.A. PROPAGATION OF COSMIC RAYS IN THE GALAXY R. R. Daniel Tata Institute of Fundamental Research Homi Bhabha Road, Bombay, India and S. A. Stephens* Department of Physics & Astronomy, University of Maryland and Goddard Space Flight Center, Greenbelt, Maryland, U.S.A. Technical Report No. 75-028 To appear in Space Science Reviews *on leave from Tata Institute of Fundamental Research, Bombay, India. CONTENTS 1. Introduction 1.1. Models of cosmic ray confinement 1.2. The galactic model for cosmic ray confinement 1.3. Scope of the present review 2. General description of the Galaxy 2.1. Dimensions and density 2.2. Structure 2.3. Interstellar gas 2.4. Magnetic fields 2.5. Radiation fields 3. Cosmic ray propagation in the Galaxy: Theoretical aspects 3.1. -
INTEGRAL AO-12 General Programme 27 May 2014
INTEGRAL AO-12 General Programme 27 May 2014 Normal Proposals Approved Proposal ID Title PI Country Category Approved Target Time Grade [ksec] 1220001 Regular and frequent INTEGRAL monitoring of the Galactic Bulge region Kuulkers Spain Galactic Astronomy Galactic Bulge region 529 A 1220009 Continued Observation of the Galactic Center Region with INTEGRAL Wilms Germany Galactic Astronomy Sgr A* 2000 A 1220024 Deeply X-raying the Local Universe with INTEGRAL Bottacini USA Extragalactic Astronomy 3 fields in Coma region 4000 A 1220034 INTEGRAL Earth Observations: Cosmic X-ray Background and Earth emission Türler Switzerland Nucleosynth. and diff. emission Earth/CXB 130 A 1220035 26Al line shift from the closest massive star group Krause Germany Nucleosynth. and diff. emission Sco/Cen region 3000 A 1220006 Massive Stars in the Orion Region Diehl Germany Nucleosynth. and diff. emission Orion region 1000 B 1220011 Regular INTEGRAL monitoring of the Crab Kuulkers Spain Galactic Astronomy Crab 540 B 1220014 Keeping watch over our Galaxy - the return of the GPS3 Bazzano Italy Galactic Astronomy Galactic Plane scans 1000 B 1220016 ISA: INTEGRAL Spiral Arms Monitoring Program Bodaghee USA Galactic Astronomy Norma/Perseus arm 600 B 1220017 ISA: INTEGRAL Spiral Arms Monitoring Program Bodaghee USA Galactic Astronomy Scutum/Sagittarius arm 600 B 1220018 Monitoring Known Black Hole Binaries in the Galactic Center Wilms Germany Galactic Astronomy Known BHB (DR) B 1220021 Broad view on high energy Galactic background: "Galactic Center" Sunyaev Russian Federation Nucleosynth. and diff. emission Latitude scans l=0 2000 B 1220022 Broad view on high energy Galactic background: "Norma Arm" Krivonos Russian Federation Nucleosynth. -
The SAI Catalog of Supernovae and Radial Distributions of Supernovae
Astronomy Letters, Vol. 30, No. 11, 2004, pp. 729–736. Translated from Pis’ma v Astronomicheski˘ı Zhurnal, Vol. 30, No. 11, 2004, pp. 803–811. Original Russian Text Copyright c 2004 by Tsvetkov, Pavlyuk, Bartunov. TheSAICatalogofSupernovaeandRadialDistributions of Supernovae of Various Types in Galaxies D. Yu. Tsvetkov*, N.N.Pavlyuk**,andO.S.Bartunov*** Sternberg Astronomical Institute, Universitetski ˘ı pr. 13, Moscow, 119992 Russia Received May 18, 2004 Abstract—We describe the Sternberg Astronomical Institute (SAI)catalog of supernovae. We show that the radial distributions of type-Ia, type-Ibc, and type-II supernovae differ in the central parts of spiral galaxies and are similar in their outer regions, while the radial distribution of type-Ia supernovae in elliptical galaxies differs from that in spiral and lenticular galaxies. We give a list of the supernovae that are farthest from the galactic centers, estimate their relative explosion rate, and discuss their possible origins. c 2004MAIK “Nauka/Interperiodica”. Key words: astronomical catalogs, supernovae, observations, radial distributions of supernovae. INTRODUCTION be found on the Internet. The most complete data are contained in the list of SNe maintained by the Cen- In recent years, interest in studying supernovae (SNe)has increased signi ficantly. Among other rea- tral Bureau of Astronomical Telegrams (http://cfa- sons, this is because SNe Ia are used as “standard www.harvard.edu/cfa/ps/lists/Supernovae.html)and candles” for constructing distance scales and for cos- the electronic version of the Asiago catalog mological studies, and because SNe Ibc may be re- (http://web.pd.astro.it/supern). lated to gamma ray bursts. -
V2487 Oph 1998: a Post Nova in an Intermediate Polar
EPJ Web of Conferences 64, 07002 (2014) DOI: 10.1051/epjconf/20146407002 C Owned by the authors, published by EDP Sciences, 2014 V2487 Oph 1998: a post nova in an intermediate polar Margarita Hernanz1;a 1Institute of Space Sciences - ICE (CSIC-IEEC), Campus UAB, Fac. Ciències, C5 par 2a pl., 08193 Bellaterra (Barcelona), Spain Abstract. V2487 Oph (Nova Oph 1998) is a classical nova that exploded in 1998. XMM-Newton observations performed between 2 and 9 years after the explosion showed emission related to restablished accretion, and indicative of a magnetic white dwarf. The spectrum looks like that of a cataclysmic variable of the intermediate polar type. Anyway, we don’t have yet a definitive confirmation of the intermediate polar character, through determination of spin and orbital periods. Although it is not the first nova exploding in a magnetic white dwarf, it is always challenging to reach explosive conditions when a stan- dard accretion disk can’t be formed, because of the magnetic field. In addition, V2487 Oph has been the first nova where a detection of X-rays - in the host binary system - has been reported prior to its eruption, in 1990 with the ROSAT satellite. V2487 Oph has been also detected in hard X-rays with INTEGRAL/IBIS and RXTE/PCA. Last but not least, V2487 Oph has been identified as a recurrent nova in 2008, since a prior eruption in 1900 has been reported through analysis of Harvard photographic plates. Therefore, it is expected to host a massive white dwarf and be a candidate for a type Ia supernova explo- sion. -
An Observational Argument Against Accretion in Magnetars
Astronomy & Astrophysics manuscript no. start c ESO 2020 September 30, 2020 An observational argument against accretion in magnetars V.Doroshenko1; 2, A. Santangelo1, V. F. Suleimanov1; 2; 3, and S. S. Tsygankov4; 2 1 Institut für Astronomie und Astrophysik, Sand 1, 72076 Tübingen, Germany 2 Space Research Institute of the Russian Academy of Sciences, Profsoyuznaya Str. 84/32, Moscow 117997, Russia 3 Astronomy Department, Kazan (Volga region) Federal University, Kremlyovskaya str. 18, 420008 Kazan, Russia 4 Department of Physics and Astronomy, FI-20014 University of Turku, Finland September 30, 2020 ABSTRACT The phenomenology of anomalous X-ray pulsars is usually interpreted within the paradigm of very highly magnetized neutron stars, also known as magnetars. According to this paradigm, the persistent emission of anomalous X-ray pulsars (AXPs) is powered by the decay of the magnetic field. However, an alternative scenario in which the persistent emission is explained through accretion is also discussed in literature. In particular, AXP 4U 0142+61 has been suggested to be either an accreting neutron star or a white dwarf. Here, we rule out this scenario based on the the observed X-ray variability properties of the source. We directly compare the observed power spectra of 4U 0142+61 and of two other magnetars, 1RXS J170849.0−400910 and 1E 1841−045 with that of the X-ray pulsar 1A 0535+262, and of the intermediate polar GK Persei. In addition, we include a bright young radio pulsar PSR B1509-58 for comparison. We show that, unlike accreting sources, no aperiodic variability within the expected frequency range is observed in the power density spectrum of the magnetars and the radio pulsar. -
Spectroscopy and Orbital Periods of Four Cataclysmic Variable Stars
Dartmouth College Dartmouth Digital Commons Open Dartmouth: Published works by Dartmouth faculty Faculty Work 10-1-2001 Spectroscopy and Orbital Periods of Four Cataclysmic Variable Stars John R. Thorstensen Dartmouth College Cynthia J. Taylor Dartmouth College Follow this and additional works at: https://digitalcommons.dartmouth.edu/facoa Part of the Stars, Interstellar Medium and the Galaxy Commons Dartmouth Digital Commons Citation Thorstensen, John R. and Taylor, Cynthia J., "Spectroscopy and Orbital Periods of Four Cataclysmic Variable Stars" (2001). Open Dartmouth: Published works by Dartmouth faculty. 1868. https://digitalcommons.dartmouth.edu/facoa/1868 This Article is brought to you for free and open access by the Faculty Work at Dartmouth Digital Commons. It has been accepted for inclusion in Open Dartmouth: Published works by Dartmouth faculty by an authorized administrator of Dartmouth Digital Commons. For more information, please contact [email protected]. Mon. Not. R. Astron. Soc. 326, 1235–1242 (2001) Spectroscopy and orbital periods of four cataclysmic variable stars John R. ThorstensenP and Cynthia J. Taylor Department of Physics and Astronomy, Dartmouth College, Hanover, NH 03755, USA Accepted 2001 May 2. Received 2001 May 2; in original form 2001 March 29 ABSTRACT We present spectroscopy and orbital periods Porb of four relatively little-studied cataclysmic variable stars. The stars and their periods are: AF Cam, Porb ¼ 0:324ð1Þ d (the daily cycle count is slightly ambiguous); V2069 Cyg (¼ RX J2123.714217), 0.311683(2) d; PG 09351075, 0.1868(3) d; and KUV 0358010614, 0.1495(6) d. V2069 Cyg and KUV 0358010614 both show He II l4686 emission comparable in strength to Hb. -
Nova V4743 Sagittarii 2002: an Intermediate Polar Candidate
Draft version March 30, 2021 A Preprint typeset using LTEX style emulateapj v. 6/22/04 NOVA V4743 SAGITTARII 2002: AN INTERMEDIATE POLAR CANDIDATE Tae W. Kang1, Alon Retter1, Alex Liu2, and Mercedes Richards1 1Dept. of Astronomy & Astrophysics, Penn State University, 525 Davey Lab, University Park, PA 16802; [email protected]; [email protected]; [email protected] and 2Norcape Observatory, PO Box 300, Exmouth, 6707, Australia; [email protected] Draft version March 30, 2021 ABSTRACT We present the results of 11 nights of CCD unfiltered photometry of V4743 Sgr (Nova Sgr 2002 # 3) from 2003 and 2005. We find two periods of 0.2799 d ≈ 6.7 h and 0.01642 d ≈ 24 min in the 2005 data. The long period is also present in the 2003 data, but only weak evidence of the shorter period is found in this year. The 24-min period is somewhat longer than the 22-min period, which was detected from X-ray observations. We suggest that the 6.7-h periodicity represents the orbital period of the underlying binary system and that the 24-min period is the beat periodicity between the orbital period and the X-ray period, which is presumably the spin period of the white dwarf. Thus, V4743 Sgr should be classified as an intermediate polar (DQ Her star). About six months after the nova outburst, the optical light curve of V4743 Sgr seemed to show quasi-periodic oscillations, which are typical of the transient phase in classical nova. Therefore, our results support the previous suggestion that the transition phase in novae may be related to intermediate polars. -
Combined Dynamical Effects of the Bar and Spiral Arms in a Galaxy Model
A&A 615, A10 (2018) Astronomy https://doi.org/10.1051/0004-6361/201833035 & c ESO 2018 Astrophysics Combined dynamical effects of the bar and spiral arms in a Galaxy model. Application to the solar neighbourhood T. A. Michtchenko, J. R. D. Lépine, D. A. Barros, and R. S. S. Vieira Universidade de São Paulo, IAG, Rua do Matão 1226, Cidade Universitária, 05508-090 São Paulo, Brazil e-mail: [email protected]; [email protected]; [email protected] Received 16 March 2018 / Accepted 17 April 2018 ABSTRACT Context. Observational data indicate that the Milky Way is a barred spiral galaxy. Computation facilities and availability of data from Galactic surveys stimulate the appearance of models of the Galactic structure, however further efforts are needed to build dynamical models containing both spiral arms and the central bar/bulge. Aims. We expand the study of the stellar dynamics in the Galaxy by adding the bar/bulge component to a model with spiral arms introduced in one of our previous publications. The model is tested by applying it to the solar neighbourhood, where observational data are more precise. Methods. We model analytically the potential of the Galaxy to derive the force field in its equatorial plane. The model comprises an axisymmetric disc derived from the observed rotation curve, four spiral arms with Gaussian-shaped groove profiles, and a classical elongated/oblate ellipsoidal bar/bulge structure. The parameters describing the bar/bulge are constrained by observations and the stel- lar dynamics, and their possible limits are determined. 9 Results. -
Observed Binaries with Compact Objects
Chapter 9 Observed binaries with compact objects This chapter provides an overview of observed types of binaries in which one or both stars are compact objects (white dwarfs, neutron stars or black holes). In many of these systems an important energy source is accretion onto the compact object. 9.1 Accretion power When mass falls on an object of mass M and with radius R, at a rate M˙ , a luminosity Lacc may be produced: GMM˙ L = (9.1) acc R The smaller the radius, the more energy can be released. For a white dwarf with M ≈ 0.7 M⊙ and −4 2 R ≈ 0.01 R⊙, this yields Lacc ≈ 1.5 × 10 Mc˙ . For a neutron star with M ≈ 1.4 M⊙ and R ≈ 10 km, we 2 2 2 find Lacc ≈ 0.2Mc˙ and for a black hole with Scwarzschild radius R ∼ 2GM/c we find Lacc ∼ 0.5Mc˙ , i.e. in the ideal case a sizable fraction of the rest mass may be released as energy. This accretion process is thus potentially much more efficient than nuclear fusion. However, the accretion luminosity should not be able to exceed the Eddington luminosity, 4πcGM L ≤ L = (9.2) acc Edd κ 2 where κ is the opacity, which may be taken as the electron scattering opacity, κes = 0.2(1 + X) cm /g for a hydrogen mass fraction X. Thus the compact accreting star may not be able to accrete more than a fraction of the mass that is transferred onto it by its companion. By equating Lacc to LEdd we obtain the maximum accretion rate, 4πcR M˙ = (9.3) Edd κ The remainder of the mass may be lost from the binary system, in the form of a wind or jets blown from the vicinity of the compact star, or it may accumulate in the accretor’s Roche lobe or in a common envelope around the system. -
Polars and Intermediate Polars
Polars and Intermediate Polars Christian Lerrahn <[email protected]> November 21, 2002 at IAAT T¨ubingen – Typeset by FoilTEX – Polars – Typeset by FoilTEX – 1 Overview - Polars • Polars – What is a Polar? – The Magnetic Field – Synchronous Rotation of the Primary – Lightcurves ∗ Spectra ∗ Emission – The Accretion – The Accretion Region – Problems with the Model – Typeset by FoilTEX – 2 What is a Polar? • subclass of the CVs • primary is a white dwarf with a strong magnetic field (typically 10-80 MG) • emission is strongly polarized at optical wavelength (both circularly and linearly) • no accretion disc • primary rotates synchronously • examples: AM Her, AR UMa, ST LMi, VV Pup – Typeset by FoilTEX – 3 The Magnetic Field • typical field strength of 10-80 MG • highest-field system: 230 MG (AR UMa) • probably dipole fields, possibly quadrupole fields Figure 1: The principle of cyclotron emission ∗ • Zeeman splitting, cyclotron harmonics, ratio of linear to circular polarization – Typeset by FoilTEX – 4 Synchronous Rotation • angular momentum of the accretion stream spins up the primary ⇒ short spin periods expected like those of non-magnetic CVs (≈ 50 s) • actual spin periods of 1-3 hrs!!! • fields will intertwine where they meet and entangle their field lines ⇒ drag force acting as a torque slowing down the primary ⇒ sychronization of the primary • still objects that rotate asynchronously – braking torque might be low (larger binary separation, weaker field) – asynchronism might be temporary (e.g. because of a nova like in V1500 Cyg) – Typeset by FoilTEX – 5 Lightcurves Figure 2: Optical lightcurve of an eclipsing system – Typeset by FoilTEX – 6 Emission Figure 3: Flux emitted from the accretion region – Typeset by FoilTEX – 7 Emission • cyclotron emission (CYC) (also see Fig.