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A&A 454, 527–536 (2006) Astronomy DOI: 10.1051/0004-6361:20053468 & c ESO 2006 Astrophysics A search for photometric variability of hydrogen-deficient planetary-nebula nuclei, J. M. González Pérez1,2, J.-E. Solheim2,3, and R. Kamben2 1 Instituto de Astrofísica de Canarias, 38200 La Laguna, Tenerife, Spain e-mail: [email protected] 2 Institut of Physics, University of Tromsø, 9037 Tromsø, Norway 3 Institut of Theoretical Astrophysics, University of Oslo, PO box 1029 Blindern, 0315 Oslo, Norway Received 18 May 2005 / Accepted 9 March 2006 ABSTRACT Aims. We searched for photometric variability in a sample of hot, hydrogen-deficient planetary nebula nuclei (PNNi) with “PG 1159” or “O VI” spectral type, most of them embedded in a bipolar or elliptical planetary nebula envelope (PNe). These characteristics may indicate the presence of a hidden close companion and an evolution affected by episodes of interaction between them. Methods. We obtained time-series photometry from a sample of 11 candidates using the Nordic Optical Telescope (NOT) with the Andalucía Faint Object Spectrograph and Camera (ALFOSC), modified with our own control software to be able to observe in a high- speed multi-windowing mode. The data were reduced on-line with the real time photometry (RTP) code, which allowed us to detect periodic variable stars with small amplitudes from CCD data in real time. We studied the properties of the observed modulation fre- quencies to investigate their nature. Results. We report the first detection of low-amplitude pulsations in the PNNi VV 47, NGC 6852, and Jn 1. In addition, we investi- gated the photometric variability of NGC 246. -
Winter Constellations
Winter Constellations *Orion *Canis Major *Monoceros *Canis Minor *Gemini *Auriga *Taurus *Eradinus *Lepus *Monoceros *Cancer *Lynx *Ursa Major *Ursa Minor *Draco *Camelopardalis *Cassiopeia *Cepheus *Andromeda *Perseus *Lacerta *Pegasus *Triangulum *Aries *Pisces *Cetus *Leo (rising) *Hydra (rising) *Canes Venatici (rising) Orion--Myth: Orion, the great hunter. In one myth, Orion boasted he would kill all the wild animals on the earth. But, the earth goddess Gaia, who was the protector of all animals, produced a gigantic scorpion, whose body was so heavily encased that Orion was unable to pierce through the armour, and was himself stung to death. His companion Artemis was greatly saddened and arranged for Orion to be immortalised among the stars. Scorpius, the scorpion, was placed on the opposite side of the sky so that Orion would never be hurt by it again. To this day, Orion is never seen in the sky at the same time as Scorpius. DSO’s ● ***M42 “Orion Nebula” (Neb) with Trapezium A stellar nursery where new stars are being born, perhaps a thousand stars. These are immense clouds of interstellar gas and dust collapse inward to form stars, mainly of ionized hydrogen which gives off the red glow so dominant, and also ionized greenish oxygen gas. The youngest stars may be less than 300,000 years old, even as young as 10,000 years old (compared to the Sun, 4.6 billion years old). 1300 ly. 1 ● *M43--(Neb) “De Marin’s Nebula” The star-forming “comma-shaped” region connected to the Orion Nebula. ● *M78--(Neb) Hard to see. A star-forming region connected to the Orion Nebula. -
Planetary Nebulae
Planetary Nebulae A planetary nebula is a kind of emission nebula consisting of an expanding, glowing shell of ionized gas ejected from old red giant stars late in their lives. The term "planetary nebula" is a misnomer that originated in the 1780s with astronomer William Herschel because when viewed through his telescope, these objects appeared to him to resemble the rounded shapes of planets. Herschel's name for these objects was popularly adopted and has not been changed. They are a relatively short-lived phenomenon, lasting a few tens of thousands of years, compared to a typical stellar lifetime of several billion years. The mechanism for formation of most planetary nebulae is thought to be the following: at the end of the star's life, during the red giant phase, the outer layers of the star are expelled by strong stellar winds. Eventually, after most of the red giant's atmosphere is dissipated, the exposed hot, luminous core emits ultraviolet radiation to ionize the ejected outer layers of the star. Absorbed ultraviolet light energizes the shell of nebulous gas around the central star, appearing as a bright colored planetary nebula at several discrete visible wavelengths. Planetary nebulae may play a crucial role in the chemical evolution of the Milky Way, returning material to the interstellar medium from stars where elements, the products of nucleosynthesis (such as carbon, nitrogen, oxygen and neon), have been created. Planetary nebulae are also observed in more distant galaxies, yielding useful information about their chemical abundances. In recent years, Hubble Space Telescope images have revealed many planetary nebulae to have extremely complex and varied morphologies. -
How to Make $1000 with Your Telescope! – 4 Stargazers' Diary
Fort Worth Astronomical Society (Est. 1949) February 2010 : Astronomical League Member Club Calendar – 2 Opportunities & The Sky this Month – 3 How to Make $1000 with your Telescope! – 4 Astronaut Sally Ride to speak at UTA – 4 Aurgia the Charioteer – 5 Stargazers’ Diary – 6 Bode’s Galaxy by Steve Tuttle 1 February 2010 Sunday Monday Tuesday Wednesday Thursday Friday Saturday 1 2 3 4 5 6 Algol at Minima Last Qtr Moon Æ 5:48 am 11:07 pm Top ten binocular deep-sky objects for February: M35, M41, M46, M47, M50, M93, NGC 2244, NGC 2264, NGC 2301, NGC 2360 Top ten deep-sky objects for February: M35, M41, M46, M47, M50, M93, NGC 2261, NGC 2362, NGC 2392, NGC 2403 7 8 9 10 11 12 13 Algol at Minima Morning sports a Moon at Apogee New Moon Æ super thin crescent (252,612 miles) 8:51 am 7:56 pm Moon 8:00 pm 3RF Star Party Make use of the New Moon Weekend for . better viewing at the Dark Sky Site See Notes Below New Moon New Moon Weekend Weekend 14 15 16 17 18 19 20 Presidents Day 3RF Star Party Valentine’s Day FWAS Traveler’s Guide Meeting to the Planets UTA’s Maverick Clyde Tombaugh Ranger 8 returns Normal Room premiers on Speakers Series discovered Pluto photographs and NatGeo 7pm Sally Ride “Fat Tuesday” Ash Wednesday 80 years ago. impacts Moon. 21 22 23 24 25 26 27 Algol at Minima First Qtr Moon Moon at Perigee Å (222,345 miles) 6:42 pm 12:52 am 4 pm {Low in the NW) Algol at Minima Æ 9:43 pm Challenge binary star for month: 15 Lyncis (Lynx) Challenge deep-sky object for month: IC 443 (Gemini) Notable carbon star for month: BL Orionis (Orion) 28 Notes: Full Moon Look for a very thin waning crescent moon perched just above and slightly right of tiny Mercury on the morning of 10:38 pm Feb. -
Feb BACK BAY 2019
Feb BACK BAY 2019 The official newsletter of the Back Bay Amateur Astronomers CONTENTS COMING UP Gamma Burst 2 Feb 7 BBAA Meeting Eclipse Collage 3 7:30-9PM TCC, Virginia Beach NSN Article 6 Heart Nebula 7 Feb 8 Silent Sky Club meeting 10 10-11PM Little Theatre of VB Winter DSOs 11 Contact info 16 Feb 8 Cornwatch Photo by Chuck Jagow Canon 60Da, various exposures, iOptron mount with an Orion 80ED Calendar 17 dusk-dawn The best 9 out of 3465 images taken from about 10:00 PM on the 20th Cornland Park through 2:20 AM on the 21st. Unprocessed images (only cropped). Feb 14 Garden Stars 7-8:30PM LOOKING UP! a message from the president Norfolk Botanical Gardens This month’s most talked about astronomy event has to be the total lunar Feb 16 Saturday Sun-day eclipse. The BBAA participated by supporting the Watch Party at the 10AM-1PM Chesapeake Planetarium. Anyone in attendance will tell you it was COLD, but Elizabeth River Park manageable if you wore layers, utilized the planetarium where Dr. Robert Hitt seemed to have the thermostat set to 100 degrees, and drank copious amounts Feb 23 Skywatch of the hot coffee that Kent Blackwell brewed in the back office. 6PM-10PM The event had a huge following on Facebook but with the cold Northwest River Park temperatures, we weren’t sure how many would come out. By Kent’s estimate there were between 100–200 people in attendance. Many club members set up telescopes, as well as a few members of the public too. -
Ghost Hunt Challenge 2020
Virtual Ghost Hunt Challenge 10/21 /2020 (Sorry we can meet in person this year or give out awards but try doing this challenge on your own.) Participant’s Name _________________________ Categories for the competition: Manual Telescope Electronically Aided Telescope Binocular Astrophotography (best photo) (if you expect to compete in more than one category please fill-out a sheet for each) ** There are four objects on this list that may be beyond the reach of beginning astronomers or basic telescopes. Therefore, we have marked these objects with an * and provided alternate replacements for you just below the designated entry. We will use the primary objects to break a tie if that’s needed. Page 1 TAS Ghost Hunt Challenge - Page 2 Time # Designation Type Con. RA Dec. Mag. Size Common Name Observed Facing West – 7:30 8:30 p.m. 1 M17 EN Sgr 18h21’ -16˚11’ 6.0 40’x30’ Omega Nebula 2 M16 EN Ser 18h19’ -13˚47 6.0 17’ by 14’ Ghost Puppet Nebula 3 M10 GC Oph 16h58’ -04˚08’ 6.6 20’ 4 M12 GC Oph 16h48’ -01˚59’ 6.7 16’ 5 M51 Gal CVn 13h30’ 47h05’’ 8.0 13.8’x11.8’ Whirlpool Facing West - 8:30 – 9:00 p.m. 6 M101 GAL UMa 14h03’ 54˚15’ 7.9 24x22.9’ 7 NGC 6572 PN Oph 18h12’ 06˚51’ 7.3 16”x13” Emerald Eye 8 NGC 6426 GC Oph 17h46’ 03˚10’ 11.0 4.2’ 9 NGC 6633 OC Oph 18h28’ 06˚31’ 4.6 20’ Tweedledum 10 IC 4756 OC Ser 18h40’ 05˚28” 4.6 39’ Tweedledee 11 M26 OC Sct 18h46’ -09˚22’ 8.0 7.0’ 12 NGC 6712 GC Sct 18h54’ -08˚41’ 8.1 9.8’ 13 M13 GC Her 16h42’ 36˚25’ 5.8 20’ Great Hercules Cluster 14 NGC 6709 OC Aql 18h52’ 10˚21’ 6.7 14’ Flying Unicorn 15 M71 GC Sge 19h55’ 18˚50’ 8.2 7’ 16 M27 PN Vul 20h00’ 22˚43’ 7.3 8’x6’ Dumbbell Nebula 17 M56 GC Lyr 19h17’ 30˚13 8.3 9’ 18 M57 PN Lyr 18h54’ 33˚03’ 8.8 1.4’x1.1’ Ring Nebula 19 M92 GC Her 17h18’ 43˚07’ 6.44 14’ 20 M72 GC Aqr 20h54’ -12˚32’ 9.2 6’ Facing West - 9 – 10 p.m. -
A Gaia DR2 View of the Open Cluster Population in the Milky Way T
Astronomy & Astrophysics manuscript no. manuscript˙arXiv2 © ESO 2018 July 13, 2018 A Gaia DR2 view of the Open Cluster population in the Milky Way T. Cantat-Gaudin1, C. Jordi1, A. Vallenari2, A. Bragaglia3, L. Balaguer-Nu´nez˜ 1, C. Soubiran4, D. Bossini2, A. Moitinho5, A. Castro-Ginard1, A. Krone-Martins5, L. Casamiquela4, R. Sordo2, and R. Carrera2 1 Institut de Ciencies` del Cosmos, Universitat de Barcelona (IEEC-UB), Mart´ı i Franques` 1, E-08028 Barcelona, Spain 2 INAF-Osservatorio Astronomico di Padova, vicolo Osservatorio 5, 35122 Padova, Italy 3 INAF-Osservatorio di Astrofisica e Scienza dello Spazio, via Gobetti 93/3, 40129 Bologna, Italy 4 Laboratoire dAstrophysique de Bordeaux, Univ. Bordeaux, CNRS, UMR 5804, 33615 Pessac, France 5 CENTRA, Faculdade de Ciencias,ˆ Universidade de Lisboa, Ed. C8, Campo Grande, P-1749-016 Lisboa, Portugal Received date / Accepted date ABSTRACT Context. Open clusters are convenient probes of the structure and history of the Galactic disk. They are also fundamental to stellar evolution studies. The second Gaia data release contains precise astrometry at the sub-milliarcsecond level and homogeneous pho- tometry at the mmag level, that can be used to characterise a large number of clusters over the entire sky. Aims. In this study we aim to establish a list of members and derive mean parameters, in particular distances, for as many clusters as possible, making use of Gaia data alone. Methods. We compile a list of thousands of known or putative clusters from the literature. We then apply an unsupervised membership assignment code, UPMASK, to the Gaia DR2 data contained within the fields of those clusters. -
February 14, 2015 7:00Pm at the Herrett Center for Arts & Science Colleagues, College of Southern Idaho
Snake River Skies The Newsletter of the Magic Valley Astronomical Society www.mvastro.org Membership Meeting President’s Message Saturday, February 14, 2015 7:00pm at the Herrett Center for Arts & Science Colleagues, College of Southern Idaho. Public Star Party Follows at the It’s that time of year when obstacles appear in the sky. In particular, this year is Centennial Obs. loaded with fog. It got in the way of letting us see the dance of the Jovian moons late last month, and it’s hindered our views of other unique shows. Still, members Club Officers reported finding enough of a clear sky to let us see Comet Lovejoy, and some great photos by members are popping up on the Facebook page. Robert Mayer, President This month, however, is a great opportunity to see the benefit of something [email protected] getting in the way. Our own Chris Anderson of the Herrett Center has been using 208-312-1203 the Centennial Observatory’s scope to do work on occultation’s, particularly with asteroids. This month’s MVAS meeting on Feb. 14th will give him the stage to Terry Wofford, Vice President show us just how this all works. [email protected] The following weekend may also be the time the weather allows us to resume 208-308-1821 MVAS-only star parties. Feb. 21 is a great window for a possible star party; we’ll announce the location if the weather permits. However, if we don’t get that Gary Leavitt, Secretary window, we’ll fall back on what has become a MVAS tradition: Planetarium night [email protected] at the Herrett Center. -
A Basic Requirement for Studying the Heavens Is Determining Where In
Abasic requirement for studying the heavens is determining where in the sky things are. To specify sky positions, astronomers have developed several coordinate systems. Each uses a coordinate grid projected on to the celestial sphere, in analogy to the geographic coordinate system used on the surface of the Earth. The coordinate systems differ only in their choice of the fundamental plane, which divides the sky into two equal hemispheres along a great circle (the fundamental plane of the geographic system is the Earth's equator) . Each coordinate system is named for its choice of fundamental plane. The equatorial coordinate system is probably the most widely used celestial coordinate system. It is also the one most closely related to the geographic coordinate system, because they use the same fun damental plane and the same poles. The projection of the Earth's equator onto the celestial sphere is called the celestial equator. Similarly, projecting the geographic poles on to the celest ial sphere defines the north and south celestial poles. However, there is an important difference between the equatorial and geographic coordinate systems: the geographic system is fixed to the Earth; it rotates as the Earth does . The equatorial system is fixed to the stars, so it appears to rotate across the sky with the stars, but of course it's really the Earth rotating under the fixed sky. The latitudinal (latitude-like) angle of the equatorial system is called declination (Dec for short) . It measures the angle of an object above or below the celestial equator. The longitud inal angle is called the right ascension (RA for short). -
August 2012 of You Know I Went to the Astronomical League Conference (Alcon) in Chicago at the Beginning of July with My Grandmother
BACKBACK BAYBAY observerobserver The Official Newsletter of the Back Bay Amateur Astronomers P.O. Box 9877, Virginia Beach, VA 23450-9877 Looking Up! Hello again! This month I actually have a story EPHEMERALS to tell, instead of just random ramblings. As most august 2012 of you know I went to the Astronomical League Conference (ALCon) in Chicago at the beginning of July with my grandmother. It was great. Not quite 08/24, 7:00 pm as good as last year, seeing as I had to pay for it Night Hike and they didn’t give me a check and a plaque this Northwest River Park year (last year I won the Horkheimer Youth award, which paid for my trip), but it was still a lot of fun, and very educational. I met a lot of cool 08/24, 8:00 pm people and definitely learned something. The Garden Stars whole trip was a big story, but a few events stand Norfolk Botanical Gardens out the most in my memory, and they’re all connected to some extent. 08/28, 7:00 pm Boardwalk Astronomy It all started on the day we got there. ALCon is Near 24th St Stage an annual four day conference usually in the VA Beach Oceanfront beginning of July. This year, the day we got there was July fourth. After checking in, taking a nap and 09/06, 7:30 pm dining, we decided to participate in the observing BBAA Monthly Meeting event outside the hotel. It was in a parking lot with lights, and fireworks, but there was a large moon TCC Campus and Saturn was up, so we went for it. -
Understanding the H2/HI Ratio in Galaxies 3
Mon. Not. R. Astron. Soc. 394, 1857–1874 (2009) Printed 6 August 2021 (MN LATEX style file v2.2) Understanding the H2/HI Ratio in Galaxies D. Obreschkow and S. Rawlings Astrophysics, Department of Physics, University of Oxford, Keble Road, Oxford, OX1 3RH, UK Accepted 2009 January 12 ABSTRACT galaxy We revisit the mass ratio Rmol between molecular hydrogen (H2) and atomic hydrogen (HI) in different galaxies from a phenomenological and theoretical viewpoint. First, the local H2- mass function (MF) is estimated from the local CO-luminosity function (LF) of the FCRAO Extragalactic CO-Survey, adopting a variable CO-to-H2 conversion fitted to nearby observa- 5 1 tions. This implies an average H2-density ΩH2 = (6.9 2.7) 10− h− and ΩH2 /ΩHI = 0.26 0.11 ± · galaxy ± in the local Universe. Second, we investigate the correlations between Rmol and global galaxy properties in a sample of 245 local galaxies. Based on these correlations we intro- galaxy duce four phenomenological models for Rmol , which we apply to estimate H2-masses for galaxy each HI-galaxy in the HIPASS catalog. The resulting H2-MFs (one for each model for Rmol ) are compared to the reference H2-MF derived from the CO-LF, thus allowing us to determine the Bayesian evidence of each model and to identify a clear best model, in which, for spi- galaxy ral galaxies, Rmol negatively correlates with both galaxy Hubble type and total gas mass. galaxy Third, we derive a theoretical model for Rmol for regular galaxies based on an expression for their axially symmetric pressure profile dictating the degree of molecularization. -
Planetary Nebulae: Exposing the Top Polluters of the ISM
The Evolving ISM in the Milky Way & Nearby Galaxies Planetary Nebulae: Exposing the Top Polluters of the ISM Joseph L. Hora1, Massimo Marengo1, Howard A. Smith1, Luciano Cerrigone1, William B. Latter2 ABSTRACT The high mass loss rates of stars in their asymptotic giant branch (AGB) stage of evolution is one of the most important pathways for mass return from stars to the ISM. In the planetary nebulae (PNe) phase, the ejected material is illuminated and can be altered by the UV radiation from the central star. PNe therefore play a significant role in the ISM recycling process and in changing the environment around them. We show some highlights of the results of observations that have been carried out using the Spitzer instruments to study the gas and dust emission from PNe in the Milky Way and nearby galaxies. Spitzer is especially sensitive to the cool dust and molecules in the PNe shell and halos. We present new results from our program on Galactic PNe, including IRAC and IRS observations of NGC 6720 in the ring and halo of that nebula. Subject headings: galaxies: ISM | infrared: galaxies | infrared: ISM | ISM: dust, extinction | ISM: structure 1. Introduction A key link in the recycling of material to the Interstellar Medium (ISM) is the phase of stellar evolution from Asymptotic Giant Branch (AGB) to white dwarf star. When stars are on the AGB, they begin to lose mass at a prodigious rate. The stars on the AGB are relatively cool, and their atmospheres are a fertile environment for the formation of dust and molecules.