A Guide for the Open Star Cluster Observing Club
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The Desert Sky Observer
Desert Sky Observer Volume 32 Antelope Valley Astronomy Club Newsletter February 2012 Up-Coming Events February 10: Club Meeting* February 11: Moon Walk @ Prime Desert Woodlands February 13: Executive Board Meeting @ Don’s house February 18: Telescope Night and Star Party @ Devil's Punchbowl * Monthly meetings are held at the S.A.G.E. Planetarium on the Cactus School campus in Palmdale, the second Friday of each month. The meeting location is at the northeast corner of Avenue R and 20th Street East. Meetings start at 7 p.m. and are open to the public. Please note that food and drink are not allowed in the planetarium President Don Bryden Well I gave a star party and no one showed up! Not that I can blame them – it was raining and windy and cold – it even hailed! Still I dragged out the scope and got it ready to go. Briefly, between the clouds I looked at Jupiter and it was quite a treat. The Galilean moons were all tight to the planet either coming from just in front or behind. It gave a bejeweled look like a large ruby surrounded by four small diamonds. Even with the winds and clouds the sky was surprisingly steady and I went as high as 260x with ease, exposing the shadow of Europa transiting the planet. But soon more clouds came and inside we had a nice fire so I put the Artist's rendering DVD “400 Years of the Telescope” on and settled in for the night. My daughter had a few friends over after a skating party that afternoon and later when I went out for one more look they came out to see what was up. -
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. -
CCD UBV Photometry and Kinematics of the Open Cluster NGC
CCD UBV Photometry and Kinematics of the Open Cluster NGC 225 Sel¸cuk Bilira,∗, Z. Funda Bostancıa, Talar Yontanb, Tolga G¨uvera, Volkan Bakı¸sc, Tansel Aka, Serap Aka, Ernst Paunzend, Zeki Ekerc aIstanbul University, Faculty of Science, Department of Astronomy and Space Sciences, 34119 University, Istanbul, Turkey bIstanbul University, Graduate School of Science and Engineering, Department of Astronomy and Space Sciences, 34116, Beyazıt, Istanbul, Turkey cDepartment of Space Sciences and Technologies, Faculty of Sciences, Akdeniz University, Antalya 07058, Turkey dDepartment of Theoretical Physics and Astrophysics, Masaryk University, Kotl´a˘rsk´a2, 611 37 Brno, Czech Republic Abstract We present the results of CCD UBV photometric and spectroscopic obser- vations of the open cluster NGC 225. In order to determine the structural parameters of NGC 225, we calculated the stellar density profile in the clus- ter’s field. We estimated the probabilities of the stars being physical members of the cluster using the existing astrometric data. The most likely members of the cluster were used in the determination of the astrophysical parame- ters of the cluster. We calculated the mean radial velocity of the cluster as −1 Vr = 8.3 5.0 km s from the optical spectra of eight stars in the cluster’s field.− Using± the U B vs B V two-colour diagram and UV excesses of the F- − − G type main-sequence stars, the reddening and metallicity of NGC 225 were inferred as E(B V )=0.151 0.047 mag and [Fe/H]= 0.11 0.01 dex, respectively. We− fitted the colour-magnitude± diagrams of NGC− 225± with the arXiv:1606.08608v1 [astro-ph.GA] 28 Jun 2016 PARSEC isochrones and derived the distance modulus, distance and age of the cluster as µ =9.3 0.07 mag, d = 585 20 pc and t = 900 100 Myr, V ± ± ± respectively. -
The Evolution of the Milky Way: New Insights from Open Clusters
Mon. Not. R. Astron. Soc. 000, 1–?? (2016) Printed 12 September 2016 (MN LATEX style file v2.2) The evolution of the Milky Way: New insights from open clusters Arumalla B. S. Reddy1⋆, David L. Lambert1 and Sunetra Giridhar2 1W.J. McDonald Observatory and Department of Astronomy, The University of Texas at Austin, Austin, TX 78712, USA 2Indian Institute of Astrophysics, Bangalore 560034, India Accepted 2016 September 07. Received 2016 September 07; in original form 2016 May 12 ABSTRACT We have collected high-dispersion echelle spectra of red giant members in the twelve open clusters (OCs) and derived stellar parameters and chemical abundances for 26 species by either line equivalent widths or synthetic spectrum analyses. We confirm the lack of an age−metallicity relation for OCs but argue that such a lack of trend for OCs arise from the limited coverage in metallicity compared to that of field stars which span a wide range in metallicity and age. We confirm that the radial metallicity gradient of OCs is steeper (flatter) for Rgc < 12 kpc (>12 kpc). We demonstrate that the sample of clusters constituting a steep radial metallicity −1 gradient of slope −0.052±0.011 dex kpc at Rgc < 12 kpc are younger than 1.5 Gyr and located close to the Galactic midplane (| z| < 0.5 kpc) with kinematics typical of the thin disc. Whereas the clusters describing a shallow slope of −0.015±0.007 −1 dex kpc at Rgc > 12 kpc are relatively old, thick disc members with a striking spread in age and height above the midplane (0.5 < | z| < 2.5 kpc). -
Mind the Gap, Part 2
Mind The Gap, Part 2 CFAS General Meeting Wednesday, September 10, 2014 Lacerta the Lizard As the last glow of evening twilight drains from the western sky during September evenings, the small constellation Lacerta crawls high overhead. This celestial lizard was created in 1687 by Johann Hevelius to fill the void between Cygnus and Andromeda. - Walter Scott Houston, Deep-Sky Wonders Urania’s Mirror, circa 1825 No region in the heavens is barren. No constellation is fruitless for the observer. Even a lifetime of exploring the celestial display cannot exhaust the surprises that dance so beautifully before the amateur astronomer. - WSHouston NGC 7243 (Caldwell 16), is an open cluster of magnitude +6.4. It is located near the naked-eye stars Alpha Lacertae, 4 Lacertae, an A-class double star, and planetary nebula IC 5217. It lies approximately 2,800 light-years away, and is thought to be just over 100 million years old, consisting mainly of white and blue stars. NGC 7209 is a young, open cluster estimated to be around 410 million years-old and as suggested by the plethora of bright bluish stars. It is comprised of approximately 100 member stars and dominated by a handful of magnitude 7 to 9 stars and which includes an impressive pair of carbon stars at its center (mags 9.48 and 10.11). NGC 7209 is well-detached from the backround sky with a slight vertical concentration in a field spanning the apparent diameter of the full moon. The cluster has been estimated to lie at a distance of 3,810 light-years away. -
A Spitzer Study of Debris Disks in the Young Nearby Cluster NGC 2232
A Spitzer Study of Debris Disks In The Young Nearby Cluster NGC 2232: Icy Planets Are Common Around ∼ 1.5–3 M⊙ Stars Thayne Currie1, Peter Plavchan2, and Scott J. Kenyon1 [email protected], [email protected], [email protected] ABSTRACT We describe Spitzer IRAC and MIPS observations of the nearby 25 Myr- old open cluster NGC 2232. Combining these data with ROSAT All-Sky Survey observations, proper motions, and optical photometry/spectroscopy, we construct a list of highly probable cluster members. We identify 1 A-type star, HD 45435, with definite excess emission at 4.5–24 µm indicative of debris from terrestrial planet formation. We also identify 2–4 late-type stars with possible 8 µm excesses, and 8 early-type stars with definite 24 µm excesses. Constraints on the dust luminosity and temperature suggest that the detected excesses are produced by debris disks. From our sample of B and A stars, stellar rotation appears correlated with 24 µm excess, a result expected if massive primordial disks evolve into massive debris disks. To explore the evolution of the frequency and magnitude of debris around A-type stars, we combine our results with data for other young clusters. The frequency of debris disks around A-type stars appears to increase from ∼ 25% at 5 Myr to ∼ 50–60% at 20–25 Myr. Older A-type stars have smaller debris disk frequencies: ∼ 20% at 50–100 Myr. For these ages, the typical level of debris emission rises from 5–20 Myr and then declines. Because 24 µm dust emission probes icy planet formation around A-type stars, our results suggest that the frequency of icy planet formation is ηi & 0.5–0.6. -
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). -
Download This Article in PDF Format
A&A 453, 101–119 (2006) Astronomy DOI: 10.1051/0004-6361:20053894 & c ESO 2006 Astrophysics On the difference between nuclear and contraction ages, W. Lyra1,2,3,A.Moitinho4,N.S.vanderBliek1,andJ.Alves5 1 Cerro Tololo Interamerican Observatory, Casilla 603 La Serena, Chile 2 Observatório do Valongo/UFRJ, Ladeira do Pedro Antônio 43, 20080-090 Rio de Janeiro, Brazil 3 Department of Astronomy and Space Physics, Uppsala Astronomical Observatory, Box 515, 751 20 Uppsala, Sweden e-mail: [email protected] 4 Observatório Astronómico de Lisboa, Tapada da Ajuda, 1349-018 Lisbon, Portugal 5 European Southern Observatory, Karl-Schwarzschild 2, 85748 Garching, Germany Received 23 July 2005 / Accepted 20 February 2006 ABSTRACT Context. Ages derived from low mass stars still contracting onto the main sequence often differ from ages derived from the high mass ones that have already evolved away from it. Aims. We investigate the general claim of disagreement between these two independent age determinations by presenting UBVRI pho- tometry for the young galactic open clusters NGC 2232, NGC 2516, NGC 2547 and NGC 4755, spanning the age range ∼10–150 Myr Methods. We derived reddenings, distances, and nuclear ages by fitting ZAMS and isochrones to color–magnitudes and color–color di- agrams. To derive contraction ages, we used four different pre-main sequence models, with an empirically calibrated color-temperature relation to match the Pleiades cluster sequence. Results. When exclusively using the V vs. V − I color–magnitude diagram and empirically calibrated isochrones, there is consistency between nuclear and contraction ages for the studied clusters. -
September 2020 BRAS Newsletter
A Neowise Comet 2020, photo by Ralf Rohner of Skypointer Photography Monthly Meeting September 14th at 7:00 PM, via Jitsi (Monthly meetings are on 2nd Mondays at Highland Road Park Observatory, temporarily during quarantine at meet.jit.si/BRASMeets). GUEST SPEAKER: NASA Michoud Assembly Facility Director, Robert Champion What's In This Issue? President’s Message Secretary's Summary Business Meeting Minutes Outreach Report Asteroid and Comet News Light Pollution Committee Report Globe at Night Member’s Corner –My Quest For A Dark Place, by Chris Carlton Astro-Photos by BRAS Members Messages from the HRPO REMOTE DISCUSSION Solar Viewing Plus Night Mercurian Elongation Spooky Sensation Great Martian Opposition Observing Notes: Aquila – The Eagle Like this newsletter? See PAST ISSUES online back to 2009 Visit us on Facebook – Baton Rouge Astronomical Society Baton Rouge Astronomical Society Newsletter, Night Visions Page 2 of 27 September 2020 President’s Message Welcome to September. You may have noticed that this newsletter is showing up a little bit later than usual, and it’s for good reason: release of the newsletter will now happen after the monthly business meeting so that we can have a chance to keep everybody up to date on the latest information. Sometimes, this will mean the newsletter shows up a couple of days late. But, the upshot is that you’ll now be able to see what we discussed at the recent business meeting and have time to digest it before our general meeting in case you want to give some feedback. Now that we’re on the new format, business meetings (and the oft neglected Light Pollution Committee Meeting), are going to start being open to all members of the club again by simply joining up in the respective chat rooms the Wednesday before the first Monday of the month—which I encourage people to do, especially if you have some ideas you want to see the club put into action. -
The List of Possible Double and Multiple Open Clusters Between Galactic Longitudes 240O and 270O
The list of possible double and multiple open clusters between galactic longitudes 240o and 270o Juan Casado Facultad de Ciencias, Universidad Autónoma de Barcelona, 08193, Bellaterra, Catalonia, Spain Email: [email protected] Abstract This work studies the candidate double and multiple open clusters (OCs) in the galactic sector from l = 240o to l = 270o, which contains the Vela-Puppis star formation region. To do that, we have searched the most recent and complete catalogues of OCs by hand to get an extensive list of 22 groups of OCs involving 80 candidate members. Gaia EDR3 has been used to review some of the candidate OCs and look for new OCs near the candidate groups. Gaia data also permitted filtering out most of the field sources that are not member stars of the OCs. The plotting of combined colour-magnitude diagrams of candidate pairs has allowed, in several cases, endorsing or discarding their link. The most likely systems are formed by OCs less than 0.1 Gyr old, with only one eccentric OC in this respect. No probable system of older OCs has been found. Preliminary estimations of the fraction of known OCs that form part of groups (9.4 to 15%) support the hypothesis that the Galaxy and the Large Magellanic Cloud are similar in this respect. The results indicate that OCs are born in groups like stars are born in OCs. Keywords Binary open clusters; Open cluster groups; Open cluster formation; Gaia; Manual search; Large Magellanic Cloud. 1. Introduction Open clusters are formed in giant molecular clouds and there is observational evidence suggesting that they can form in groups (Camargo et al. -
197 6Apjs. . .30. .451H the Astrophysical Journal Supplement Series, 30:451-490, 1976 April © 1976. the American Astronomical S
.451H The Astrophysical Journal Supplement Series, 30:451-490, 1976 April .30. © 1976. The American Astronomical Society. All rights reserved. Printed in U.S.A. 6ApJS. 197 EVOLVED STARS IN OPEN CLUSTERS Gretchen L. H. Harris* David Dunlap Observatory, Richmond Hill, Ontario Received 1974 September 16; revised 1975 June 18 ABSTRACT Radial-velocity observations and MK classifications have been used to study evolved stars in 25 open clusters. Published data on stars in 72 additional clusters are rediscussed and com- bined with the observations friade in this investigation to yield positions in the Hertzsprung- Russell diagram for 559 evolved stars in 97 clusters. Ages for the parent clusters were estimated from the main-sequence turnoff points, earliest spectral types, and bluest stars in the clusters themselves. The evolved stars were sorted into six age groups ranging from 4 x 106 yr to 4 x 108 yr, and the composite H-R diagram for each age group was then used to study the evolutionary tracks for stars of various masses. The observational results were found to be in reasonably good agreement with recent theoretical computations. The composite color-magnitude diagrams were found to be strikingly different from those of the rich open clusters in the Magellanic Clouds. At a given age the red giants in the Small Magellanic Cloud and the Large Magellanic Cloud clusters are brighter and bluer than their galactic counterparts. It is suggested that these effects may be accounted for by differences in metal abundance. Subject headings: clusters: open — galaxies: Magellanic Clouds — radial velocities — stars : evolution — stars : late-type — stars : spectral classification 1.