DOCSLIB.ORG

September 2020 by Jamie Canfield, Secretary

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text

Load more

PRESIDENT’S NOTES MONTHLY MEETING By Terry Phillips Shelter in Place Remote General Assembly Meeting ast month we had an in-depth panel discussion with Astronomy Technology Today’s Stuart Parkerson and Explore Scientific’s Scott LRoberts about the state of the amateur astronomy business and the impact on it of the Covid-19 pandemic. Both agreed that the sector has seen a pretty good bump up as many people turned to astronomy as a Friday, Nov. 13, 2020 hobby that can help maintain one’s sanity in a locked down world. The importance of astronomy outreach was particularly emphasized, and I 7:30 PM was truly amazed at the amount of online astronomy content Scott is producing. He is literally streaming daily features at Explore Alliance Live and his YouTube channel is feeding into four main forums: Explore Now, You should have received a Global Star Party, OpenGOTO, and How To. In the past few months Scott has hosted over 20 Global Star Parties and OpenGOTO forum has put out link via email to join the ZOOM over 100 informative videos. He is frequently bringing in some of the big virtual meeting. names in the astronomy community to present. Head over to https:// explorescientificusa.com/pages/explore-alliance-live to find out more If you have not received the Zoom meeting email, about tapping into this rich fount of astronomical knowledge and exper- contact [email protected] for access tise. information prior to the meeting or The work that Scott and others are doing is making me feel like AAS is call Dawn (512-663-2249) or Tim (512-577-8340) at the start of the meeting for help connecting. taking really baby steps into the online media outreach pond. So, we’ve had to learn a lot about Zoom and YouTube the past few months. I finally managed to get setup to simulcast our Zoom GA meetings to our pre- viously existing but mostly dormant AustinAstro YouTube channel. And this week I finished downloading all our past Zoom meetings sand up- loaded them to the YouTube channel. You can review our past meetings by going to https://youtube.com and searching for AustinAstro. If you want access to maintain content on the YouTube channel contact Sean Leary ([email protected]). I sent an email blast to the membership this week to let everybody know Sidereal Times Vol. 52 Issue 11 Banner: Oct. 2020 Image of the Month: Trew Hoffman, North America Nebula in SHO http://www.austinastro.org/ Sidereal Times is the official monthly publication of the Austin Astronomical Sidereal Times • November 2020 • 1 Society. President’s Notes Continued 1-2 Presidents Notes November Guest Speaker that we have completed a deal with Stuart Parkerson to allow our members to read Astronomy Technology Today online at no cost. This is a terrific source of information about astronomy related gear. Let us know at [email protected] if you missed the instructions on how to set this up. 4 On the Horizon AAS VP Report In the same email I let everybody know that we received an invitation for members to join a series of Online Viewing Sessions being produced the astronomy society in Kalamazoo Michigan (KAS). They have a nice automated observatory located in Arizona Sky Village near Portal AZ. They are at 4,500 ft with Bortle 2 skies. 5 The ALCORNER The featured instrument is a quartz 20” Plane Wave CDK with a TAK FSQ-106ED refractor riding shotgun. They are hosting monthly sessions. You have to register for each session, but it is easily done at https://www. kasonline.org/viewing.html . The meetings are hosted on Zoom and simulcast to YouTube. I am looking 6 Outreach Report forward to seeing how KAS implements online star parties. & Calendar of Events Tim Brown sent an all members email this week discussing and seeking input on how best to conduct small, covid safe star parties at Bad Wolf Ranch. Many members feel that it is safe if proper precautions are taken. Please let Tim, know your thoughts about this, and if a consensus can be reached, we may try to hold a party 7 The International Space Station in December. I’ve been watching the major planets continue to put on a good show in the evening hours. In recent days 8-9 Bad Wolf Ranch I’ve been out walking after sunset and I’ve finally been able to detect a nightly closure as Jupiter is about to lap Saturn. In about six weeks the two will close to only 10 arcminutes. They will still be distinguishable as two bodies barely, but if you put a telescope on them, you’ll be in for a real treat. They will be low in the west 10-12 Pedernales Report November 2020 just after sunset, so go scout yourself a viewing spot with a nice clear southwestern horizon. You won’t want to miss this. 13-14 Observing Targets November 2020 Terry November Meeting Guest Speaker: Byron Miller Topic: “Backyard Astrophotography - Deep Space Imaging for Amateur Astronomers.” Club webmaster Byron Miller’s presentation will be on “Backyard Astrophotography - Deep Space Imaging for Amateur Astrono- mers.” From proper polar alignment to dealing with light pollution, we’ll explore the ways in which you can enjoy the cosmos and explore the universe through Astrophotography from the comfort of your own backyard. 2 •November 2020 • Sidereal Times INSIDE THIS ISSUE 1-2 Presidents Notes November Guest Speaker 15-16 The Discoveries of Galileo – Part 4: Venus 4 On the Horizon AAS VP Report 17-19 Image Of The Month & Members Image Gallery 5 The ALCORNER 20 Treasurer’s Report 6 Outreach Report & Calendar of Events 21-23 GA and EC Minutes 7 The International Space Station 24 Membership Cards 8-9 Bad Wolf Ranch 25 Joining AAS 10-12 Pedernales Report November 2020 26 2020-2021 Officers List -vacant positions 13-14 Observing Targets November 2020 AAS AFFILIATIONS http://darksky.org/ https://nightsky.jpl.nasa.gov https://www.astroleague.org/ http://www.tsgc.utexas.edu/ Sidereal Times • November 2020 • 3 ON THE HORIZON: GENERAL ASSEMBLY MEETINGS BY MICHAEL E. MAROTTA, VICE PRESIDENT December 11 Traditional Austin Astronomical Society Holiday Party. As close as virtually possible to a social gathering. Any and all attending members are invited to bring their 2-minute video or slide presen- tation to share with us. After the (short) business meeting, we will set up into Zoom “chat rooms” for small groups. At the end of the night, we will announce the winner of the “Image of the Year” award. Contestants are the 12 “Image of the Month” winners. Members will have voted via the AAS website. January 8, 2021 “Spectroscopy” by Tom Field, inventor of spectroscopy tools for educators and hobbyists. It is now possible for amateur astronomers to image, record, and analyze the spectra of our targets. Spectroscopy reveals chemical sig- natures, red shifts, and blue shifts. Modern equipment screws into your telescope eyepiece or camera objective. Computer software supports your analysis of your images. February 12, 2021 Young Stars in Our Neighborhood by Ronan M. Kerr, University of Texas. The Sco-Cen (Scorpius-Centaurus) association consists of spectral classes O and B. Kerr’s research is identi- fying some new young stellar groups first the time. His presentation will explain the star formation history and structure found in Sco-Cen, and reveal the larger-scale architecture of star formation in our stellar neighborhood. March 12, 2021: To be Announced. April 9, 2021: The Heaven Watcher’s Observatory with Rev. Jason Fry and Rob Teeter of Teeter’s Telescopes (https://www.teeterstelescopes.com) maker of custom-built (“be- spoke”) instruments such the one shown here with Jason Fry who views the sky from his “Cielo Vista Observatory” seven miles south of Alpine, between Fort Davis and Big Bend. Upcoming: Dr. Mariba Jah, University of Texas, on non-gravitational orbit plotting. Redshift—The October 2020 Meeting with Scott Roberts of Explore Scientific and Stuart Parkerson of Astronomical Technology Today. Archived on YouTube here: https://www.youtube.com/watch?v=Ubx- qbMS4-vY (or Search for Austin Astronomical Society.) Redshift—Kurt Baty’s September 11 presentation, “The Antikythera Device,” could not be livestreamed to YouTube because it included copyrighted material from PBS Nova and other sources. However, you can view a short presentation by Kurt for “Brick Fiesta 2017” a Lego convention on “Beyond the Brick” on You- Tube here https://www.youtube.com/watch?v=t1I1kdW3wgE 4 •November 2020 • Sidereal Times THE ALCORNER YOUR ASTRONOMICAL LEAGUE UPDate By Dawn Davies, AAS Astronomical League Correspondent (ALCOR) These are trying times we are in for the obvious reasons and because though we may be near our observing gear, constantly, the skies have not been too accommodating. That being said, there are still things you can do with your time indoors. Take this time to: • Catch up on reading the Astronomical League’s quarterly publication, The Reflector. Current and past issues can also be found on the AL’s website. • Complete those observing program logs you keep saying you are going to finish. • Submit a proposal for a new observing program, details and instructions here. • If you are working on your Herschel II, click here to read about upgrades to the list. As most of you may know, the Astronomical League Convention in Albuquerque has been cancelled. And while we were unable to hold our Messer Marathon last month, rest assured that the first chance for us to meet in person and observe together again at Bad Wolf Ranch will be a night to celebrate.
Recommended publications
  • A Tejútrendszer Szerkezete Tóth L

    A Tejútrendszer Szerkezete Tóth L

    A Tejútrendszer szerkezete Tóth L. Viktor XML to PDF by RenderX XEP XSL-FO F ormatter, visit us at http://www.renderx.com/ A Tejútrendszer szerkezete Tóth L. Viktor Szerzői jog © 2013 Eötvös Loránd Tudományegyetem E könyv kutatási és oktatási célokra szabadon használható. Bármilyen formában való sokszorosítása a jogtulajdonos írásos engedélyéhez kötött. Készült a TÁMOP-4.1.2.A/1-11/1-2011-0073 számú, „E-learning természettudományos tartalomfejlesztés az ELTE TTK-n” című projekt keretében. Konzorciumvezető: Eötvös Loránd Tudományegyetem, konzorciumi tagok: ELTE TTK Hallgatói Alapítvány, ITStudy Hungary Számítástechnikai Oktató- és Kutatóközpont Kft. XML to PDF by RenderX XEP XSL-FO F ormatter, visit us at http://www.renderx.com/ Tartalom Előszó ........................................................................................................................................ vii A Tejútrendszer korai kutatásának néhány érdekessége ...................................................................... viii Referenciák és további olvasnivaló: .......................................................................................... xi 1. A Tejútrendszer alapvonásai ......................................................................................................... 1 1.1 Alapvető paraméterek ....................................................................................................... 1 1.2 Alrendszerek .................................................................................................................... 3 1.2.1.
  • Annual Report 1995 1996

    Annual Report 1995 1996

    ISAAC NEWTON GROUP OF TELESCOPES La Palma Annual Report 1995 1996 Published in Spain by the Isaac Newton Group of Telescopes (ING) Legal License: Apartado de Correos 321 E38700 Santa Cruz de La Palma Spain Phone: +34 922 405655, 425400 Fax: +34 922 425401 URL: http://www.ing.iac.es/ Editor and Designer: J Méndez ([email protected]) Preprinting: Palmedición, S. L. Printing: Litografía La Palma, S.L. Front Cover: Photo-composition made by Nik Szymanek (of the amateur UK Deep Sky CCD imaging team of Nik Szymanek and Ian King) in summer 1997. The telescope shown here is the William Herschel Telescope. Note: Pictures on page 4 are courtesy of Javier Méndez, and pictures on page 34 are courtesy of Neil OMahoney (top) and Steve Unger (bottom). ISAAC NEWTON GROUP OF TELESCOPES Annual Report of the PPARC-NWO Joint Steering Committee 1995-1996 Isaac Newton Group William Herschel Telescope Isaac Newton Telescope Jacobus Kapteyn Telescope 4 ING ANNUAL R EPORT 1995-1996 of Telescopes The Isaac Newton Group of telescopes (ING) consists of the 4.2m William Herschel Telescope (WHT), the 2.5m Isaac Newton Telescope (INT) and the 1.0m Jacobus Kapteyn Telescope (JKT), and is located 2350m above sea level at the Roque de Los Muchachos Observatory (ORM) on the island of La Palma, Canary Islands. The WHT is the largest telescope in Western Europe. The construction, operation, and development of the ING telescopes is the result of a collaboration between the UK, Netherlands and Eire. The site is provided by Spain, and in return Spanish astronomers receive 20 per cent of the observing time on the telescopes.
  • Homogeneous Distances to Several Stellar Groups in the Second Galactic Quadrant

    Homogeneous Distances to Several Stellar Groups in the Second Galactic Quadrant

    International Journal of Astronomy and Astrophysics, 2013, 3, 10-17 http://dx.doi.org/10.4236/ijaa.2013.33A002 Published Online July 2013 (http://www.scirp.org/journal/ijaa) Homogeneous Distances to Several Stellar Groups in the Second Galactic Quadrant Nadia Kaltcheva1, Kevin Moran1, Thomas Gehrman1, Valeri Golev2 1Department of Physics and Astronomy, University of Wisconsin Oshkosh, Oshkosh, USA 2Department of Astronomy, Faculty of Physics, St. Kliment Ohridski University of Sofia, Sofia, Bulgaria Email: [email protected], [email protected] Received March 29, 2013; revised April 30, 2013; accepted May 8, 2013 Copyright © 2013 Nadia Kaltcheva et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. ABSTRACT A photometric study in the uvbyβ system of a 20˚ × 20˚ field in direction of the Cas OB6 and Per OB1 associations is presented. All currently available uvbyβ photoelectric data are used to obtain homogeneous color excesses and distances of nearly 230 stars of spectral types O-B9. The double cluster h & χ Per, NGC 663 and NGC 1502 are well represented in our sample. The sample also contains the brightest members of the young open clusters IC 1805, IC 1848, St 2, St 7 and ASCC9. We found that, within the errors, h & χ Per, NGC 663, IC 1805, IC 1848 and ASCC9, together with the Per OB1 association are located at very similar distance moduli between 11.0 to 11.3 mag. Our results indicate that the distance spread among these objects is less than the previously estimated, suggested that they could represent star- forming complexes located at the same distance.
  • The Substructure and Halo Population of the Double Cluster $ H $ And

    The Substructure and Halo Population of the Double Cluster $ H $ And

    Astronomy & Astrophysics manuscript no. ms c ESO 2021 July 13, 2021 The substructure and halo population of the Double Cluster h and χ Persei Jing Zhong1, Li Chen1; 3, M.B.N. Kouwenhoven2, Lu Li1; 3, Zhengyi Shao1; 4 and Jinliang Hou1; 3 1 Key Laboratory for Research in Galaxies and Cosmology,Shanghai Astronomical Observatory,Chinese Academy of Sciences, 80 Nandan Road, Shanghai 200030, China, e-mail: [email protected],[email protected] 2 Department of Mathematical Sciences, Xi’an Jiaotong-Liverpool University, 111 Ren’ai Rd., Suzhou Dushu Lake Science and Education Innovation District, Suzhou Industrial Park, Suzhou 215123, China 3 School of Astronomy and Space Science, University of Chinese Academy of Sciences, No. 19A, Yuquan Road, Beijing 100049, China 4 Shanghai Key Lab for Astrophysics, 100 Guilin Road, Shanghai 200234, China ABSTRACT Context. The GAIA DR2 provides an ideal dataset for studying the stellar populations of open cluster at larger spatial scale, as the cluster member stars can be well identified by their location in the multi-dimensional observational parameter space with the high precision parameter measurements. Aims. In order to study the stellar population and possible substructures in the outskirts of Double Cluster h and χ Persei, we investi- gate using the GAIA DR2 data a sky area of about 7.5 degrees in radius around the Double Cluster cores. Methods. We identify member stars using various criteria, including their kinematics (viz, proper motion), individual parallaxes, as well as photometric properties. A total of 2186 member stars in the parameter space were identified as members.
  • 250+ Deep-Sky Objects Visible with 7X35 Binoculars and the Naked-Eye

    250+ Deep-Sky Objects Visible with 7X35 Binoculars and the Naked-Eye

    6726 1 Scott N. Harrington 2nd edition September, 2018 2 To my family, Who were always understanding of my excursions under the stars. To the late Jack Horkheimer, a.k.a. Star Gazer, Whose television show kept this young astronomer inspired during those crucial first years. I’ll never stop “looking up”. And in memory of my dog Nell, who kept me company many long evenings – especially the one just before she passed away peacefully at the age of fifteen. I owe her a thanks for helping me with my observations by making this young astronomer feel safe at night. You will always be my favorite of our dogs. 3 Acknowledgements Below is a list of books that I read (most for the first time) in the last few years. They were all deeply influential in helping me discover many of the toughest objects that fill out my list. I would like to note that one I have not read, but greatly look forward to doing so, is Richard P. Wilds Bright & Dark Nebulae: An Observers Guide to Understanding the Clouds of the Milky Way Galaxy. Atlas of the Messier Objects by Ronald Stoyan The Backyard Astronomer’s Guide* by Terence Dickinson and Alan Dyer Cosmic Challenge – The Ultimate Observing List for Amateurs by Philip S. Harrington Deep-Sky Companions: The Caldwell Objects by Stephen James O’Meara Deep-Sky Companions: Hidden Treasures by Stephen James O'Meara Deep-Sky Companions: The Messier Objects by Stephen James O’Meara Deep-Sky Companions: The Secret Deep by Stephen James O’Meara Deep-Sky Wonders by Sue French Observing Handbook and Catalogue of Deep-Sky Objects by Christian B.

  • Events: General Meeting : Monday, Feb 5, 2018 at the Temecula Library, Room B, 30600 Pauba Rd, at 7 Pm

    The monthly newsletter of the Temecula Valley Astronomers Feb 2018 Events: General Meeting : Monday, Feb 5, 2018 at the Temecula Library, Room B, 30600 Pauba Rd, at 7 pm. After the usual opening comments by President Mark Baker and "What's Up" by Skip Southwick, Clark Williams will speak on "Why Systems Form in Spinning Flat Disks and How That Led to the Discovery of Dark Matter". Please consider helping out at one of the many Star Parties coming up 29 Sep 2015 – NASA APOD - Supermoon Total over the next few months. For the Lunar Eclipse and Lightning Storm. Image Credit latest schedule, check the Calendar & Copyright: Jose Antonio Hervás on the web page. WHAT’S INSIDE THIS MONTH: General information: Subscription to the TVA is included in the annual $25 membership (regular members) donation ($9 student; $35 Cosmic Comments family). by President Mark Baker Looking Up Redux President: Mark Baker 951-691-0101 by Clark Williams <[email protected]> Random Thoughts Vice President: Skip Southwick <[email protected]> by Chuck Dyson Past President: John Garrett <[email protected]> Sixty Years of Observing Our Earth Treasurer: Curtis Croulet <[email protected]> by Teagan Wall Secretary: Deborah Cheong <[email protected]> Club Librarian: Bob Leffler <[email protected]> Facebook: Tim Deardorff <[email protected]> Star Party Coordinator and Outreach: Deborah Cheong Send newsletter submissions to Mark DiVecchio <[email protected]> <[email protected]> by the 20th of the month for the next month's issue. Address renewals or other correspondence to: Temecula Valley Astronomers PO Box 1292 Like us on Facebook Murrieta, CA 92564 Member’s Mailing List: [email protected] Website: http://www.temeculavalleyastronomers.com/ Page 1 of 12 The monthly newsletter of the Temecula Valley Astronomers Feb 2018 Cosmic Comments by President Mark Baker OUTREACH…!!! A simple word that defines the lifeblood of our organization.
  • Star Formation Influenced by OB Stars

    Star Formation Influenced by OB Stars

    Interstellar Matter and Star Formation: A Multi-wavelength Perspective ASI Conference Series, 2010, Vol. 1, pp 11{17 Edited by D. K. Ojha Star formation influenced by OB stars Wen Ping Chen¤ Graduate Institute of Astronomy, National Central University, Jhongli 32054, Taiwan Abstract. Given proper conditions, a massive star can play a con- structive role in producing next-generation stars, thereby sustaining the star formation activity in a giant molecular cloud. We outline here a few examples where such triggered starbirth takes place in the peripherals, and in the remnants, of a molecular cloud. A supernova shock would have an even greater influence, inducing star formation out to hundreds of parsecs. Keywords : stars: formation, stars: pre-main-sequence, H II regions, ISM: clouds, ISM: bubbles 1. Triggered star formation by massive stars The stellar radiation and powerful wind from a massive star are devastating to its nearby molecular clouds so as to terminate any subsequent star formation. Working at a distance, however, the expanding bubble created by a massive star inside a molecular cloud, given proper conditions, may sweep to com- press the surrounding cloud material. When the collected gas and dust reaches the critical density and become gravitationally unstable, the cloud collapses to form next-generation stars. This ionization induced \collect-and-collapse" mechanism (Fig. 1; top) was ¯rst proposed by Elmegreen & Lada (1977), and later demonstrated observationally by Deharveng et al. (2005) and by Zavagno et al. (2006). Massive stars thus formed, may subsequently break out their own cavities. The cloud soon gets dispersed, and any remnant clouds are now exposed to the strong stellar ultraviolet radiation.
  • SAAO Astronomical History Symposium 2018

    SAAO Astronomical History Symposium 2018

    Volume 77 Nos 3 & 4 April 2018 Volume 77 Nos 3 & 4 April 2018 CONTENTS News Note: MeerKAT observes a rare burst of activity from a Magnetar ........ 23 Nova ASASSN-18fv in Carina ........................................................................... 25 SAAO Astronomical History Symposium 2018 ................................................. 29 11 th ASSA Symposium 2018 ............................................................................. 37 Note: Star Charts ............................................................................................. 47 Recent Southern African Fireball Observations ............................................... 48 Obituary - Malcolm Andre Le Fraper Gray ....................................................... 53 Colloquia ......................................................................................................... 54 Sky Delights: Perseus the Young Man .............................................................. 58 In this issue: MeerKAT observes unusual activity from a Magnetar Nova ASASSN-18fv in Carina SAAO History Symposium 2018 11 th ASSA Symposium Fireball Observations - Obituary Andrew Gray The Astronomical Society of Southern Africa (ASSA) was formed in 1922 by the amalgamation of the Cape Astronomical Association (founded 1912) and the Johannesburg Astronomical Association (founded 1918). It is a body consisting of both amateur and professional astronomers. EDI TORIAL OARD Mr Case Rijsdijk (Editor, MNASSA ) Publications : The Society publishes its electronic journal,
  • THE STAR FORMATION NEWSLETTER an Electronic Publication Dedicated to Early Stellar Evolution and Molecular Clouds

    THE STAR FORMATION NEWSLETTER an Electronic Publication Dedicated to Early Stellar Evolution and Molecular Clouds

    THE STAR FORMATION NEWSLETTER An electronic publication dedicated to early stellar evolution and molecular clouds No. 185 — 23 Mar 2008 Editor: Bo Reipurth ([email protected]) Call for Contributions to A White Paper on Star Formation Studies with SIM The Space Interferometer Mission (SIM) is designed to carry out astrometric measurements of objects with brightness levels ranging from V = −1 mag to 19 mag with an astrometric accuracy of ∼ 4 µas (end of mission) relative to an absolute reference frame and < 0.1 µas (end of mission) for relative measurements between targets and reference stars within a ∼ 1o field of view. Among SIM’s goals are searches for planets with masses comparable to that of the Earth in the habitable zones of nearby stars, and for gas and icy giant planets around young stars (Beichman et al 2008, IAU 248, in press; Tanner et al 2007, PASP 119,747). SIM will also carry out observing programs covering many aspects of stellar astronomy, galactic astronomy and even cosmology. SIM’s science program is described in Unwin et al. (2008, PASP, 120, 38; http://www.journals.uchicago.edu/doi/abs/10.1086/525059)and was endorsed by the 1990 and 2000 NAS/NRC decadal reviews. Most recently, the potential of an astrometric mission with SIM’s capabilities for planet detection has been endorsed by the Exo-Planet Task Force of the Astronomy and Astrophysics Advisory Committee (AAAC; http://www.nsf.gov/mps/ast/aaac/exoplanet task force/reports/aaac draft.pdf). There remains significant unallocated observing time for which NASA will eventually solicit observing time requests for new Key Projects and/or smaller General Observer programs.
  • Substructure and Halo Population of Double Cluster H and Χ Persei

    Substructure and Halo Population of Double Cluster H and Χ Persei

    A&A 624, A34 (2019) Astronomy https://doi.org/10.1051/0004-6361/201834334 & c ESO 2019 Astrophysics Substructure and halo population of Double Cluster h and χ Persei Jing Zhong1, Li Chen1,3, M. B. N. Kouwenhoven2, Lu Li1,3, Zhengyi Shao1,4, and Jinliang Hou1,3 1 Key Laboratory for Research in Galaxies and Cosmology, Shanghai Astronomical Observatory, Chinese Academy of Sciences, 80 Nandan Road, Shanghai 200030, PR China e-mail: [email protected], [email protected] 2 Department of Mathematical Sciences, Xi’an Jiaotong-Liverpool University, 111 Ren’ai Rd., Suzhou Dushu Lake Science and Education Innovation District, Suzhou Industrial Park, Suzhou 215123, PR China 3 School of Astronomy and Space Science, University of Chinese Academy of Sciences, No. 19A, Yuquan Road, Beijing 100049, PR China 4 Shanghai Key Lab for Astrophysics, 100 Guilin Road, Shanghai 200234, PR China Received 27 September 2018 / Accepted 18 February 2019 ABSTRACT Context. Gaia DR2 provides an ideal dataset to study the stellar populations of open clusters at larger spatial scales because the cluster member stars can be well identified by their location in the multidimensional observational parameter space with high precision parameter measurements. Aims. In order to study the stellar population and possible substructures in the outskirts of Double Cluster h and χ Persei, we use Gaia DR2 data in a sky area of about 7.5◦ in radius around the Double Cluster cores. Methods. We identified member stars using various criteria, including their kinematics (namely, proper motion), individual parallaxes, and photometric properties. A total of 2186 member stars in the parameter space were identified as members.
  • The Stellar Population of H and Chi Persei: Cluster Properties

    The Stellar Population of H and Chi Persei: Cluster Properties

    The Stellar Population of h and χ Persei: Cluster Properties, Membership, and the Intrinsic Colors and Temperatures of Stars Thayne Currie1,7, Jesus Hernandez2, Jonathan Irwin1,3 Scott J. Kenyon1, Susan Tokarz1, Zoltan Balog4, Ann Bragg5,Perry Berlind6, and Mike Calkins6 [email protected], [email protected], [email protected] ABSTRACT From photometric observations of ∼ 47,000 stars and spectroscopy of ∼ 11,000 stars, we describe the first extensive study of the stellar population of the famous Double Cluster, h and χ Persei, down to subsolar masses. By analyzing optical spectra and optical/infrared photometry, we constrain the distance moduli (dM), reddening (E(B-V)), and ages for h Persei, χ Persei and the low-density halo pop- ulation surrounding both cluster cores. With the exception of mass and spatial distribution, the clusters are nearly identical in every measurable way. Both clus- ters have E(B-V) ∼ 0.52–0.55 and dM = 11.8–11.85; the halo population, while more poorly constrained, likely has identical properties. As determined from the main sequence turnoff, the luminosity of M supergiants, and pre-main sequence isochrones, ages for h Persei, χ Persei and the halo population all converge on ≈ 14 Myr, thus showing a stunning agreement between estimates based on en- tirely different physics. From these data, we establish the first spectroscopic and photometric membership lists of cluster stars down to early/mid M dwarfs. At minimum, there are ∼ 5,000 members within 10’ of the cluster centers, while the entire h and χ Persei region has at least ∼ 13,000 and as many as 20,000 members.
  • Eclipsing Binaries in Open Clusters. I. V615 Per and V618 Per in H Persei ?

    Eclipsing Binaries in Open Clusters. I. V615 Per and V618 Per in H Persei ?

    Mon. Not. R. Astron. Soc. 000, 000–000 (0000) Printed 29 November 2005 (MN LATEX style file v2.2) Eclipsing binaries in open clusters. I. V615 Per and V618 Per in h Persei ? J. Southworth1†, P. F. L. Maxted1† and B. Smalley1† 1 Department of Physics and Chemistry, Keele University, Staffordshire, ST5 5BG, UK 29 November 2005 ABSTRACT We have derived absolute dimensions for two early-type main sequence detached eclips- ing binaries in the young open cluster h Persei (NGC 869). V615 Persei has a spectral type of B7 V and a period of 13.7 days. V618 Persei is A2 V and has a period of 6.4 days. New ephemerides are calculated for both systems. The masses of the component stars have been derived using high-resolution spectroscopy and are 4.08 ± 0.06 M¯ and 3.18 ± 0.05 M¯ for V615 Per and 2.33 ± 0.03 M¯ and 1.56 ± 0.02 M¯ for V618 Per. The radii have been measured by fitting the available light curves using ebop and are 2.29 ± 0.14 R¯ and 1.90 ± 0.09 R¯ for V615 Per and 1.64 ± 0.07 R¯ and 1.32 ± 0.07 R¯ for V618 Per. By comparing the observed spectra of V615 Per to synthetic spectra from model atmospheres we find that the effective temperatures of the stars are 15 000 ± 500 K for the primary and 11 000 ± 500 K for the secondary. The equato- rial rotational velocities of the primary and secondary components of V615 Per are 28 ± 5 km s−1 and 8 ± 5 km s−1, respectively.