DOCSLIB.ORG

260 — 14 August 2014 Editor: Bo Reipurth ([email protected]) List of Contents

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
260 — 14 August 2014 Editor: Bo Reipurth (Reipurth@Ifa.Hawaii.Edu) List of Contents THE STAR FORMATION NEWSLETTER An electronic publication dedicated to early stellar/planetary evolution and molecular clouds No. 260 — 14 August 2014 Editor: Bo Reipurth ([email protected]) List of Contents The Star Formation Newsletter Interview ...................................... 3 My Favorite Object ............................ 6 Editor: Bo Reipurth [email protected] Perspective ................................... 12 Technical Editor: Eli Bressert Abstracts of Newly Accepted Papers .......... 17 [email protected] Meetings ..................................... 56 Technical Assistant: Hsi-Wei Yen New and Upcoming Meetings ................. 58 [email protected] Short Announcements ........................ 59 Editorial Board Joao Alves Alan Boss Jerome Bouvier Cover Picture Lee Hartmann Thomas Henning The cover shows the W5-NE region, a bridge of Paul Ho molecular cloud separating the HII regions/clusters Jes Jorgensen W5-W (IC 1848) and W5-E (AFGL 4029). The im- Charles J. Lada age is about 12 × 14 arcmin, corresponding to ap- Thijs Kouwenhoven proximately 0.11 × 0.13 pc at the assumed distance Michael R. Meyer of 1.95 kpc. The bright star at the center of the im- Ralph Pudritz age is BD +60◦596, a B1V star which has created Luis Felipe Rodr´ıguez the cavity seen in the image. Numerous young low- Ewine van Dishoeck mass stars are found in this region, including the Hans Zinnecker young variable LW Cas. East is up and north is right in this image. The Star Formation Newsletter is a vehicle for fast distribution of information of interest for as- Image courtesy Ken Crawford http://www.imagingdeepsky.com tronomers working on star and planet formation ( ) and molecular clouds. You can submit material for the following sections: Abstracts of recently accepted papers (only for papers sent to refereed journals), Abstracts of recently accepted major re- views (not standard conference contributions), Dis- sertation Abstracts (presenting abstracts of new Submitting your abstracts Ph.D dissertations), Meetings (announcing meet- ings broadly of interest to the star and planet for- Latex macros for submitting abstracts mation and early solar system community), New and dissertation abstracts (by e-mail to Jobs (advertising jobs specifically aimed towards [email protected]) are appended to persons within the areas of the Newsletter), and each Call for Abstracts. You can also Short Announcements (where you can inform or re- submit via the Newsletter web inter- quest information from the community). Addition- face at http://www2.ifa.hawaii.edu/star- ally, the Newsletter brings short overview articles formation/index.cfm on objects of special interest, physical processes or theoretical results, the early solar system, as well as occasional interviews. Newsletter Archive www.ifa.hawaii.edu/users/reipurth/newsletter.htm 2 the launch of IRAS. So we missed out on jets/disk winds, though I think our paper did provide some motivation for Lee Hartmann the X-wind model of Frank Shu and his collaborators. in conversation with Bo Reipurth The Alfven wave-driven wind models were also motivated by the need to produce massive flows in the absence of sig- nificant thermal and radiative driving, but in this case the stars were known to be slowly rotating, so we had to in- voke high-frequency, turbulently-produced waves. Work- ing first with Suzan Edwards and Gene Avrett, and then later with Nuria Calvet in the context of schematic disk winds, we could get emission line ratios fairly well, but the line profiles generally didn’t match the observations. Then in 1989 I was visiting Santa Cruz and mentioned the problem of the slow rotation of T Tauri stars to Doug Lin. Doug suggested that the slow rotation was a result of magnetospheric coupling which transferred excess stel- lar angular momentum to the disk. Cluelessly, I dismissed this idea because I thought making a magnetospheric hole in the disk should produce a gap in the near-IR infrared Q: Your early papers had nothing to do with young stars. spectral energy distribution that was not apparent... just How did you develop your interest in star formation? before Arieh K¨onigl’s paper came out on magnetospheric A: My early years were really kind of a random walk braking. (My mistake was to ignore emission from the through (mostly) stellar astrophysics. I worry a bit now directly-illuminated, hotter inner “wall” of the dust disk, about young people who don’t have the opportunity to which fills in the short-wavelength SED, as shown by An- try out different things until they find the subject that’s tonella Natta and collaborators.) I went back to Nuria best for them. Anyway, I had originally been working on and said, we’ve gotten this all wrong; we should be doing the theory of extended stellar atmospheres and winds as a models of (magnetospheric) infall, not outflow. Making grad student with Joe Cassinelli at Wisconsin, but decided this change resulted in very good agreement with many I needed some observational experience and worked with line profile observations, as ultimately developed in some Chris Anderson on spectra of flare stars. The resulting detail in James Muzerolle’s thesis work. thesis wasn’t very good but it introduced me to solar-type Q: Your first venture into observations of young stars magnetic activity. came with your 1982 paper on high resolution spectroscopy Then I went to CfA as a postdoc and began working with of T Tauri stars. Another large observational effort was Andrea Dupree on International Ultraviolet Explorer satel- your study of rotational and radial velocities of T Tauri lite observations of all kinds of objects - globular clusters, stars. What motivated you to embark on observations? X-ray binaries, cataclysmic variables, you name it, along A: New detectors became available at Mt. Hopkins, ver- with John Raymond. My major focus eventually became sions of the intensified Reticon developed by Steve Schecht- chromospheric and coronal emission of solar-type stars, man. The Reticons were solid-state 2 x 1024 pixel arrays, which then led to my interest in T Tauri stars, which kind of forerunners of CCDs, but had huge read noise. To were supposed to be the most magnetically-active late- get around that problem, the Reticon was placed at the type stars... but that isn’t the big story. back end of a collection of image tubes (pause for young Q: In the early 1980s you wrote a series of highly influen- readers, if any, to google the term), which turned each in- tial papers with MacGregor on wave-driven winds. coming photon into a huge spray at the Reticon, defeating the read noise and allowing one to count individual pho- A: Keith had worked on rotating, magnetized solar-type tons. It was a huge improvement over what we had before, wind models for his thesis, and applied these to the very not only because of increased sensitivity but because the massive outflow in Orion-KL, showing that a magnetized data went straight into the computer without the need to protostellar cloud rotating at breakup could drive a mas- scan plates. I figured it would be useful to have a kind sive wind. But we did this for equatorial flow; at roughly of album of T Tauri line profiles using this new device. the same time the Blandford and Payne and Pudritz and In particular, I remember an Hγ profile of DF Tau where Norman papers came out on disk winds/jets driven by it showed simultaneous red- and blue-shifted absorption, magnetic fields anchored in the rotating disk. The im- and puzzling over it. Of course now we can interpret this portance of disks only became clear somewhat later with as magnetospheric infall interior to an expanding wind. 3 I think my interest in making a survey of rotation in T the infrared spectrum. As far as I know, the most compre- Tauri stars stemmed from my collaboration with John hensive comparison of a detailed SED with a steady disk Stauffer, who was leading efforts to study the subset of model for any astrophysical object is for FU Ori; as shown rapidly-rotating solar-type stars in the Pleiades. Prob- in the right panel of Figure 1 of arXiv:1106.3343, we can ably the idea was to see how initial angular momenta fit the observations over a factor of 30 in wavelength in- mapped into the Pleiades rotation allowing for contrac- cluding the absorption bands in the near- to mid-infrared. tion to the main sequence and seeing how much angular Zhaohuan Zhu, Catherine Espaillat, Ken Hinkle and I also momentum loss via winds one needed. Along with Jerome showed that the differential rotational velocities remain Bouvier’s simultaneous study, we showed the slow T Tauri consistent with Keplerian out to 4.6µm. No other model rotation more systematically than had been done before. explains all these results. (Although magnetospheric braking probably is responsi- Modeling the optical spectral lines accurately involves sev- ble for the slow rotation, exactly how it works still puz- eral subtleties, such as accounting for the non-power-law zles me.) On a personal note, it engendered about the temperature distribution of the inner disk, and in the case worst referee report I’ve ever gotten, with 70 paragraphs of FU Ori, correcting for the Doppler shifts of the emerging (I counted) of scathing criticism. I was ready to jump off disk wind. That said, the mechanism(s) of the outbursts a bridge until I received a very nice letter from George still remain unclear. Perhaps the ongoing discovery and Herbig, who liked the paper. That meant a lot to me. characterization of the weaker EXor outbursts will help. Q: In 1985 came your paper with Scott Kenyon on the na- Q: Your most cited first-author paper, together with Nuria ture of FU Orionis objects, followed by a series of studies Calvet and collaborators, is the 1998 study ′Accretion and of FUors, and culminating in your Annual Reviews article the Evolution of T Tauri Disks′.
Load more

Recommended publications
  • Stability of Planets in Binary Star Systems
    StabilityStability ofof PlanetsPlanets inin BinaryBinary StarStar SystemsSystems Ákos Bazsó in collaboration with: E. Pilat-Lohinger, D. Bancelin, B. Funk ADG Group Outline Exoplanets in multiple star systems Secular perturbation theory Application: tight binary systems Summary + Outlook About NFN sub-project SP8 “Binary Star Systems and Habitability” Stand-alone project “Exoplanets: Architecture, Evolution and Habitability” Basic dynamical types S-type motion (“satellite”) around one star P-type motion (“planetary”) around both stars Image: R. Schwarz Exoplanets in multiple star systems Observations: (Schwarz 2014, Binary Catalogue) ● 55 binary star systems with 81 planets ● 43 S-type + 12 P-type systems ● 10 multiple star systems with 10 planets Example: γ Cep (Hatzes et al. 2003) ● RV measurements since 1981 ● Indication for a “planet” (Campbell et al. 1988) ● Binary period ~57 yrs, planet period ~2.5 yrs Multiplicity of stars ~45% of solar like stars (F6 – K3) with d < 25 pc in multiple star systems (Raghavan et al. 2010) Known exoplanet host stars: single double triple+ source 77% 20% 3% Raghavan et al. (2006) 83% 15% 2% Mugrauer & Neuhäuser (2009) 88% 10% 2% Roell et al. (2012) Exoplanet catalogues The Extrasolar Planets Encyclopaedia http://exoplanet.eu Exoplanet Orbit Database http://exoplanets.org Open Exoplanet Catalogue http://www.openexoplanetcatalogue.com The Planetary Habitability Laboratory http://phl.upr.edu/home NASA Exoplanet Archive http://exoplanetarchive.ipac.caltech.edu Binary Catalogue of Exoplanets http://www.univie.ac.at/adg/schwarz/multiple.html Habitable Zone Gallery http://www.hzgallery.org Binary Catalogue Binary Catalogue of Exoplanets http://www.univie.ac.at/adg/schwarz/multiple.html Dynamical stability Stability limit for S-type planets Rabl & Dvorak (1988), Holman & Wiegert (1999), Pilat-Lohinger & Dvorak (2002) Parameters (a , e , μ) bin bin Outer limit at roughly max.
    [Show full text]
  • Naming the Extrasolar Planets
    Naming the extrasolar planets W. Lyra Max Planck Institute for Astronomy, K¨onigstuhl 17, 69177, Heidelberg, Germany [email protected] Abstract and OGLE-TR-182 b, which does not help educators convey the message that these planets are quite similar to Jupiter. Extrasolar planets are not named and are referred to only In stark contrast, the sentence“planet Apollo is a gas giant by their assigned scientific designation. The reason given like Jupiter” is heavily - yet invisibly - coated with Coper- by the IAU to not name the planets is that it is consid- nicanism. ered impractical as planets are expected to be common. I One reason given by the IAU for not considering naming advance some reasons as to why this logic is flawed, and sug- the extrasolar planets is that it is a task deemed impractical. gest names for the 403 extrasolar planet candidates known One source is quoted as having said “if planets are found to as of Oct 2009. The names follow a scheme of association occur very frequently in the Universe, a system of individual with the constellation that the host star pertains to, and names for planets might well rapidly be found equally im- therefore are mostly drawn from Roman-Greek mythology. practicable as it is for stars, as planet discoveries progress.” Other mythologies may also be used given that a suitable 1. This leads to a second argument. It is indeed impractical association is established. to name all stars. But some stars are named nonetheless. In fact, all other classes of astronomical bodies are named.
    [Show full text]
  • Elemental Abundances of Low-Mass Stars in the Young Clusters 25 Ori
    Astronomy & Astrophysics manuscript no. Biazzoetal˙Mar2011˙noref c ESO 2018 October 16, 2018 Elemental abundances of low-mass stars in the young clusters 25 Ori and λ Ori⋆ K. Biazzo1, S. Randich1, F. Palla1, and C. Brice˜no2 1 INAF - Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50125 Firenze, Italy 2 CIDA - Centro de Investigaciones de Astronom`ıa, Apartado Postal 264, M´erida 5101-A, Venezuela Received / accepted ABSTRACT Aims. We aim to derive the chemical pattern of the young clusters 25 Orionis and λ Orionis through homogeneous and accurate measurements of elemental abundances. Methods. We present flames/uves observations of a sample of 14 K-type targets in the 25 Ori and λ Ori clusters; we measure their radial velocities, in order to confirm cluster membership. We derive stellar parameters and abundances of Fe, Na, Al, Si, Ca, Ti, and Ni using the code MOOG. Results. All the 25 Ori stars are confirmed cluster members without evidence of binarity; in λ Ori we identify one non-member and one candidate single-lined binary star. We find an average metallicity [Fe/H]=−0.05 ± 0.05 for 25 Ori, where the error is the 1σ standard deviation from the average. λ Ori members have a mean iron abundance value of 0.01 ± 0.01. The other elements show close-to-solar ratios and no star-to-star dispersion. Conclusions. Our results, along with previous metallicity determinations in the Orion complex, evidence a small but detectable dispersion in the [Fe/H] distribution of the complex. This appears to be compatible with large-scale star formation episodes and initial non-uniformity in the pre-cloud medium.
    [Show full text]
  • POSTERS SESSION I: Atmospheres of Massive Stars
    Abstracts of Posters 25 POSTERS (Grouped by sessions in alphabetical order by first author) SESSION I: Atmospheres of Massive Stars I-1. Pulsational Seeding of Structure in a Line-Driven Stellar Wind Nurdan Anilmis & Stan Owocki, University of Delaware Massive stars often exhibit signatures of radial or non-radial pulsation, and in principal these can play a key role in seeding structure in their radiatively driven stellar wind. We have been carrying out time-dependent hydrodynamical simulations of such winds with time-variable surface brightness and lower boundary condi- tions that are intended to mimic the forms expected from stellar pulsation. We present sample results for a strong radial pulsation, using also an SEI (Sobolev with Exact Integration) line-transfer code to derive characteristic line-profile signatures of the resulting wind structure. Future work will compare these with observed signatures in a variety of specific stars known to be radial and non-radial pulsators. I-2. Wind and Photospheric Variability in Late-B Supergiants Matt Austin, University College London (UCL); Nevyana Markova, National Astronomical Observatory, Bulgaria; Raman Prinja, UCL There is currently a growing realisation that the time-variable properties of massive stars can have a funda- mental influence in the determination of key parameters. Specifically, the fact that the winds may be highly clumped and structured can lead to significant downward revision in the mass-loss rates of OB stars. While wind clumping is generally well studied in O-type stars, it is by contrast poorly understood in B stars. In this study we present the analysis of optical data of the B8 Iae star HD 199478.
    [Show full text]
  • Transactions 1905
    THE Royal Astronomical Society of Canada TRANSACTIONS FOR 1905 (INCLUDING SELECTED PAPERS AND PROCEEDINGS) EDITED BY C. A CHANT. TORONTO: ROYAL ASTRONOMICAL PRINT, 1906. The Royal Astronomical Society of Canada. THE Royal Astronomical Society of Canada TRANSACTIONS FOR 1905 (INCLUDING SELECTED PAPERS AND PROCEEDINGS) EDITED BY C. A CHANT. TORONTO: ROYAL ASTRONOMICAL PRINT, 1906. TABLE OF CONTENTS. The Dominion Observatory, Ottawa (Frontispiece) List of Officers, Fellows and A ssociates..................... - - 3 Treasurer’s R eport.....................--------- 12 President’s Address and Summary of Work ------ 13 List of Papers and Lectures, 1905 - - - - ..................... 26 The Dominion Observatory at Ottawa - - W. F. King 27 Solar Spots and Magnetic Storms for 1904 Arthur Harvey 35 Stellar Legends of American Indians - - J. C. Hamilton 47 Personal Profit from Astronomical Study - R. Atkinson 51 The Eclipse Expedition to Labrador, August, 1905 A. T. DeLury 57 Gravity Determinations in Labrador - - Louis B. Stewart 70 Magnetic and Meteorological Observations at North-West River, Labrador - - - - R. F. Stupart 97 Plates and Filters for Monochromatic and Three-Color Photography of the Corona J. S. Plaskett 89 Photographing the Sun and Moon with a 5-inch Refracting Telescope . .......................... D. B. Marsh 108 The Astronomy of Tennyson - - - - John A. Paterson 112 Achievements of Nineteenth Century Astronomy , L. H. Graham 125 A Lunar Tide on Lake Huron - - - - W. J. Loudon 131 Contributions...............................................J. Miller Barr I. New Variable Stars - - - - - - - - - - - 141 II. The Variable Star ξ Bootis -------- 143 III. The Colors of Helium Stars - - - ..................... 144 IV. A New Problem in Solar Physics ------ 146 Stellar Classification ------ W. Balfour Musson 151 On the Possibility of Fife in Other Worlds A.
    [Show full text]
  • INAUGURAL – DISSERTATION Dipl.-Phys. Alexander A. Schegerer
    INAUGURAL – DISSERTATION zur Erlangung der Doktorwurde¨ der Naturwissenschaftlich-Mathematischen Gesamtfakult¨at der Ruprecht - Karls - Universit¨at Heidelberg vorgelegt von Dipl.-Phys. Alexander A. Schegerer, geboren in Kaufbeuren Tag der mundlichen¨ Prufung:¨ 17. Oktober 2007 II Struktur- und Staubentwicklung in zirkumstellaren Scheiben um T Tauri-Sterne Analyse und Modellierung hochaufl¨osender Beobachtungen in verschiedenen Wellenl¨angenbereichen Gutachter: Prof. Dr. Thomas Henning Prof. Dr. Wolfgang Duschl IV Meinen Eltern, Maria-Christa und Wolfgang Schegerer, gewidmet. VI Thema Im Zentrum dieser Doktorarbeit steht die Untersuchung der inneren Strukturen zirkumstella- rer Scheiben um T Tauri-Sterne sowie die Analyse zirkumstellarer Staub- und Eisteilchen und ihres Einflusses auf die Scheibenstruktur. Unter Zuhilfenahme von theoretisch berechneten Vergleichsspektren gibt der Verlauf der 10 µm-Emissionsbande in den Spektren junger stellarer Objekte Hinweise auf den Entwick- lungsgrad von Silikatstaub. Die Silikatbanden von 27 T Tauri-Objekten werden analysiert, um nach potentiell vorliegenden Korrelationen zwischen der Silikatstaubzusammensetzung und den stellaren Eigenschaften zu suchen. Analog erlaubt das Absorptionsband bei 3 µm, das dem Wassereis zugeschrieben wird, eine Untersuchung der Entwicklung von Eisk¨ornern in jungen stellaren Objekten. Erstmals ist es gelungen, kristallines Wassereis im Spektrum eines T Tauri-Objektes nachzuweisen. Unser wichtigstes Hilfsmittel zur Analyse der Temperatur- und Dichtestrukturen zirkum- stellarer
    [Show full text]
  • Exoplanet.Eu Catalog Page 1 # Name Mass Star Name
    exoplanet.eu_catalog # name mass star_name star_distance star_mass OGLE-2016-BLG-1469L b 13.6 OGLE-2016-BLG-1469L 4500.0 0.048 11 Com b 19.4 11 Com 110.6 2.7 11 Oph b 21 11 Oph 145.0 0.0162 11 UMi b 10.5 11 UMi 119.5 1.8 14 And b 5.33 14 And 76.4 2.2 14 Her b 4.64 14 Her 18.1 0.9 16 Cyg B b 1.68 16 Cyg B 21.4 1.01 18 Del b 10.3 18 Del 73.1 2.3 1RXS 1609 b 14 1RXS1609 145.0 0.73 1SWASP J1407 b 20 1SWASP J1407 133.0 0.9 24 Sex b 1.99 24 Sex 74.8 1.54 24 Sex c 0.86 24 Sex 74.8 1.54 2M 0103-55 (AB) b 13 2M 0103-55 (AB) 47.2 0.4 2M 0122-24 b 20 2M 0122-24 36.0 0.4 2M 0219-39 b 13.9 2M 0219-39 39.4 0.11 2M 0441+23 b 7.5 2M 0441+23 140.0 0.02 2M 0746+20 b 30 2M 0746+20 12.2 0.12 2M 1207-39 24 2M 1207-39 52.4 0.025 2M 1207-39 b 4 2M 1207-39 52.4 0.025 2M 1938+46 b 1.9 2M 1938+46 0.6 2M 2140+16 b 20 2M 2140+16 25.0 0.08 2M 2206-20 b 30 2M 2206-20 26.7 0.13 2M 2236+4751 b 12.5 2M 2236+4751 63.0 0.6 2M J2126-81 b 13.3 TYC 9486-927-1 24.8 0.4 2MASS J11193254 AB 3.7 2MASS J11193254 AB 2MASS J1450-7841 A 40 2MASS J1450-7841 A 75.0 0.04 2MASS J1450-7841 B 40 2MASS J1450-7841 B 75.0 0.04 2MASS J2250+2325 b 30 2MASS J2250+2325 41.5 30 Ari B b 9.88 30 Ari B 39.4 1.22 38 Vir b 4.51 38 Vir 1.18 4 Uma b 7.1 4 Uma 78.5 1.234 42 Dra b 3.88 42 Dra 97.3 0.98 47 Uma b 2.53 47 Uma 14.0 1.03 47 Uma c 0.54 47 Uma 14.0 1.03 47 Uma d 1.64 47 Uma 14.0 1.03 51 Eri b 9.1 51 Eri 29.4 1.75 51 Peg b 0.47 51 Peg 14.7 1.11 55 Cnc b 0.84 55 Cnc 12.3 0.905 55 Cnc c 0.1784 55 Cnc 12.3 0.905 55 Cnc d 3.86 55 Cnc 12.3 0.905 55 Cnc e 0.02547 55 Cnc 12.3 0.905 55 Cnc f 0.1479 55
    [Show full text]
  • The Orbital Motion of the Quintuplet Cluster—A Common Origin for the Arches and Quintuplet Clusters?∗
    The Astrophysical Journal, 789:115 (20pp), 2014 July 10 doi:10.1088/0004-637X/789/2/115 C 2014. The American Astronomical Society. All rights reserved. Printed in the U.S.A. THE ORBITAL MOTION OF THE QUINTUPLET CLUSTER—A COMMON ORIGIN FOR THE ARCHES AND QUINTUPLET CLUSTERS?∗ A. Stolte1,B.Hußmann1, M. R. Morris2,A.M.Ghez2, W. Brandner3,J.R.Lu4, W. I. Clarkson5, M. Habibi1, and K. Matthews6 1 Argelander Institut fur¨ Astronomie, Auf dem Hugel¨ 71, D-53121 Bonn, Germany; [email protected] 2 Division of Astronomy and Astrophysics, UCLA, Los Angeles, CA 90095-1547, USA; [email protected], [email protected] 3 Max-Planck-Institut fur¨ Astronomie, Konigstuhl¨ 17, D-69117 Heidelberg, Germany; [email protected] 4 Institute for Astronomy, University of Hawai’i, 2680 Woodlawn Drive, Honolulu, HI 96822, USA; [email protected] 5 Department of Natural Sciences, University of Michigan-Dearborn, 125 Science Building, 4901 Evergreen Road, Dearborn, MI 48128, USA; [email protected] 6 Caltech Optical Observatories, California Institute of Technology, MS 320-47, Pasadena, CA 91225, USA; [email protected] Received 2014 January 16; accepted 2014 May 14; published 2014 June 20 ABSTRACT We investigate the orbital motion of the Quintuplet cluster near the Galactic center with the aim of constraining formation scenarios of young, massive star clusters in nuclear environments. Three epochs of adaptive optics high-angular resolution imaging with the Keck/NIRC2 and Very Large Telescope/NAOS-CONICA systems were obtained over a time baseline of 5.8 yr, delivering an astrometric accuracy of 0.5–1 mas yr−1.
    [Show full text]
  • The Southern Flanking Fields of the 25 Orionis Group
    The Southern Flanking Fields of the 25 Orionis Group Peregrine M. McGehee1 ABSTRACT The stellar group surrounding the Be (B1Vpe) star 25 Orionis was discov- ered to be a pre-main-sequence population by the Centro de Investigaciones de Astronomia (CIDA) Orion Variability Survey and subsequent spectroscopy. We analyze Sloan Digital Sky Survey multi-epoch photometry to map the southern extent of the 25 Ori group and to characterize its pre-main-sequence population. We compare this group to the neighboring Orion OB1a and OB1b subassociations and to active star formation sites (NGC 2068/NGC 2071) within the Lynds 1630 dark cloud. We find that the 25 Ori group has a radius of 1.4◦, corresponding to 8-11 pc at the distances of Orion OB1a and OB1b. Given that the characteristic sizes of young open clusters are a few pc or less this suggests that 25 Ori is an unbound association rather than an open cluster. Due to its PMS population having a low Classical T Tauri fraction (∼10%) we conclude that the 25 Ori group is of comparable age to the 11 Myr Orion OB1a subassociation. Subject headings: open clusters and associations: individual (25 Orionis) – stars: formation – stars: late-type – stars: low-mass, brown dwarfs – stars: pre-main- sequence 1. Introduction arXiv:astro-ph/0603317v1 13 Mar 2006 The pre-main-sequence 25 Orionis group has been recently identified by the Centro de Investigaciones de Astronomia Variability Survey of Orion (CVSO; Brice˜no et al. 2005a) on the basis of multi-epoch imaging and follow-up spectroscopy. 25 Ori has also been noted by Kharchenko et al.
    [Show full text]
  • Übersicht NGC-Objektauswahl Cepheus Zur Übersichtskarte
    NGC-Objektauswahl Cepheus NGC 40 NGC 7055 NGC 7354 NGC 188 NGC 7076 NGC 7380 NGC 1184 NGC 7129 NGC 7419 NGC 1544 NGC 7139 NGC 7423 NGC 2276 NGC 7142 NGC 7429 NGC 2300 NGC 7160 NGC 7510 NGC 6939 NGC 7226 NGC 7538 NGC 6949 NGC 7235 NGC 7708 NGC 6951 NGC 7261 NGC 7762 NGC 7023 NGC 7281 NGC 7822 Sternbild- Übersicht Zur Objektauswahl: Nummer anklicken Zur Übersichtskarte: Objekt anklicken Sternbildübersicht Auswahl NGC 40_7708 Aufsuchkarte Auswahl NGC 188_Aufsuchkarte 2 UMi 2 Auswahl NGC 1184 Aufsuchkarte Auswahl NGC 1544_2276_2300 Aufsuchkarte Auswahl NGC 6939 Aufsuchkarte Auswahl NGC 6949_6951 Aufsuchkarte Auswahl NGC 7023 Aufsuchkarte Auswahl NGC 7055 Aufsuchkarte Auswahl NGC 7076 Aufsuchkarte Auswahl NGC 7129_7142 Aufsuchkarte Auswahl NGC 7139_7160 Aufsuchkarte Auswahl NGC 7226_7235 Aufsuchkarte Auswahl N 7261_7281 Aufsuchkarte Auswahl NGC 7354_7419_7429_7510_7538 Aufsuchkarte Auswahl NGC 7380_7423 Aufsuchkarte Auswahl NGC 7762_7822 Aufsuchkarte Auswahl NGC 40 Übersichtskarte Aufsuch- Auswahl karte NGC 188 Übersichtskarte Aufsuch- Auswahl karte NGC 1184 Übersichtskarte Aufsuch- Auswahl karte NGC 1544 Übersichtskarte Aufsuch- Auswahl karte N 2276_N 2300 Übersichtskarte Aufsuch- Auswahl karte NGC 6939 Übersichtskarte Aufsuch- Auswahl karte NGC 6949 Übersichtskarte Aufsuch- Auswahl karte NGC 6951 Übersichtskarte Aufsuch- Auswahl karte NGC 7023 Übersichtskarte Aufsuch- Auswahl karte NGC 7055 Übersichtskarte Aufsuch- Auswahl karte NGC 7076 Übersichtskarte Aufsuch- Auswahl karte NGC 7129_7142 Übersichtskarte Aufsuch- Auswahl karte NGC 7139
    [Show full text]
  • A Blast Wave from the 1843 Eruption of Eta Carinae
    1 A Blast Wave from the 1843 Eruption of Eta Carinae Nathan Smith* *Astronomy Department, University of California, 601 Campbell Hall, Berkeley, CA 94720-3411 Very massive stars shed much of their mass in violent precursor eruptions [1] as luminous blue variables (LBVs) [2] before reaching their most likely end as supernovae, but the cause of LBV eruptions is unknown. The 19th century eruption of Eta Carinae, the prototype of these events [3], ejected about 12 solar masses at speeds of 650 km/s, with a kinetic energy of almost 1050ergs[4]. Some faster material with speeds up to 1000-2000 km/s had previously been reported [5,6,7,8] but its full distribution was unknown. Here I report observations of much faster material with speeds up to 3500-6000 km/s, reaching farther from the star than the fastest material in earlier reports [5]. This fast material roughly doubles the kinetic energy of the 19th century event, and suggests that it released a blast wave now propagating ahead of the massive ejecta. Thus, Eta Carinae’s outer shell now mimics a low-energy supernova remnant. The eruption has usually been discussed in terms of an extreme wind driven by the star’s luminosity [2,3,9,10], but fast material reported here suggests that it was powered by a deep-seated explosion rivalling a supernova, perhaps triggered by the pulsational pair instability[11]. This may alter interpretations of similar events seen in other galaxies. Eta Carinae [3] is the most luminous and the best studied among LBVs [1,2].
    [Show full text]
  • Observing Dust Grain Growth and Sedimentation in Circumstellar Discs Interpretations and Predictions of Their Observable Quantities in a Multi-Wavelength Approach
    Observing dust grain growth and sedimentation in circumstellar discs Interpretations and predictions of their observable quantities in a multi-wavelength approach Dissertation zur Erlangung des Doktorgrades der Mathematisch-Naturwissenschaftliche Fakult¨at der Christian-Albrechts Universit¨atzu Kiel vorgelegt von J¨urgenSauter Kiel, 2011 Referent : Prof. Dr. S. Wolf Koreferent: Prof. Dr. C. Dullemond Tag der m¨undlichen Pr¨ufung: 7. Juli 2011 Zum Druck genehmigt: 7. Juli 2011 gez. Prof. Dr. L. Kipp, Dekan To my growing family Abstract In the present thesis, the observational effects of dust grain growth and sedimentation in circumstellar discs are investigated. The growth of dust grains from some nanometres in diameter as found in the inter- stellar medium towards planetesimal bodies some meters in diameter is an important step in the formation of planets. However, this process is currently not entirely un- derstood. Especially, in the literature several `barriers' are discussed that apparently prohibit an effective growth of dust grains. Hence, it is of particular interest to compare theories and observational data in this respect. State-of-the-art radiative transfer techniques allow one to derive observable quantities from theoretical models that allow this comparison. In this thesis, generic tracers of dust grain growth in spatially high resolution multi-wavelength images are identified for the first time. Further, a possibility to detect a dust trapping mechanism for dust grains by local pressure maxima using the new interferometer, ALMA, is established. By fitting parametric models to new observations of the disc in the Bok globule CB 26, unexpected features of the system are revealed, such as a large inner void and the possibility to interpret the data without the need for grain growth.
    [Show full text]