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Not Surprising That the Method Begins to Break Down at This Point
152 ASTRONOMY: W. S. ADAMS hanced lines in the early F stars are normally so prominent that it is not surprising that the method begins to break down at this point. To illustrate the use of the formulae and curves we may select as il- lustrations a few stars of different spectral types and magnitudes. These are collected in Table II. The classification is from Mount Wilson determinations. TABLE H ~A M PARAIuAX srTATYP_________________ (a) I(b) (C) (a) (b) c) Mean Comp. Ob. Pi 10U96.... 7.6F5 -0.7 +0.7 +3.0 +6.5 4.7 5.8 5.7 +0#04 +0.04 Sun........ GO -0.5 +0.5 +3.0 +5.6 4.3 5.8 5.2 Lal. 38287.. 7.2 G5 -1.8 +1.5 +3.5 +7.4 +6.3 +6.2 7.3 +0.10 +0.09 a Arietis... 2.2K0O +2.5 -2.4 +0.2 +1.0 1.3 +0.2 0.8 +0.05 +0.09 aTauri.... 1.1K5 +3.0 -2.0 +0.5 -0.4 +1.9 +0.5 0.7 +0.08 +0.07 61' Cygni...6.3K8 -1.8 +5.8 +7.7 +8.2 9.3 8.9 8.8 +0.32 +0.31 Groom. 34..8.2 Ma -2.2 +6.8 +9.2 +10.2 10.5 10.4 10.4 +0.28 +0.28 The parallaxes are computed from the absolute magnitudes by the formula, to which reference has already been made, 5 logr = M - m - 5. The results are given in the next to the last column of the table, and the measured parallaxes in the final column. -
Downloads/ Astero2007.Pdf) and by Aerts Et Al (2010)
This work is protected by copyright and other intellectual property rights and duplication or sale of all or part is not permitted, except that material may be duplicated by you for research, private study, criticism/review or educational purposes. Electronic or print copies are for your own personal, non- commercial use and shall not be passed to any other individual. No quotation may be published without proper acknowledgement. For any other use, or to quote extensively from the work, permission must be obtained from the copyright holder/s. i Fundamental Properties of Solar-Type Eclipsing Binary Stars, and Kinematic Biases of Exoplanet Host Stars Richard J. Hutcheon Submitted in accordance with the requirements for the degree of Doctor of Philosophy. Research Institute: School of Environmental and Physical Sciences and Applied Mathematics. University of Keele June 2015 ii iii Abstract This thesis is in three parts: 1) a kinematical study of exoplanet host stars, 2) a study of the detached eclipsing binary V1094 Tau and 3) and observations of other eclipsing binaries. Part I investigates kinematical biases between two methods of detecting exoplanets; the ground based transit and radial velocity methods. Distances of the host stars from each method lie in almost non-overlapping groups. Samples of host stars from each group are selected. They are compared by means of matching comparison samples of stars not known to have exoplanets. The detection methods are found to introduce a negligible bias into the metallicities of the host stars but the ground based transit method introduces a median age bias of about -2 Gyr. -
Arxiv:0706.2206V1 [Astro-Ph] 14 Jun 2007 1983; Beichman Et Al
Accepted to the Astrophysical Journal Supplemental Series Preprint typeset using LATEX style emulateapj v. 08/22/09 A CASE STUDY OF LOW-MASS STAR FORMATION Jonathan J. Swift Institute for Astronomy, 2680 Woodlawn Dr., Honolulu, HI 96822-1897: [email protected] William J. Welch Department of Astronomy and Radio Astronomy Laboratory, University of California, 601 Campbell Hall, Berkeley, CA 94720-3411 Accepted to the Astrophysical Journal Supplemental Series ABSTRACT This article synthesizes observational data from an extensive program aimed toward a comprehensive understanding of star formation in a low-mass star-forming molecular cloud. New observations and published data spanning from the centimeter wave band to the near infrared reveal the high and low density molecular gas, dust, and pre-main sequence stars in L1551. The total cloud mass of ∼ 160 M contained within a 0.9 pc has a dynamical timescale, tdyn = 1:1 Myr. Thirty-five pre-main sequence stars with masses from ∼ 0:1 to 1.5 M are selected to be members of the L1551 association constituting a total of 22 ± 5 M of stellar mass. The observed star formation efficiency, SFE = 12%, while the total efficiency, SFEtot, is estimated to fall between 9 and 15%. L1551 appears to have been forming stars for several tdyn with the rate of star formation increas- ing with time. Star formation has likely progressed from east to west, and there is clear evidence that another star or stellar system will form in the high column density region to the northwest of L1551 IRS5. High-resolution, wide-field maps of L1551 in CO isotopologue emission display the structure of the molecular cloud at 1600 AU physical resolution. -
Lecture 26 Pre-Main Sequence Evolution
Lecture 26 Low-Mass Young Stellar Objects 1. Nearby Star Formation 2. General Properties of Young Stars 3. T Tauri Stars 4. Herbig Ae/Be Stars References Adams, Lizano & Shu ARAA 25 231987 Lada OSPS 1999 Stahler & Palla Chs. 17 & 18 Local Star Forming Regions Much of our knowledge of star formation comes from a few nearby regions Taurus-Auriga & Perseus – 150 pc low mass (sun-like) stars Orion – 450 pc high & low mass stars [Grey – Milky Way Black – Molecular clouds] Representative for the Galaxy as a whole? Stahler & Palla Fig 1.1 PERSEUS with famous objects AURIGA NGC 1579 B5 IC 348 NGC 1333 TMC-1 T Tau L1551 TAURUS Taurus, Auriga & Perseus • A cloud complex rich in cores & YSOs • NGC1333/IC 348 • Pleiades •TMC-1,2 • T Tauri & other TTSs • L 1551 Ophiuchus Wilking et al. 1987 AJ 94 106 CO Andre PP IV Orion L1630 L1630 star clusters L1630 in Orion NIR star clusters on CS(2-1) map E Lada, ApJ 393 25 1992 4 M(L1630) ~ 8x10 Msun 5 massive cores (~ 200 Msun) associated with NIR star clusters 2. General Properties Young stars are associated with molecular clouds. Observations are affected by extinction, which decreases with increasing wavelength. Loosely speaking, we can distinguish two types: Embedded stars - seen only at NIR or longer wavelengths, usually presumed to be very young Revealed stars - seen at optical wavelengths or shorter, usually presumed to be older What makes young stars particularly interesting is Circumstellar gas and dust – both flowing in as well as out, e.g., jets, winds, & disks. -
Ephemerides Astronomicae. Anni...Ad Meridianum Mediolanensem
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A&A 397, 693–710 (2003) Astronomy DOI: 10.1051/0004-6361:20021545 & c ESO 2003 Astrophysics Near-IR echelle spectroscopy of Class I protostars: Mapping Forbidden Emission-Line (FEL) regions in [FeII] C. J. Davis1,E.Whelan2,T.P.Ray2, and A. Chrysostomou3 1 Joint Astronomy Centre, 660 North A’oh¯ok¯u Place, University Park, Hilo, Hawaii 96720, USA 2 Dublin Institute for Advanced Studies, School of Cosmic Physics, 5 Merrion Square, Dublin 2, Ireland 3 Department of Physical Sciences, University of Hertfordshire, Hatfield, Herts AL10 9AB, UK Received 27 August 2002 / Accepted 22 October 2002 Abstract. Near-IR echelle spectra in [FeII] 1.644 µm emission trace Forbidden Emission Line (FEL) regions towards seven Class I HH energy sources (SVS 13, B5-IRS1, IRAS 04239+2436, L1551-IRS5, HH 34-IRS, HH 72-IRS and HH 379-IRS) and three classical T Tauri stars (AS 353A, DG Tau and RW Aur). The parameters of these FEL regions are compared to the characteristics of the Molecular Hydrogen Emission Line (MHEL) regions recently discovered towards the same outflow sources (Davis et al. 2001 – Paper I). The [FeII] and H2 lines both trace emission from the base of a large-scale collimated outflow, although they clearly trace different flow components. We find that the [FeII] is associated with higher-velocity gas than the H2, and that the [FeII] emission peaks further away from the embedded source in each system. This is probably because the [FeII] is more closely associated with HH-type shocks in the inner, on-axis jet regions, while the H2 may be excited along the boundary between the jet and the near-stationary, dense ambient medium that envelopes the protostar. -