Presentation on theme: "R.S. RAM, K. TERESZCHUK, I. GORDON 1, K.A. WALKER 2 and P. F. BERNATH Department of Chemistry, University of York, Heslington, York YO10 5DD, UK. 1 Harvard-Smithsonian."— Presentation transcript:
R.S. RAM, K. TERESZCHUK, I. GORDON 1, K.A. WALKER 2 and P. F. BERNATH Department of Chemistry, University of York, Heslington, York YO10 5DD, UK. 1 Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138, USA. 2 Department of Physics, University of Toronto, Toronto, Ont., M5S 1A7, Canada.
INTRODUCTION CaH is known since almost a century [e.g. A 2 Π-X 2 Σ +, B 2 Σ + -X 2 Σ + transitions] CaH is an important astrophysical molecule Sunspots [Olmsted(1908)] M-type stars [Öhman (1934)], L-dwarfs [Burgasser et al. (2007)] CaH is an important opacity source in brown dwarfs Luminosity indicator for cool stars
L- Dwarf Spectra T=1800 K T=1600 K T=1400 K As the temperature drops metal oxides disappear and metal hydrides start appearing CrH 0-0 A 6 Σ-X 6 Σ FeH 1-0 F 4 Δ-X 4 Δ CaH 0-0 A 2 Π-X 2 Σ + Hydride bands are used to identify M- and L-dwarfs Kirkpatrick et al. ApJ 519, 802 (1999)
Previous work on CaH Diode laser measurements [Petitprez et al. 1989] FTS measurements [Frum & Pickett (1993), Shayesteh et al. (2004)] LIF & Molecular beam source: [Steimle et al. (2004), (2006), (2008)] Theoretical studies [Honjou et al. (1981), Chamnaud & Levy (1989) Leininger and Jeung (1995), Weck et al. (2003)] A 2 Π-X 2 Σ +, B 2 Σ + -X 2 Σ + transitions [Berg et al. (1974)-(1976)] E 2 Π-X 2 Σ + transition [Grundström (1932), Watson & Weber (1935)] Present work High resolution study of the E 2 Π-X 2 Σ + transition of CaH and CaD Rotational analysis of the 0-0 and 1-1 bands
6σ 2 7σX2Σ+X2Σ+ 6σ 2 3πA2ΠA2Π 6σ 2 8σB2Σ+B2Σ+ 6σ24π6σ24πE2ΠE2Π 6σ7σ26σ7σ2 D2Σ+D2Σ+ Honjou et al. (1981) LOW-LYING ELECTRONIC STATES
E 2 Π-X 2 Σ + SYSTEM OF SrH AND SrD Electronic spectroscopy Watson & Friedrikson (1932), Friedrikson et al. (1935), (1936) [Observed low-lying electronic states, A 2 Π, B 2 Σ +, E 2 Π, D 2 Σ +, C 2 Σ + ] Higher-lying electronic states: Khan et al. (1963)-(1981) Rotational analysis: A 2 Π-X 2 Σ + & B 2 Σ + -X 2 Σ + transitions [Appelblad et al. (1986)] Infrared Spectroscopy Magg et al. (1988), Birk et al. (1989) Frum et al. (1994), Shayesteh et al. (2004) Present work Rotational analysis of the 0-0 and 1-1 bands of the E 2 Π-X 2 Σ + transition
SUMMARY High resolution analysis: E-X transition of CaH, CaD and SrH, SrD Rotational analysis of the 0-0 and 1-1 bands have been obtained Perturbations have been observed in the E 2 Π state The E 2 Π interacts with a close-lying 2 Σ + state or the higher vibrational levels of the B 2 Σ + state Calculation of extended line list, Einstein A-coefficients and absolute line intensities of the E 2 Π-X 2 Σ + transition of CaH using PGOPHER is in progress Work in progress