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HD 41473


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관련 글

Discovery of the Coolest Extreme Subdwarf
We report the discovery of LEHPM 2-59 as the coolest extreme M subdwarf(esdM) found to date. Optical and near-infrared spectroscopy demonstratethat this source is of later spectral type than the esdM7 APMPMJ0559-2903, with the presence of strong alkali lines (including Rb I),VO absorption at 7400 Å, and H2O absorption at 1.4μm. Current optical classification schemes yield a spectral type ofesdM8, making LEHPM 2-59 one of only two ultracool esdMs known. Thesubstantial space velocity of this object (Vgalactic~-180 kms-1) identifies it as a halo star. Spectral model fits to theoptical and near-infrared spectral data for this and four otherlate-type esdMs indicate that LEHPM 2-59 is the coolest esdM currentlyknown, with Teff=2800-3000 K and -1.5<~[M/H]<~-2.0.Comparison of Teff determinations for M dwarfs and esdMsbased on spectral model fits from this study and the literaturedemonstrate a divergence in Teff scales beyond spectral types~M5/esdM5, as large as 600-800 K by types M8/esdM8. While thisdivergence is likely an artifact of the underlying classificationscheme, it may lead to systematic errors in the derived properties ofintermediate metallicity subdwarfs. We comment on the future ofultracool subdwarf classification and suggest several ideas foraddressing shortcomings in current (largely extrapolated) schemes.

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관측 및 측정 데이터

별자리:비둘기자리
적경:06h04m07.22s
적위:-29°20'20.5"
가시등급:7.792
거리:332.226 파섹
적경상의 고유운동:-6.8
적위상의 고유운동:-0.8
B-T magnitude:7.761
V-T magnitude:7.79

천체목록:
일반명   (Edit)
HD 1989HD 41473
TYCHO-2 2000TYC 6504-815-1
USNO-A2.0USNO-A2 0600-02917278
HIPHIP 28735

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