1997A&A...323..909F


Query : 1997A&A...323..909F

1997A&A...323..909F - Astronomy and Astrophysics, volume 323, 909-922 (1997/7-3)

The surface gravities of cool dwarf stars revisited.

FUHRMANN K., PFEIFFER M., FRANK C., REETZ J. and GEHREN T.

Abstract (from CDS):

On the base of high-resolution spectra and standard model atmosphere analyses we propose to employ the pressure-broadened Mg Ib lines to derive the gravity parameter for F and G stars. These lines are advocated to be a much more robust and reliable tracer compared to the ionization equilibrium of, say, Fe I/Fe II, which is susceptible to overionization effects and uncertainties in the temperature structure of the model atmosphere. It is demonstrated that the strong line method circumvents the long-standing discrepancy ({DELTA}logg∼0.5dex) of the standard F star Procyon, the surface gravity of which is precisely known due to its nearness and binary nature. We also discuss similar effects on other, predominantly metal-poor stars. In fact, many of the F and hotter G stars deviate in the LTE metal abundances of neutral and ionized species by up to 0.2dex. However, once the surface gravity parameter is fixed, very reliable iron abundances from Fe II can be derived as well. As a consequence a number of stars considered to be standards will require revised stellar parameters in future analyses. This will have some impact on stellar distances, ages, and galactic evolution in particular.

Abstract Copyright:

Journal keyword(s): techniques: spectroscopic - stars: fundamental parameters - stars: individual: Procyon - stars: late-type - stars: subdwarfs - Galaxy: evolution

Simbad objects: 8

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Number of rows : 8
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2022
#notes
1 HD 400 PM* 00 08 40.9385785968 +36 37 37.652234016       5.9   F8IV 158 0
2 HD 19445 PM* 03 08 25.5883873084 +26 19 51.400965175 8.29 8.52 8.06 7.60 7.27 G2VFe-3 752 0
3 HD 30743 PM* 04 49 42.2441132544 -13 46 10.807837356   6.70 6.26     F6VFe-0.9CH-0.5 124 0
4 * alf CMi SB* 07 39 18.11950 +05 13 29.9552 0.82 0.79 0.37 -0.05 -0.28 F5IV-V+DQZ 1818 0
5 HD 140283 Pe* 15 43 03.0971190219 -10 56 00.595693188 7.508 7.711 7.212 6.63 8.21 F9VkA5mA1 890 0
6 * omi Aql PM* 19 51 01.6436960928 +10 24 56.592457524   5.66   4.8   F8V 438 0
7 HD 194598 PM* 20 26 11.9183775668 +09 27 00.429558608 8.62 8.82 8.34 7.90 7.56 F8 293 0
8 HD 201891 PM* 21 11 59.0321495469 +17 43 39.890919730 7.74 7.88 7.37 6.91 6.59 G5V_Fe-2.5 377 0

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2022.05.19-21:17:52

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