2010A&A...518A..48F


Query : 2010A&A...518A..48F

2010A&A...518A..48F - Astronomy and Astrophysics, volume 518, A48-48 (2010/7-2)

Photospheric and chromospheric activity on the young solar-type star HD 171488 (V889 herculis).

FRASCA A., BIAZZO K., KOVARI Zs., MARILLI E. and CAKIRLI O.

Abstract (from CDS):

We present the results of contemporaneous spectroscopic and photometric monitoring of the young solar-type star HD 171488 (Prot≃1.337 days) aimed at studying surface inhomogeneities at both photospheric and chromospheric levels. Echelle FOCES spectra (R≃40000) and Johnson BV photometry have been performed in August 2006, with a good coverage of rotational phases. Spectral type, rotational velocity, metalicity, and gravity were determined with a code developed by us (Rotfit) and a library of high-resolution spectra of slowly-rotating reference stars. The metalicity was measured from the analysis of iron lines with the Moog code. The spectral subtraction technique was applied to the most relevant chromospheric diagnostics included in the FOCES spectral range, namely CaII IRT, Hα, HeID3, Hβ, and CaII H&K lines. A simple model with two large high-latitude spots is sufficient to reproduce the B and V light curves as well as the radial velocity modulation if a temperature difference between photosphere and spots of about 1500K is used. A Doppler-imaging analysis of photospheric lines basically confirms a similar spot distribution. With the help of an analogous geometric two-spot model, we are able to reproduce the observed modulations in the residual chromospheric emissions adopting different values of ratios between the flux of plages and the quiet chromosphere (about 5 for Hα and 3 for CaII diagnostics). Facular regions of solar type appear to be the main responsible features for the modulations of chromospheric diagnostics. Both the spot/plage model and the cross-correlation between the light curve and the chromospheric line fluxes display a significant lead effect of plages with respect to spots (from 20° to 40° in longitude), as already observed in some active solar-type stars and RS CVn systems. The contemporaneous monitoring of photospheric and chromospheric diagnostics in the young and rapidly rotating solar-type star HD 171488 allowed us to detect active regions which have nearly the same location at both atmospheric layers, with plages slightly leading spots in longitudes. These active regions are similar to the solar ones in some respects, because the spot temperature is close to that of sunspot umbrae and the plage flux-contrast is consistent with the average solar values. The main differences with respect to the Sun are larger sizes and higher latitudes.

Abstract Copyright:

Journal keyword(s): stars: activity - starspots - stars: chromospheres - stars: rotation - stars: individual: HD 171488

Simbad objects: 15

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Number of rows : 15
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 * alf Ari PM* 02 07 10.40570 +23 27 44.7032 4.29 3.17 2.01 1.15 0.54 K2-IIIbCa-1 615 1
2 * 10 Tau PM* 03 36 52.3837044168 +00 24 05.992097829 5.23 5.15 4.30 4.09 3.77 F9IV-V 542 0
3 Cl Melotte 22 OpC 03 46 24 +24 06.8           ~ 3195 0
4 HD 27406 BY* 04 20 12.9666179232 +19 14 00.518450172   8.016 7.444 7.131 6.826 F9V+ 183 0
5 * w Her RG* 17 20 39.5674498400 +32 28 03.877958860 6.08 6.01 5.39 4.89 4.56 G0V 435 0
6 HD 171286 PM* 18 33 14.6555926560 +18 54 55.997031240 8.800 7.900 6.840     K0 19 0
7 V* V889 Her BY* 18 34 20.1028767504 +18 41 24.234675864   8.00 7.449   6.720 G2V 129 0
8 HD 348931 PM* 18 34 26.2896639864 +17 44 02.026737240   8.97 8.41     F8 3 0
9 HD 171623 ** 18 35 12.5919974496 +18 12 12.293953884 5.670 5.780 5.790     A0Vn 48 0
10 HD 171448 * 18 36 20.3082694944 -32 18 00.550542852   10.44 10.13     A3 4 0
11 * omi Aql PM* 19 51 01.6436960928 +10 24 56.592457524   5.66   4.8   F8V 439 0
12 * alf Cep PM* 21 18 34.77233 +62 35 08.0681 2.770 2.680 2.460 2.22 2.11 A8Vn 347 0
13 V* HN Peg BY* 21 44 31.3299461136 +14 46 18.983292600       6.16   G0V+ 479 0
14 V* V383 Lac BY* 22 20 07.0254050808 +49 30 11.767337496   9.42 8.58     K1V 75 0
15 NAME Pleiades Moving Group MGr ~ ~           ~ 264 1

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2022.06.28-23:23:41

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