Starspots and active regions on the emission red dwarf star $LQ~Hydrae$

Alekseev, I. Yu.; Козлова, О. В.

doi:10.1051/0004-6361:20021424

Cited by 18 publications

(12 citation statements)

References 34 publications

(49 reference statements)

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…In previous papers (Alekseev & Kozlova 2000, 2002 we noted that the active regions (plages) for the chromospherically active binaries V775 Her and VY Ari, and for the active single star LQ Hya are concentrated near the most spotted longitude. We present in Figs In 2000 we obtained four observational points.…”

Section: The Starspots -Active Regions Connectionmentioning

confidence: 85%

“…MS Ser was observed regularly during 1991, 1994-2002. During 1998 there were a few measurements only.…”

Section: Photometrymentioning

confidence: 99%

“…In our previous papers we obtained complex information about active regions on surfaces of some chromospherically active variables: V775 Her (Alekseev & Kozlova 2000), VY Ari (Alekseev & Kozlova 2001), and LQ Hya (Alekseev & Kozlova 2002). In these papers we carried out the uniform constructions of spottedness models for program stars on the basis of the total set of published and original photometric observations.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Starspots and active regions on the chromospherically active binary MS Ser

Alekseev

Козлова

2003

A&A

Self Cite

View full text Add to dashboard Cite

Abstract. The quasisimultaneous electrophotometric, polarimetric and spectroscopic observations of the chromospherically active binary MS Ser are presented. The photometric variability of the star can be described completely by a zonal spottedness model. Spotted regions occupy up to 21% of the total stellar surface. The temperature difference between the unspotted photosphere and starspots is about 1300 K. Starspots are localized at the middle latitudes. We detected the broad-band linear polarization of the stellar light and its rotational modulation connected with the local magnetic region on the stellar surface. We suspect that there is a space connection between plages, magnetic regions and the mostly spotted stellar longitudes.

show abstract

Section: The Starspots -Active Regions Connectionmentioning

confidence: 85%

“…MS Ser was observed regularly during 1991, 1994-2002. During 1998 there were a few measurements only.…”

Section: Photometrymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Starspots and active regions on the chromospherically active binary MS Ser

Alekseev

Козлова

2003

A&A

Self Cite

View full text Add to dashboard Cite

show abstract

“…No rotational modulation of EW Hα emerges over the data scatter. This result may be surprising, because rotational modulation of the Hα emission frequently has been detected in several highly-and mildly-active stars (see, e.g., Frasca et al 2000Frasca et al , 2008bAlekseev & Kozlova 2002, 2003Biazzo et al 2006Biazzo et al , 2007b. However, in some cases, no clear rotational modulation of chromospheric diagnostics has been detected despite the contemporaneous wave-like behaviour in the photometry (see, e.g., Catalano et al 2000).…”

Section: Hα Linementioning

confidence: 98%

The young active star SAO 51891 (V383 Lacertae)

Biazzo

Frasca

Marilli

et al. 2009

A&A

View full text Add to dashboard Cite

Aims. The aim of this work is to investigate the surface inhomogeneities of a young, late-type star, SAO 51891, at different atmospheric levels, from the photosphere to the upper chromosphere, analyzing contemporaneous optical high-resolution spectra and broad-band photometry. Methods. The full spectral range of FOCES@CAHA (R 40 000) is used to perform the spectral classification and to determine the rotational and radial velocities. The lithium abundance is measured to obtain an age estimate. The BVRIJHK s photometric bands are used to construct the spectral energy distribution (SED). The variations in the observed BV fluxes and effective temperature are used to infer the presence of photospheric spots and observe their behavior over time. The chromospheric activity is studied applying the spectral subtraction technique to Hα, Ca ii H & K, H , and Ca ii IRT lines.Results. We find SAO 51891 to be a young K0-1V star with a lithium abundance close to the Pleiades upper envelope, confirming its youth (∼100 Myr), which is also inferred from its kinematical membership of the Local Association. No infrared excess is detected from analysis of its SED, limiting the amount of remaining circumstellar dust. We detect a rotational modulation of the luminosity, effective temperature, Ca ii H & K, H , and Ca ii IRT total fluxes. A simple spot model with two main active regions, about 240 K cooler than the surrounding photosphere, fits the observed light and temperature curves very well. The small-amplitude radial velocity variations are also well reproduced by our spot model. The anti-correlation of light curves and chromospheric diagnostics indicates chromospheric plages spatially associated with the spots. The largest modulation amplitude is observed for the H flux suggesting that this line is very sensitive to the presence of chromospheric plages. Conclusions. SAO 51891 is a young active star, lacking significant amounts of circumstellar dust or any evidence of low mass companions, and displays the typical phenomena produced by magnetic activity. The spots are larger and warmer than those in less active main-sequence stars. If some debris is still present around the star, it will only be detectable by future far-infrared and sub-mm observations (e.g., Herschel or ALMA). The RV variation produced by the starspots has an amplitude comparable with those induced by Jupiter-mass planets orbiting close to the host star. SAO 51891 is another good example of an active star in which the detection of planets may be hampered by the high activity level.

show abstract

“…Some active stars also show evidence for correlated magnetic activity in the photosphere and chromosphere. Alekseev & Kozlova (2002) investigated quasi-simultaneous photometric observations, photo-polarimetry and high-resolution spectra of a young solar-like star LQ Hya. They found evidence for a connection between plages, magnetic regions and the starspot longitudes.…”

Section: Correlating Activity In the Photosphere And Chromospherementioning

confidence: 99%

Photospheric and chromospheric activity on EY Dra

Korhonen¹,

Brogaard

Holhjem

et al. 2007

Astron Nachr

View full text Add to dashboard Cite

Magnetic activity in the photosphere and chromosphere of the M dwarf EY Dra is studied and possible correlations between the two are investigated using photometric observations in the V and R bands and optical and near infrared spectroscopy. The longitudinal spot configuration in the photosphere is obtained from the V band photometry, and the chromospheric structures are investigated using variations in the Hα line profile and observations of the Paschen β line. The shape of the V band light-curve indicates two active regions on the stellar surface, about 0.4 in phase apart. The spectroscopic observations show enhanced Hα emission observed close to the phases of the photometrically detected starspots. This could indicate chromospheric plages associated with the photospheric starspots. Some indications of prominence structures are also seen. The chromospheric pressure is limited to log mTR < −4 based on the non-detection of emission in the Paschen β wavelength region.

show abstract

Starspots and active regions on the emission red dwarf star $LQ~Hydrae$

Cited by 18 publications

References 34 publications

Starspots and active regions on the chromospherically active binary MS Ser

Starspots and active regions on the chromospherically active binary MS Ser

The young active star SAO 51891 (V383 Lacertae)

Photospheric and chromospheric activity on EY Dra

Contact Info

Product

Resources

About