Chromospheric activity in several single late-type stars

Zhang, Liyun; Pi, Qingfeng; Zhu, Zong-Hong

doi:10.1088/1674-4527/15/2/009

Cited by 13 publications

(16 citation statements)

References 88 publications

(148 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Chromospherically active stars and their properties have been studied previously by many authors (Strassmeier et al 1990(Strassmeier et al , 1993Doyle et al 1994;Fekel et al 2005;Montes et al 2004;Hall 2008;Biazzo et al 2009;Frasca et al 2010;Cao & Gu 2015;Zhang et al 2015;etc). The spectral subtraction technique has been widely applied to different chromospheric activity indicators (Barden 1985;Montes et al 2004;Zhang et al 2015;etc).…”

Section: Introductionmentioning

confidence: 98%

Chromospheric activity on late-type star DM UMa using high-resolution spectroscopic observations

Zhang

Han

et al. 2016

Mon. Not. R. Astron. Soc.

View full text Add to dashboard Cite

We present new 14 high-resolution echelle spectra to discuss the level of chromospheric activity of DM UMa in He i D 3 , Na i D 1 , D 2 , H α , and Ca ii infrared triplet lines (IRT). It is the first time to discover the emissions above the continuum in the He i D 3 lines on Feb. 9 and 10, 2015. The emission on Feb. 9 is the strongest one ever detected for DM UMa. We analyzed these chromospheric active indicators by employing the spectral subtraction technique. The subtracted spectra reveal weak emissions in the Na i D 1 , D 2 lines, strong emission in the H α line, and clear excess emissions in the Ca ii IRT lines. Our values for the EW 8542 /EW 8498 ratio are on the low side, in the range of 1.0 -1.7. There are also clear phase variations of the level of chromospheric activity in equivalent width (EW) light curves in these chromospheric active lines (especially the H α line). These phenomena might be explained by flare events or rotational modulations of the level of chromospheric activity.

show abstract

Section: Introductionmentioning

confidence: 98%

Chromospheric activity on late-type star DM UMa using high-resolution spectroscopic observations

Zhang

Han

et al. 2016

Mon. Not. R. Astron. Soc.

View full text Add to dashboard Cite

show abstract

“…Optical wavelength observations in previous researches also show that the intensities of Hα and Hβ are enhanced during the flares of EV Lac (Melikian et al, 2006;Honda et al, 2018). The enhancements of the Balmer lines indicate that the chromospheric activities of the flare stars occur in the middle chromosphere (Montes et al, 2000;Zhang, 2011;Zhang et al, 2015). In addition to the Balmer lines, several studies have shown that Ca II H & K, Na I D and He I lines also exhibit enhanced radiation during flares (Lalitha et al, 2013;Kowalski et al, 2013Kowalski et al, , 2016.…”

Section: Discussionmentioning

confidence: 91%

Photometric and Spectroscopic Study of Flares on Ross 15

Bai,

Esamdin,

Gao

et al. 2020

Preprint

View full text Add to dashboard Cite

We conducted photometric and spectroscopic observations for Ross 15 in order to further study the flare properties of this less observed flare star. A total of 28 B-band flares are detected in 128 hours of photometric observations, leading to a total flare rate of 0.22 +0.04 −0.04 hour −1 , more accurate than that provided by previous work. We give the energy range of the B-band flare (10 29.5 -10 31.5 erg) and the FFD for the star. Within the same energy range, the FFD are lower than that of GJ 1243 (M4) and YZ CMi (M4.5), roughly in the middle of those of three M5-type stars and higher than the average FFDs of spectral types ≥ M6. We performed, for the first time to Ross 15, simultaneous highcadence spectroscopic and photometric observations, resulting in detection of the most energetic flare in our sample. The intensity enhancements of the continuum and Balmer lines with significant correlations between them are detected during the flare, which is same with that of the other deeply studied flare stars of the similar spectral type.

show abstract

“…They found EW 8542 /EW 8498 ratios of 1.0-1.7, which implies the presence of optically thick plages. This is typical of many late-type stars [111,[122][123][124][125][126]. The infrared triplet lines are formed in the lower chromosphere through subordinate transitions between the excited levels of Ca II 4 2 P 1/2,2/3 and meta-stable 3 2 D 3/2,5/2 [127,128].…”

Section: Spectroscopic Diagnosticsmentioning

confidence: 98%

“…Magnetic activity is also evidenced, in some cases, in the form of X-ray variability associated with magnetised coronae [266], transition region emission or flares at optical, X-ray, UV and radio wavelengths [113,126,163,266,[273][274][275]. Note that the photometric and spectroscopic characteristics of FK Comae stars closely resemble those of RS CVn stars, although the former are single, rapidly rotating giant stars that do not show any evidence of multiplicity.…”

Section: Rs Canum Venaticorum Systemsmentioning

confidence: 99%

Stellar Chromospheric Variability

Grijs

Kamath

2021

Universe

View full text Add to dashboard Cite

Cool stars with convective envelopes of spectral types F and later tend to exhibit magnetic activity throughout their atmospheres. The presence of strong and variable magnetic fields is evidenced by photospheric starspots, chromospheric plages and coronal flares, as well as by strong Ca ii H+K and Hα emission, combined with the presence of ultraviolet resonance lines. We review the drivers of stellar chromospheric activity and the resulting physical parameters implied by the observational diagnostics. At a basic level, we explore the importance of stellar dynamos and their activity cycles for a range of stellar types across the Hertzsprung–Russell diagram. We focus, in particular, on recent developments pertaining to stellar rotation properties, including the putative Vaughan–Preston gap. We also pay specific attention to magnetic variability associated with close binary systems, including RS Canum Venaticorum, BY Draconis, W Ursae Majoris and Algol binaries. At the present time, large-scale photometric and spectroscopic surveys are becoming generally available, thus leading to a resurgence of research into chromospheric activity. This opens up promising prospects to gain a much improved understanding of chromospheric physics and its wide-ranging impact.

show abstract

Chromospheric activity in several single late-type stars

Cited by 13 publications

References 88 publications

Chromospheric activity on late-type star DM UMa using high-resolution spectroscopic observations

Chromospheric activity on late-type star DM UMa using high-resolution spectroscopic observations

Photometric and Spectroscopic Study of Flares on Ross 15

Stellar Chromospheric Variability

Contact Info

Product

Resources

About