LU Vel (GJ 375): A M3.5Ve Flare and Double-Lined Spectroscopic Binary

Montes, D.; Gálvez, M. C.; Fernández-Figueroa, M. J.; Crespo‐Chacón, I.

doi:10.1007/s10509-006-9163-3

Cited by 6 publications

(9 citation statements)

References 2 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…We have recently become aware of the work by Montes et al (2006), who derive orbital parameters for this system in good agreement with the ones presented in this work.…”

Section: Discussionsupporting

confidence: 81%

The spectroscopic binary system Gl 375

Díaz¹,

González

Cincunegui³

et al. 2007

A&A

View full text Add to dashboard Cite

Aims. We study the spectroscopic binary system Gl 375 to characterise its orbit and the spectral types and chromospheric activity levels of the components. Methods. We employed medium-resolution echelle spectra obtained at the 2.15 m telescope at the Argentinian observatory CASLEO and photometric observations obtained from the ASAS database. Results. We have separated the composite spectra into those corresponding to both components. The separated spectra allow us to confirm that the spectral types of both components are similar (dMe3.5) and to obtain precise measurements of the orbital period (P = 1.87844 days), minimum masses (M 1 sin 3 i = 0.35 M and M 2 sin 3 i = 0.33 M ), and other orbital parameters. The photometric observations exhibit a sinusoidal variation with the same period as the orbital period. We interpreted this as signs of active regions carried along with rotation in a tidally synchronised system, and studied the evolution of the amplitude of the modulation on longer timescales. Together with the mean magnitude, the modulation exhibits a roughly cyclic variation with a period of around 800 days. This periodicity is also found in the flux of the Ca II K lines of both components, which seem to be in phase.Conclusions. The periodic changes in the three observables are interpreted as a sign of a stellar activity cycle. Both components appear to be in phase, which implies that they are magnetically connected. The measured cycle of ≈2.2 years (≈800 days) is consistent with previous determinations of activity cycles in similar stars.

show abstract

“…We have recently become aware of the work by Montes et al (2006), who derive orbital parameters for this system in good agreement with the ones presented in this work.…”

Section: Discussionsupporting

confidence: 81%

The spectroscopic binary system Gl 375

Díaz¹,

González

Cincunegui³

et al. 2007

A&A

View full text Add to dashboard Cite

show abstract

“…Chromospheric activity produces a filling-in or emission in some strong photospheric lines. Typically, we use the strong lines as chromospheric activity indicators (Montes et al 2004;Zhang 2011). These indicators are summarized as follows:…”

Section: Chromospheric Activity Indicatorsmentioning

confidence: 99%

“…However, their emissions are above the continuum for many active stars. Furthermore, the ratio of EW Hα /EW Hβ can also be used as a diagnostic indicator for discriminating between plages and prominences (Hall & Ramsey 1992;Montes et al 2004), and as a diagnostic tool for the presence of non-thermal electrons (Kashapova et al 2008). According to the Buzasi model (Buzasi 1989), a low ratio (1-2) indicates the presence of a plage or prominence viewed against the stellar disk, but a high ratio (> 3, to a theoretical maximum of about 15) signals extended regions viewed off the limb of the star (Hall & Ramsey 1992).…”

Section: The Hα Hβ and Other Balmer Linesmentioning

confidence: 99%

Chromospheric activity in several single late-type stars

Zhang¹,

Pi²,

Zhu³

2015

Res. Astron. Astrophys.

View full text Add to dashboard Cite

New high-resolution echelle spectra of six single late-type Pleiades-like stars (V368 Cep, EP Eri, DX Leo, GJ 211, PW And and V383 Lac) were obtained with the 2.16 meter telescope at Xinglong Station in 2008-2010. Using the spectral subtraction technique, we analyzed our spectroscopic data and calculated the equivalent widths of excess emission from several indicators of chromospheric activity (Na I D 1 , D 2 , Hα and Ca II infrared triplet lines). All our results using chromospheric activity indicators confirmed the previous findings. In addition, the maximum amplitudes of chromospheric rotational modulation and the ratio of EW 8542 /EW 8498 were found to rise with increasing v sin i velocity.

show abstract

“…Thus, by analyzing the distortion of the spectral lines and their correlation with the RV, or by analyzing line ratios sensitive to the effective temperature, it is possible to verify the presence of stellar spots. In addition to the photospheric spots, cool stars, especially the rapidly rotating younger ones, have very active chromospheres (Montes et al 2004). The chromospheric spectrum is dominated by emission lines, which again can distort the photospheric absorption line profiles, or in extreme cases can even fill them up or turn them into emission lines.…”

Section: Analysis Of the Stellar Activitymentioning

confidence: 99%

“…In addition to the photospheric spots, cool stars, especially the rapidly rotating younger ones, have very active chromospheres (Montes et al 2004). The chromospheric spectrum is dominated by emission lines, which again can distort the photospheric absorption line profiles, or in extreme cases can even fill them up or turn them into emission lines.…”

Section: Analysis Of the Stellar Activitymentioning

confidence: 99%

Radial velocity variations in the young eruptive star EX Lupi

Kóspál

Mohler-Fischer

Sicilia‐Aguilar

et al. 2013

A&A

View full text Add to dashboard Cite

Context. EX Lup-type objects (EXors) are low-mass pre-main sequence objects characterized by optical and near-infrared outbursts attributed to highly enhanced accretion from the circumstellar disk onto the star. Aims. The trigger mechanism of EXor outbursts is still debated. One type of theory requires a close (sub)stellar companion that perturbs the inner part of the disk and triggers the onset of the enhanced accretion. Here, we study the radial velocity (RV) variations of EX Lup, the prototype of the EXor class, and test whether they can be related to a close companion. Methods. We conducted a five-year RV survey, collecting 54 observations with HARPS and FEROS. We analyzed the activity of EX Lup by checking the bisector, the equivalent width of the Ca 8662 Å line, the asymmetry of the Ca II K line, the activity indicator S FEROS , the asymmetry of the cross-correlation function, the line depth ratio of the VI/FeI lines, and the TiO, CaH 2, CaH 3, CaOH, and Hα indices. We complemented the RV measurements with a 14-day optical/infrared photometric monitoring to look for signatures of activity or varying accretion. Results. We found that the RV of EX Lup is periodic (P = 7.417 d), with stable period, semi-amplitude (2.2 km s −1 ), and phase over at least four years of observations. This period is not present in any of the above-mentioned activity indicators. However, the RVs of narrow metallic emission lines suggest the same period, but with an anti-correlating phase. The observed absorption line RVs can be fitted with a Keplerian solution around a 0.6 M central star with m sin i = (14.7 ± 0.7) M Jup and eccentricity of e = 0.24. Alternatively, we attempted to model the observations with a cold or hot stellar spot as well. We found that in our simple model, the spot parameters needed to reproduce the RV semi-amplitude are in contradiction with the photometric variability, making the spot scenario unlikely. Conclusions. We qualitatively discuss two possibilities to explain the RV data: a geometry with two accretion columns rotating with the star, and a single accretion flow synchronized with the orbital motion of the hypothetical companion; the second scenario is more consistent with the observed properties of EX Lup. In this scenario, the companion's mass would fall into the brown dwarf desert, which, together with the unusually small separation of 0.06 au would make EX Lup a unique binary system. The companion also has interesting implications on the physical mechanisms responsible for triggering the outburst.

show abstract

LU Vel (GJ 375): A M3.5Ve Flare and Double-Lined Spectroscopic Binary

Cited by 6 publications

References 2 publications

The spectroscopic binary system Gl 375

The spectroscopic binary system Gl 375

Chromospheric activity in several single late-type stars

Radial velocity variations in the young eruptive star EX Lupi

Contact Info

Product

Resources

About