Chromospherically Active Stars. XXI. The Giant, Single-lined Binaries HD 89546 and HD 113816

Fekel, Francis C.; Henry, Gregory W.; Eaton, J. A.; Sperauskas, J.; Hall, D. S.

doi:10.1086/341612

Cited by 22 publications

(52 citation statements)

References 38 publications

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“…UX Ari also displays long-term variations in its mean brightness, suggesting cyclic behaviour. The RSM can reproduce such behaviour via the random appearance and decay of individual starspots without the need for a driving mechanism, as shown by the sample light curves generated by the RSM in Eaton et al (1996) and Fekel et al (2002).…”

Section: Spot Evolutionmentioning

confidence: 99%

BVphotometry of UX Ari in the period 1987–2002

Ulvås

Henry

2003

A&A

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Abstract. We present 14.3 years of previously unpublished photometric observations of UX Ari. The observations were obtained between 1987.9 and 2002.2 using the T3 0.4-metre Automatic Photoelectric Telescope at Fairborn Observatory and consist of 1228 B band and 1213 V band measurements. The comparison star was 62 Ari. We have analyzed the new data together with previously published photometric observations. The V magnitude shows variations with dominant periods of about 12 and 25 years, where the longest period seems to correspond to an activity cycle. The previously reported anticorrelation between the B − V colour and V magnitude variations is confirmed.

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Section: Spot Evolutionmentioning

confidence: 99%

BVphotometry of UX Ari in the period 1987–2002

Ulvås

Henry

2003

A&A

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“…Therefore, our measured rotation periods from the individual seasons probably have true errors larger than the formal uncertainties in the period analysis. As discussed by Fekel et al (2002), the observed photometric periods in chromospherically active stars must be interpreted with care, since they can be affected by the growth and decay of individual spots at various longitudes, as well as the formation of new and decay of old clumps of spots by differential rotation, so that the photometric period at any epoch may not correspond precisely to the rotation period of any stellar latitude. It appears, therefore, that our photometry does not successfully reveal any differential rotation in HD 37824.…”

Section: Photometric Analysismentioning

confidence: 99%

Chromospherically Active Stars. XXIV. The Giant, Single-lined Binaries HD 37824, HD 181809, and HD 217188

Fekel

Henry

2005

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We have obtained spectroscopy and photometry of three chromospherically active, single-lined spectroscopic binaries, HD 37824 (V1149 Ori), HD 181809 (V4138 Sgr), and HD 217188 (AZ Psc). HD 37824 has a circular orbit with a period of 53.57 days. Its primary is a K0 III star, while the secondary is likely a G or K dwarf. HD 181809 has an orbit with a period of 13.04667 days and a low eccentricity of 0.040. The primary has a spectral type of K0 III-IV, and its secondary is probably an M dwarf. The orbit of HD 217188 has a period of 47.1209 days and a moderately high eccentricity of 0.470. The spectral type of the primary is K0 III, while the secondary is likely an M dwarf. All three systems are estimated to have near solar iron abundances. Photometric observations spanning 15-16 years for all three stars yield mean photometric periods of 53.12, 59.85, and 90.89 days for HD 37824, HD 181809, and HD 217188, respectively. Thus, HD 37824 is rotating synchronously with the orbital period, while HD 181809 and HD 217188 are both rotating considerably slower than synchronously. All three stars show longterm variations in mean brightness and photometric amplitude, but no correlations are observed between the seasonal mean brightness, photometric amplitude, and seasonal photometric period in any of the stars. No clear evidence for long-term periodic variations in any of these parameters is present. The circular orbit of HD 37824 and the synchronous rotation of its K giant argue that the star is in the core helium-burning phase of its evolution. The giant components of HD 181809 and HD 217188 are asynchronous rotators, and both systems have eccentric orbits. Thus, those two stars are likely first-ascent giants.

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“…V2253 Oph is a short-period asynchronously-rotating star in a binary with an orbital period 15 times longer than the stellar rotation period. Its orbit is only slightly eccentric, if at all, because zero eccentricity is within 3σ of the value given by Fekel et al (2002). Thus, the period difference could not be due to pseudosynchronization.…”

Section: Introductionmentioning

confidence: 86%

“…Its inclination of the rotational axis is coplanar to the orbit, which itself is highly eccentric (Griffin 1988). The third system, IS Vir, is a synchronized giant in a marginally eccentric orbit (Fekel et al 2002).…”

Section: Introductionmentioning

confidence: 99%

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Long‐term photometry of three active red giants in close binary systems: V2253 Oph, IT Com and IS Vir

Oláh¹,

Moór²,

Strassmeier³

et al. 2013

Astron Nachr

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We present and analyze long-term optical photometric measurements of the three active stars V2253 Oph, IT Com and IS Vir. All three systems are single-lined spectroscopic binaries with an early K giant as primary component but in different stages of orbital-rotational synchronization. Our photometry is supplemented by 2MASS and WISE near-IR and mid-IR magnitudes and then used to obtain more accurate effective temperatures and extinctions. For V2253 Oph and IT Com, we found their spectral energy distributions consistent with pure photospheric emission. For IS Vir, we detect a marginal mid-IR excess which hints towards a dust disk. The orbital and rotational planes of IT Com appear to be coplanar, contrary to previous findings in the literature. We apply a multiple frequency analysis technique to determine photometric periods, and possibly changes of periods, ranging from days to decades. New rotational periods of 21.55±0.03 d, 65.1±0.3 d, and 23.50±0.04 d were determined for V2253 Oph, IT Com, and IS Vir, respectively. Splitting of these periods led to tentative detections of differential surface rotations of δP/P ≈ 0.02 for V2253 Oph and 0.07 for IT Com. Using a time-frequency technique based on short-term Fourier transforms we present evidence of cyclic light variations of length ≈ 10 yr for V2253 Oph and 5-6 yr for IS Vir. A single flip-flop event has been observed for IT Com of duration 2-3 yr. Its exchange of the dominant active longitude had happened close to a time of periastron passage, suggesting some response of the magnetic activity from the orbital dynamics. The 21.55-d rotational modulation of V2253 Oph showed phase coherence also with the orbital period, which is 15 times longer than the rotational period, thus also indicating a tidal feedback with the stellar magnetic activity.

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Chromospherically Active Stars. XXI. The Giant, Single-lined Binaries HD 89546 and HD 113816

Cited by 22 publications

References 38 publications

BVphotometry of UX Ari in the period 1987–2002

BVphotometry of UX Ari in the period 1987–2002

Chromospherically Active Stars. XXIV. The Giant, Single-lined Binaries HD 37824, HD 181809, and HD 217188

Long‐term photometry of three active red giants in close binary systems: V2253 Oph, IT Com and IS Vir

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