Long-term monitoring of active 
stars

Cutispoto, G.

doi:10.1051/aas:1998430

Cited by 40 publications

(80 citation statements)

References 56 publications

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“…The membership of HD155555AB to the β Pictoris moving group was first suggested by Zuckerman et al [2001] based on distance, UVW velocity components, high v sin i, and L X / L bol ratio. Also the photometric variability observed by Eggen (1978) and Cutispoto (1998) are in agreement with the youth of the system. The present investigation is focused on the fainter HD 155555C component (also named LDS 587B) which is a M3.5 dwarf (Pasquini et al 1991).…”

Section: Literature Informationsupporting

confidence: 81%

“…Then, the difference of rotation periods can be explained considering the different nature of the components. The SB2 components that rotate with P = 1.687d have already reached a tidal synchronization, their orbital and rotation period being equal (Strassmeier et al 2000;Cutispoto 1998). The single dM is still contracting and spinning up its rotation rate while approaching the zero-age main-sequence.…”

Section: Resultsmentioning

confidence: 99%

“…The spectroscopic binary HD 155555AB was discovered by Bennet et al [1967] to be composed of G5IV + K0IV stars that rotate with an orbital period P = 1.687 d. First evidence of photometric variability of this SB2 was found by Eggen [1978] after comparing his photometry collected in 1978 (V = 6.83, B−V = 0.835, U−B = 0.29, R = 6.46, and R−I = 0.325 mag) with the earlier photometry collected by Stoy [1963] (V = 6.67 and B−V = 0.80 mag), even though the latter also included the dM companion, owing to the large aperture of 44 used to collect the photoelectric photometry. Subsequent long-term photometric monitoring by Cutispoto (see, e.g., Cutispoto 1998 and references therein) revealed robust evidence of the existence of short-and long-term photometric variability. HD 155555AB has the variable's name V824 Ara in the Combined General Catalogue of Variable Stars [Kholopov 1998].…”

Section: Literature Informationmentioning

confidence: 97%

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Photometric study of HD 155555C in the β Pictoris Association

Messina

Millward²,

Bradstreet

2015

New Astronomy

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We are carrying out a series of photometric monitoring to measure the rotation periods of members in the young β Pictoris Association, as part of the RACE-OC project (Rotation and ACtivity Evolution in Open Clusters). In this paper, we present the results for HD 155555C which is believed to be physically associated to the spectroscopic binary V824 Ara (HD155555) and thus constituting a triple system. We collected B, V, and R-band photometric data timeseries and discovered from periodogram analysis the rotation period P = 4.43 d. Combined with stellar radius and projected rotational velocity, we find this star almost equator-on with an inclination i 90 • . The rotational properties of HD155555C fit well into the period distribution of other β Pic members, giving further support to the suggested membership to the association and to its physical association to V824 Ara. A comparison with Pre-Main-Sequence isochrones from various models allows us to estimate an age of 20±15 Myr for this triple system.

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Section: Literature Informationsupporting

confidence: 81%

Section: Resultsmentioning

confidence: 99%

Section: Literature Informationmentioning

confidence: 97%

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Photometric study of HD 155555C in the β Pictoris Association

Messina

Millward²,

Bradstreet

2015

New Astronomy

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“…Neither of these algorithms shows a solution with a high power and the most likely periods differ when deleting 20% of data randomly. This suggests that apart from the brightness variation of HD 102077 due to stellar activity as has also been seen in the shorter period observations (Cutispoto 1990(Cutispoto , 1993(Cutispoto , 1998 no other signal can be detected in the H data.…”

Section: V-band Variabilitysupporting

confidence: 54%

“…Fabricius & Makarov (2000) analysed the H Tycho data and find that the brighter component has a redder B − V colour, corresponding to spectral types K4 and K2, but they do not give an explanation for this unexpected result. Cutispoto (1998) uses the U BVRI colours of the integrated system and ∆H p from the H satellite catalog to classify HD 102077 as consisting of a K0/1V and a K5V.…”

Section: Introductionmentioning

confidence: 99%

The young binary HD 102077: Orbit, spectral type, kinematics, and moving group membership

Wöllert

Brandner

Reffert³

et al. 2014

A&A

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The K-type binary star HD 102077 was proposed as a candidate member of the TW Hydrae association (TWA) which is a young (5−15 Myr) moving group in close proximity (∼50 pc) to the solar system. The aim of this work is to verify this hypothesis by different means. We first combine diffraction-limited observations from the ESO NTT 3.5 m telescope in SDSS-i and SDSS-z passbands (three epochs) and ESO 3.6 m telescope in H-band (one epoch) with literature data to obtain a new, amended orbit fit of the visual binary. We then estimate the spectral types of both components from the i − z colours and reanalyse the H parallax and proper motion taking the orbital motion into account. Moreover, we use two high-resolution spectra of HD 102077 obtained with the fibre-fed optical echelle spectrograph FEROS at the MPG/ESO 2.2 m telescope to determine the radial velocity and the lithium equivalent width (EW) of the system. Finally, we use all the information to discuss the kinematic properties of HD 102077 and to estimate the age of the system. The orbital elements of the HD 102077 trajectory are well constrained and we derive a total system mass of 2.6 ± 0.8 M and a semi-major axis of 14.9 ± 1.6 AU. From the i − z colours we infer an integrated spectral type of K2V, and individual spectral types of K0 ± 1 and K5 ± 1 for primary and secondary, respectively. The radial velocity corrected for the orbital motion of the system is 17.6 ± 2 km s −1 . Even though the parallax determination from the H data is not influenced by the orbital motion, the proper motion changes to µ α * cos δ = −137.84 ± 1.26 mas yr −1 and µ δ = −33.53 ± 1.45 mas yr −1 . With the resultant space motion, the probability of HD 102077 being a member of TWA is less than 1%. Furthermore, the lithium equivalent width of 200 ± 4 mÅ is consistent with an age between 30 Myr and 120 Myr and thus older than the predicted age of TWA. The comparison of HD 102077's temperature and luminosity to isochrones supports this result. In conclusion, HD 102077's age, galactic space motion, and position do not fit TWA or any other young moving group.

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Flare stars in the TW Hydrae association: the HIP 57269 system

et al. 2003

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Abstract. We discuss a new member candidate of the TW Hydrae association (TWA) among the stars of the Gershberg et al. (1999) flare star catalog. TWA is one of the closest known associations of young stars at about 60 pc. Three supposedly young flare stars are located in the same region of the sky as TWA. One of them (HIP 57269) shows strong Lithium absorption with spectral type K1/K2V and a high level of chromospheric and coronal activity. It is located at a distance of 48.7 ± 6.3 pc in common with the five TWA members observed with Hipparcos (46.7 to 103.9 pc). HIP 57268 A has a wide companion C which also shows Lithium absorption at 6707Å and which has common proper motion with HIP 57269, as well as a close companion resolved visually by Tycho. HIP 57269 A&C lie above the main sequence and are clearly pre-main-sequence stars. The UVW-space velocity is more consistent with the star system being a Pleiades super cluster member. The two other flare stars in the TWA sky region do not show Lithium at all and are, hence, unrelated.

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Long-term monitoring of active stars

Cited by 40 publications

References 56 publications

Photometric study of HD 155555C in the β Pictoris Association

Photometric study of HD 155555C in the β Pictoris Association

The young binary HD 102077: Orbit, spectral type, kinematics, and moving group membership

Flare stars in the TW Hydrae association: the HIP 57269 system

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