Main-sequence variable stars in young open cluster NGC 1893

Lata, Sneh; Yadav, R. K. S.; Pandey, A. K.; Richichi, A.; Eswaraiah, Chakali; Kumar, Brijesh; Kappelmann, N.; Sharma, Saurabh

doi:10.1093/mnras/stu726

Cited by 26 publications

(51 citation statements)

References 60 publications

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“…and variables with periods < 6 days have masses 2 M⊙, whereas out of 3 high mass variables (M > 3 M⊙), 2 have periods ∼1 days. A similar trend has been reported by Lata et al (2014Lata et al ( , 2016. Littlefair et al (2005) have also found a strong correlation between stellar mass and rotation rate in the case of IC 348.…”

Section: Correlation Of Periods/amplitudes Of Variables With Their Stsupporting

confidence: 86%

“…19 indicates that stars with periods up to ∼6 days are uniformly distributed for the entire range of ages of the PMS sources, whereas all the PMS variables having periods > 6 days are younger than 2 Myr. Lata et al (2014Lata et al ( , 2016 have also found a similar result that PMS stars with age 3 Myr seem to be relatively fast rotators. The right panel of Fig.…”

Section: Correlation Of Periods/amplitudes Of Variables With Their Stmentioning

confidence: 58%

“…has been extensively studied (e.g., Balona et al 1997;Balona & Dziembowski 2011;Handler & Meingast 2011;Mowlavi et al 2013). A new class of variable stars situated in the HR diagram between the red end of SPB and the blue end of δ Scuti, where stars are not expected to occur according to the classical stellar models, are also reported (see e.g., Mowlavi et al 2013;Lata et al 2014).…”

Section: Ms/field Variablesmentioning

confidence: 99%

“…The presence of circumstellar patchy dust clouds causes photometric variation c 2019 The Authors in most Herbig Ae/Be stars (van den Ancker et al 1998). Apart from PMS variables, many MS stars also show variability, e.g., β Cep type stars, slowly pulsating B-type stars (SPB) and δ Scuti stype stars, due to their pulsating behaviour (Mowlavi et al 2013;Lata et al 2014).…”

Section: Introductionmentioning

confidence: 99%

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Variable stars in the Sh 2-170 H ii region

Sinha

Sharma

Pandey

et al. 2020

Monthly Notices of the Royal Astronomical Society

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We present multi-epoch deep (∼20 mag) I c band photometric monitoring of the Sh 2-170 star-forming region to understand the variability properties of pre-main-sequence (PMS) stars. We report identification of 47 periodic and 24 non-periodic variable stars with periods and amplitudes ranging from ∼4 hrs to 18 days and from ∼0.1 to 2.0 mag, respectively. We have further classified 49 variables as PMS stars (17 Class ii and 32 Class iii) and 17 as main-sequence (MS)/field star variables. A larger fraction of MS/field variables (88%) show periodic variability as compared to the PMS variables (59%). The ages and masses of the PMS variable stars are found to be comparable with those of T-Tauri stars. Their variability amplitudes show an increasing trend with the near-IR/mid-IR excess. The period distribution of the PMS variables shows two peaks, one near ∼1.5 days and the other near ∼4.5 days. It is found that the younger stars with thicker discs and envelopes seem to rotate slower than their older counterparts. These properties of the PMS variables support the disc-locking mechanism. Both the period and amplitude of PMS stars show decrease with increasing mass probably due to the effective dispersal of circumstellar discs in massive stars. Our results favour the notion that cool spots on weak line T-Tauri stars are responsible for most of their variations, while hot spots on classical T-Tauri stars resulting from variable mass accretion from an inner disc contribute to their larger amplitudes and irregular behaviours.

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Section: Correlation Of Periods/amplitudes Of Variables With Their Stsupporting

confidence: 86%

Section: Correlation Of Periods/amplitudes Of Variables With Their Stmentioning

confidence: 58%

Section: Ms/field Variablesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Variable stars in the Sh 2-170 H ii region

Sinha

Sharma

Pandey

et al. 2020

Monthly Notices of the Royal Astronomical Society

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“…Two Maia candidates were also observed. These results, together with the anomalous cluster stars observed by Mowlavi et al (2013) and Lata et al (2014) and several well-observed brighter stars, leave little doubt that these two kinds of anomalous pulsating stars do exist.…”

Section: Discussionmentioning

confidence: 60%

The hot γ Doradus and Maia stars

Balona

Engelbrecht

Joshi

et al. 2016

Mon. Not. R. Astron. Soc.

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The hot γ Doradus stars have multiple low frequencies characteristic of γ Dor or SPB variables, but are located between the red edge of the SPB and the blue edge of the γ Dor instability strips where all low-frequency modes are stable in current models of these stars. Though δ Sct stars also have low frequencies, there is no sign of high frequencies in hot γ Dor stars. We obtained spectra to refine the locations of some of these stars in the H-R diagram and conclude that these are, indeed, anomalous pulsating stars. The Maia variables have multiple high frequencies characteristic of β Cep and δ Sct stars, but lie between the red edge of the β Cep and the blue edge of the δ Sct instability strips. We compile a list of all Maia candidates and obtain spectra of two of these stars. Again, it seems likely that these are anomalous pulsating stars which are currently not understood.

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