Population i pulsating stars

Tsvetkov, Ts.

doi:10.1007/bf00643629

Cited by 7 publications

(3 citation statements)

References 65 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The limit obtained from the L2.5 member (T191) is 50 Myr more stringent than from the L2.0 members. Age estimates for Coma Ber have ranged from 300 Myr to 1000 Myr (Tsvetkov 1989). For example, Kraus & Hillenbrand (2007) used an age of 400 Myr in their study of the low-mass population.…”

Section: Lithium Depletion and The Age Of Coma Bermentioning

confidence: 99%

See 1 more Smart Citation

Search for the sub-stellar lithium depletion boundary in the open star cluster Coma Berenices

Martín

Lodieu

2020

A&A

View full text Add to dashboard Cite

Aims. We mainly aim to search for the lithium depletion boundary (LDB) among the sub-stellar population of the open star cluster Coma Berenices. Methods. Since the number of brown dwarf candidates in Coma Ber available in the literature is scarce, we carried out a search for additional candidates photometrically using colour–magnitude diagrams combining optical and infrared photometry from the latest public releases of the following large-scale surveys: the United Kingdom InfraRed Telescope Infrared Deep Sky Survey (UKIRT/UKIDSS), the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS), the Sloan Digital Sky Survey (SDSS), and AllWISE. We checked astrometric consistency with cluster membership using Gaia DR2. A search for Li in three new and five previously known brown dwarf candidate cluster members was performed via spectroscopic observations using the OSIRIS instrument at the 10.4 m Gran Telescopio de Canarias (GTC). Results. A couple dozen new photometric candidate brown dwarfs located inside the tidal radius of Coma Ber are reported, but none of these are significantly fainter and cooler than previously known members. No LiI resonance doublet at 6707.8 Å was detected in any of eight Coma Ber targets in the magnitude range J = 15–19 and G = 20–23 observed with the GTC. Spectral types and radial velocities were derived from the GTC spectra. These values confirm the cluster membership of four L2–L2.5 dwarfs, two of which are new in the literature. Conclusions. The large Li depletion factors found among the four bona fide sub-stellar members in Coma Ber implies that the LDB must be located at spectral type later than L2.5 in this cluster. Using the latest evolutionary models for brown dwarfs, a lower limit of 550 Myr on the cluster age is set. This constraint has been combined with other dating methods to obtain an updated age estimate of 780 ± 230 Myr for the Coma Ber open cluster. Identification of significantly cooler sub-stellar cluster members in Coma Ber awaits the advent of the Euclid wide survey, which should reach a depth of about J = 23; this superb sensitivity will make it possible to determine the precise location of the sub-stellar LDB in this cluster and to carry out a complete census of its sub-stellar population.

show abstract

Section: Lithium Depletion and The Age Of Coma Bermentioning

confidence: 99%

“…Coma Ber has solar metallicity and negligible reddening in the line of sight (Taylor Article number, page 1 of 10 arXiv:2006.07280v1 [astro-ph.SR] 12 Jun 2020 2006). The age has not been well determined, a wide range of ages are found in the literature (300-1000 Myr;Tsvetkov 1989).…”

Section: Introductionmentioning

confidence: 99%

Search for the sub-stellar lithium depletion boundary in the open star cluster Coma Berenices

Martín

Lodieu

2020

A&A

View full text Add to dashboard Cite

show abstract

“…Amongst the work on δ Scuti stars in Praesepe, see Breger et al (1993), Alvarez et al (1998), Arentoft et al (1998) and Peña et al (1998). Praesepe is about old (Tsvetkov 1989) and has a distance modulus , i.e. a distance of (Mermilliod et al 1997 from Hipparcos parallaxes).…”

Section: Introductionmentioning

confidence: 99%

Photometric properties of the Scuti star BR Cancri

Zhou

Rodríguez‐López

Rolland

et al. 2001

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

We present the results of a three-year Johnson V and Stro Èmgren uvbyHb photometric study of the d Scuti star BR Cancri (BR Cnc). Our data sets consist of 1293 discrete differential magnitudes in Johnson V and yellow y filters, 883 in Stro Èmgren v and 239 in ub filters. The Fourier analysis of the data suggests four pulsation frequencies for the variable: f 1 24:978; f 2 11:358; f 3 11:808 and f 4 27:914 cycle d 21 : During the three observing years, the main frequency f 1 kept its V(y) amplitude constant at about 6 mmag but its v amplitude seems to be changing. Amplitude variations for all the three other frequencies are also claimed. The pulsation modes of the frequencies are discussed based on the colour data. Using uvbyb data and calibrations in the literature, we derive the physical parameters for BR Cnc.

show abstract