A revised spectroscopic orbit for 93 Leonis (HD 102509)

Batten, Alan H.; Fisher, W. A.; Fletcher, J. M.; Hill, Graham

doi:10.1086/131251

Cited by 7 publications

(19 citation statements)

References 2 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Eggen (1985) included 93 Leo in a catalogue of ‘probable members of the Hyades supercluster’. There was a discrepancy of 9 km s −1 between the radial velocity required by membership and the γ‐velocity according to Cannon's (1910) orbit, but Eggen repeatedly referred to the ‘poor orbit’ and said that membership was not ruled out by it, notwithstanding the then‐new orbit, with a very similar γ‐velocity, by Batten et al (1983). It does not now seem likely that 93 Leo is in any way related to the Hyades.…”

Section: Introductionmentioning

confidence: 99%

“…Cowley (1976) gave the classification A7 V and G III. Batten et al (1983) quoted a classification by Abt, communicated to them privately, of A6 V: + F8 III; in a paper in collaboration with Morrell, Abt himself (Abt & Morrell 1995) gave the types as A6 III + F8 III. Basri, Laurent & Walter (1985) estimated a type as early as A3 V for the secondary from IUE spectra.…”

Section: Introductionmentioning

confidence: 99%

“…Young & Koniges (1977) referred to ‘moderately strong emission’ that was displaced by −50 km s −1 with respect to the absorption lines; however, their assertion that 93 Leo ‘is ostensibly a single‐line binary of spectral type F8, either on or slightly above the main sequence’ caused them to confuse the secondary's prominent K line with the line in the primary star, and they were therefore obliged to attribute the emission to an unseen main‐sequence secondary star. Batten et al (1983), commenting on Young & Koniges' report, considered that an appearance of emission can arise simply as a result of the wavelength separation of the K lines of the two component stars at phases near the nodes of the orbit. Fernandez‐Figueroa et al (1994) agreed with Batten et al in concluding that any emission is ‘not obvious’; on the other hand Strassmeier (1994), whose paper (like those of Batten et al and Fernandez‐Figueroa et al) includes actual spectrum tracings of the K line, found ‘strong emission’ after they subtracted from the observed spectrum the spectrum of the A5 V star θ 1 Ser, intended to serve as a proxy for the hot component of the system.…”

Section: Introductionmentioning

confidence: 99%

“…An important contribution to our knowledge of 93 Leo was provided by Hummel et al (1995), who were able routinely to resolve the system with their ‘Mark III’ optical interferometer and produce a ‘visual’ orbit for it. They adopted from the spectroscopic orbit (Batten et al 1983) the period and the zero eccentricity, and imposed on their solution certain other parameters that were not accurately determinable from their own observations. The really significant quantities yielded by the solution were the angular semi‐axis major of 0.0075 ± 0.0001 arcsec, and the orbital inclination of .…”

Section: Introductionmentioning

confidence: 99%

“…Huisong & Xuefu (1987) measured v sin i as 10 km s −1 , whereas Eaton (1990) found it to be 5 ± 2 km s −1 . The projected rotational velocity of the hot star has been given as 110 km s −1 by Markowitz (1969) and as 130 km s −1 by Batten et al (1983).…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Composite spectra Paper 13: 93 Leonis, a chromospherically-active binary

Griffin

2004

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

We isolate the spectrum of the secondary component of the composite‐binary system 93 Leonis by spectrum subtraction, classify it, and measure the mass ratio of the system. An accurate visual orbit and a well‐determined parallax provide reliable measurements of orbital inclination and distance, enabling us to determine precisely the individual masses and other stellar parameters. The primary star is of type ∼G7 III, and the secondary is a rapidly rotating star of type A7 IV. Our photographic spectra at 10 Å mm−1 are invaluable for accurate spectral classification in such cases. By combining 23 measurements of the secondary's velocity with 102 of the primary's and deriving a double‐lined orbit, we determine the mass ratio (q=M1/M2) of 93 Leo to be 1.09 ± 0.04. The same value is derived by cross‐correlating high‐dispersion spectra of 93 Leo B extracted from opposite nodal phases. That value of q is consonant with previous research, but its precision is considerably improved. We show that random errors arising from the cross‐correlation of broad, weak features constitute a natural limit to that precision. The derived masses of M1= 2.2 M⊙, M2= 2.0 M⊙ for the giant and dwarf, respectively, constrain the choice of models for fitting evolutionary tracks in the (log Teff, log L) plane. The giant is almost certainly on its first ascent of the red giant branch, and the dwarf has evolved significantly from the main sequence. The stars fit an isochrone for log(age) = 8.95, about 0.9 Gyr. Metallicity near to solar is suggested by the close correspondence between the component spectra and those of the respective solar‐abundance standards. The primary in 93 Leo displays a marked level of chromospheric activity. By combining our high‐dispersion spectra we are able to isolate emission in the Ca ii K line. The chromospheric material has a small infall velocity, giving rise to a disc‐averaged redshift of about 4 km s−1, and an unchanging velocity profile which can be attributed to a large number of small, active events like prominences across the surface. While we can say that there was no perceptible change in the emission strength over an interval of 4 months, we have not made systematic observations to monitor its long‐term stability. We contrast the components of 93 Leo with those of α Equ, whose analysis was the subject of Paper 11 in this series. The primary components are very similar, but the two secondary components are extremely different in nature: whereas 93 Leo B is a broad‐lined, apparently normal A star, the secondary of α Equ is a sharp‐lined Am star of type ∼kA3hA4mA9. We question why that should be, and recommend that a greater emphasis be placed on extracting accurate stellar parameters from the components of spectroscopic binaries as a means towards a better understanding of the vagaries of stellar evolution. 93 Leo has a 9‐mag visual companion which appears to be a physical member of the system and to be a single‐lined spectroscopic binary with a period of the order of a century.

show abstract

Section: Introductionmentioning

confidence: 99%