• R. F. Griffin

Articles written in Journal of Astrophysics and Astronomy

• A spectroscopic orbit for 26 Comae

Photoelectric radial-velocity measurements show that 26 Comae is a spectroscopic binary with a very eccentric orbit and a period of 972 days.

• A spectroscopic orbit for 26 Comae

• A spectroscopic orbit for HD 115968

Photoelectric radial-velocity measurements show that the eighth-magnitude star HD 115968 is a spectroscopic binary with a period of 16.195 days. The star has a large proper motion, and is unlikely to have the luminosity corresponding to the spectral type of G8 III favoured by Zaitseva. It is most probably a late-G dwarf.

• Spectroscopic binaries near the north galactic pole - Paper 3: HD 105341

Photoelectric radial-velocity measurements show that HD 105341 is a spectroscopic binary with a near-circular orbit and a period of 194 days.

• Spectroscopic binaries near the north Galactic pole - Paper 4: HD120803

Photoelectric radial-velocity measurements show that HD 120803 is a spectroscopic binary with a rather eccentric orbit and a period of 700 days. Early DDO photographic observations, published individually here for the first time, fit the orbit well.

• Spectroscopic binaries near the north Galactic pole - Paper 5: HD 117064

Photoelectric radial-velocity measurements, which, in 1971 showed HD 117064 to be a spectroscopic binary, have been continued and now permit the derivation of an eccentric orbit with a period of 6.08 years.

• Spectroscopic binaries near the North Galactic Pole paper 6: BD 33° 2206

Photoelectric radial-velocity measurements have confirmed O. C. Wilson’s finding that BD 33° 2206, the secondary star in the wide visual binary ADS 8470, is a spectroscopic binary. It has an eccentric orbit with a period of 100 days. Its γ-velocity is close to the constant radial velocity of the visual primary, confirming the physical association of the stars.

• Spectroscopic binaries near the north Galactic pole paper 7: HD 107742

Photoelectric radial-velocity measurements show that HD 107742 is a spectroscopic binary with a period of 875 days and a small (but definitely non-zero) eccentricity. The star is not a member of the Coma Cluster, against which it is seen projected.

• Spectroscopic binaries near the north Galactic pole paper 8: HD 121844

Photoelectric radial-velocity measurements show that HD 121844 is a spectroscopic binary with a period of 303 days, a high eccentricity (0.49) and a high negative γ-velocity (- 61 km s-1).

• Spectroscopic binaries near the north galactic pole paper 9: HD 116378

Photoelectric radial-velocity measurements show that HD 116378 is a spectroscopic binary with a period of 17.76 days. The visual companion star is not physically related to it.

• Spectroscopic binaries near the north galactic pole - Paper 10: HR 4668

Photoelectric radial-velocity measurements confirm and refine the preliminary orbit derived for HR 4668 by Christie on the basis of eight Lick spectrograms taken more than 50 years ago.

• Spectroscopic binaries near the north galactic pole - Paper 11: HD 105982

Photoelectric radial-velocity measurements show that HD 105982 is a spectroscopic binary with a period of 3.7 years.

• Spectroscopic binaries near the North Galactic pole - Paper 12:6 Boötis

Photoelectric radial-velocity measurements show that 6 Boötis undergoes small periodic variations of velocity. An orbit with a 2.6-year period and a semi-amplitude of little more than 1 km s-1 is derived. The amplitude is smaller by a factor of two than that of any plausible orbit previously derived from radial velocities.

• Spectroscopic binaries near the north galactic pole - Paper 13: HD 110195

Photoelectric radial-velocity measurements show that the tenth-magnitude object HD 110195 is a double-lined spectroscopic binary. It consists of two very similar late-G dwarfs in an orbit having high eccentricity and a period of 18 days.

• Spectroscopic binaries near the North Galactic Pole paper 14: HD 118234

Photoelectric radial-velocity measurements show that the Seventh-magnitude star HD 118234 is a spectroscopic binary in a very eccentric 59-day orbit.

• Spectroscopic binaries near the North Galactic Pole paper 15: HD 106947

Photoelectric radial-velocity measurements show that HD 106947 is a double-lined spectroscopic binary. The components have spectral types of about F6 V and G5 V and are in a 59-day orbit of moderate eccentricity. The system is a member of the Coma Cluster.

• Spectroscopic binaries near the North Galactic Pole paper 16: HD 116093

Photoelectric radial-velocity measurements show that HD 116093 is a double-lined spectroscopic binary in a very eccentric 53-day orbit. Very little else is known about the system, but circumstantial evidence is consistent with the hypothesis that the components’ types are near to F3 V and F8 V. If that is so, the orbit must be seen very nearly edge-on; a search for eclipses is warranted and an ephemeris for them is given.

• HD 115781 and HD 116204—two RS CVn binaries

HD 115781 and HD 116204 (BL CVn and BM CVn) are shown to be RS CVn binaries with periods near 20 days. HD 115781 is double-lined; the primary type is about K1III, while the secondary is probably a late-type subgiant. The masses of the two components are equal within observational error. There is substantial photometric variability with a period half the orbital period; it is attributed to ellipsoidal variation. HD 116204 is also of type K1III. It shows exceptionally strong Ca II H and K emission, together with an emission-line spectrum typical of RS CVn stars in theIUE ultraviolet region, but Hα is an absorption line. The secondary star in the HD 116204 system has not been detected. The primary shows photometric variations, presumably due to starspots, with a period 5 per cent longer than the orbital period.

• Spectroscopic binaries near the North Galactic Pole paper 17: HD 111425

Photoelectric radial-velocity measurements show that HD 111425 is a double-lined spectroscopic binary, whose components probably have types of about F8 V and G6 V and are in a 51-day orbit of moderate eccentricity

• The chromospherically active solar-type spectroscopic binary HD 191262

HD 191262 is a double-lined spectroscopic binary consisting of two slightly unequal solar-type stars in an orbit’ with a period of 5.43435 days. The system is both synchronized and circularized and is probably at least as old as the Sun. The inclination of the system is about 45°

• The spectroscopic orbit of 6 Draconis

6 Dra has long been known to show small variations in radial velocity, and there is photometric and spectroscopic evidence that its spectrum is composite. We show, largely on the basis of a generous number of photoelectric radial velocities mainly obtained at Cambridge and Fick observatories, that the orbit is of mild eccentricity and has a period of 562 days and a semi-amplitude of 7 km s−1.IUE observations show that the spectrum between 1600 and 1800 ∢ is consistent with its arising from a late-A main-sequence companion

• Composite spectra - Paper 5: Orbital elements for 30 systems

A comprehensive survey of bright composite-spectrum binaries in the northern sky has provided so many radial-velocity data that orbits can now be determined for many objects whose orbits were hitherto unknown or else insecure or actually erroneous. Elements are given for the orbits of 30 such objects, thereby more than doubling the number of composite-spectrum binaries with known orbits

• Spectroscopic binaries near the North Galactic Pole paper 18: HD 118670

Photoelectric radial-velocity measurements show that HD 118670 is a double-lined spectroscopic binary in an orbit which is not quite circular and whose period is about 48 days. Spectral types of K0 V and K7 V would satisfy the photometry and the mass ratio; the mass function would then suggest the possibility of eclipses. However, actual spectral classification indicates a luminosity somewhat above the main sequence

• Spectroscopic binaries near the North Galactic Pole paper 19: HR 4693

HR 4693 is a fifth-magnitude K2 III star whose radial-velocity nature has been the subject of conflicting ideas. It is shown here to be a spectroscopic binary of small amplitude, less than 2 km s-1; the orbit is quite eccentric and has a period of 16 years

• Spectroscopic binaries near the north galactic pole - Paper 20: HD 111068

Photoelectric radial-velocity measurements show that HD 111068 is a spectroscopic binary with a period of 206 days. The primary star is probably about type K5 III; the secondary, only detected through the photometric compositeness of the system, may well be an F dwarf. The orbit is circular within observational uncertainty; it is near the upper limit of periods for which tidal circularization operates for giant stars.

• Spectroscopic binaries near the north Galactic Pole - Paper 21: eight short-period binaries

Orbits based principally on radial-velocity measurements made with the Haute-Provence Coravel spectrometer are presented for eight binary systems which include some of the faintest HD stars in the Galactic-Pole field. They are HD 103418 (which is double-lined), 105021, 108151, 113169, 113323, 113650, 113714, and 116514. Their periods range from 3.7 to 15.1 days. Very little else is known about any of them.

• Spectroscopic binaries near the North Galactic Pole - Paper 22: HR 4793

Photoelectric radial-velocity observations, begun independently at Cambridge and at Ames by the respective authors and now including results from no fewer than six radial-velocity spectrometers, show that the K1 III star HR 4793 is a spectroscopic binary; it has a circular orbit with a period of 111 days and the quite modest amplitude of 7kms-1

• Spectroscopy and orbit determination of the chromospherically active double-lined binary system HD 163621 = V835 Herculis

HD 163621 is a double-lined spectroscopic binary in a circular orbit whose period is 3.3 days. Spectral classification of the components has proved difficult, but current results of K0 V and late K V are reasonably consistent with our best model of the system, which has spectral types of G8V and K7V. The object shows photometric variability and chromospheric activity and is therefore a member of the BY Draconis class of variables. The minimum masses are quite small, 0.10 and 0.07 M⊙ for the primary and secondary, respectively, suggesting an orbital inclination of about 30°. The system is synchronously rotating. Its distance is estimated to be 31 pc, which makes it an excellent candidate for a trigonometric parallax determination.

• Radial velocities andDDO, BV photometry of Henry Draper G5-M stars near the North Galactic Pole

Radial velocities are given for some 900 stars within 15‡ of the North Galactic Pole, including almost all such stars classified G5 or later in theHenry Draper Catalogue. Luminosities, two-dimensional spectral classes, composition indices, and distances are derived for the majority of the sample throughDDO andBV photometry. More than half of the stars are classified as G5-K5 giants: they show a clear relationship between composition and velocity dispersion for the two Galactic componentsV andW, and a less well-defined trend forU. Four abundance groups exhibit characteristics which imply association with, respectively, the thick disk, old thin disk, young thin disk, and Roman’s “4150” group. The sample is contained within l kpc of the Galactic plane, and no trends with distance are evident.

• Spectroscopic binaries near the North Galactic Pole paper 23: HD 111154

HD 111154 is a member of the Coma Cluster. It is here shown to be a somewhat unequal pair of stars of approximately solar type. They are in an orbit that has a period of just under 27 days and quite a high eccentricity (0.442). Although the minimum masses (1.08 and 1.00M) are large enough to encourage a search for eclipses, no such events have been detected.

• Spectroscopic binaries near the north Galactic pole paper 24: HD 106104, 109281, 109463 and 110743

The four stars treated in this paper have been under observation with photoelectric radial-velocity spectrometers for many years. They have proved to be binaries with periods of 30, 1828, 1514 and 822 days respectively; the orbits are of modest eccentricity apart from that of HD 110743 which is indistinguishable from a circle. The mass functions are small, and no companion has been observed for any of the stars. HD 110743, a K dwarf, is much the nearest of the four, and its orbit is of short enough period for the photocentric motion to have been recognized byHipparcos. An eleventh-magnitude star rather more than 1≈ away from HD 106104 is shown to be a genuine physical companion, with practically identical radial velocity, proper motion and distance modulus, although the projected separation is about 13,000 AU.

• Spectroscopic Binaries near the North Galactic Pole Paper 12A: 6 Boötis

About 25 years ago, in Paper 12 of this series, the author presented a spectroscopic orbit for 6 Boo. The velocity amplitude of little more than 1 km s-1 was much smaller than for any star whose orbit had been determined up till that time. Although it was objectively demonstrated that the orbit was very secure, a few years ago subjective misgivings prompted the author to restore the star to his observing programme. Newobservations of much higher precision confirm not only the spectroscopic-binary nature of 6 Boo but also, with almost astonishing fidelity, the elements already given for it.

• Photoelectric Radial Velocities, Paper XVIII Spectroscopic Orbits for Another 52 Binaries in the Hyades Field

Spectroscopic orbits are presented for 52 stars in the Hyades field, of which 41 prove to be actual members of the Hyades (with some reservations in two cases). Most of the stars concerned have not had orbits published for them previously. Three of them are of higher multiplicity. The already-known double-lined eclipsing system van Bueren 22 is demonstrated to be a triple system, as was obliquely announced 25 years ago; its outer’ orbit, which has a period of about 8 years, is now determined. Van Bueren 75 is already known to be triple, but here the visual secondary is shown to be the (single-lined) spectroscopic sub-system, and an independent spectroscopic solution is given for the 40-year orbit of what has hitherto been regarded as the visual’ pair. Van Bueren 102, for which a close visual companion was discovered comparatively recently, is a single-lined binary whose 𝛾-velocity has shown a steady drift over at least the last 30 (probably 50) years. Three stars, vB 39, 50 and 59, have notably high eccentricities of 0.85, 0.98 and 0.94, respectively; they have quite long periods (especially vB 50, which is over 100 years), and every one of them contrived to pass the whole of its recent periastron passage (about 180° of true anomaly) between seasons, at the time of year when the Hyades are unobservable!

• Photoelectric Radial Velocities, Paper XIX Additional Spectroscopic Binaries among the Redman K Stars

The `Redman K stars’ project, described more particularly in the paper immediately following this one, involved the repeated measurement on a quasi-annual basis of the radial velocities of a group of 86 seventh-magnitude late-type stars over an interval of 45 years. Certain of the stars proved to vary in velocity and were then transferred to a different observing programme, in which they were measured more frequently with a view to determining their orbits. Orbits have already been published for 18 of the stars. Presented here (and summarized in Table 9) are the results on six more; all are single-lined. One of them (HD 191046, a star which has a literature coverage about ten times as rich as that of any of the others, probably on account of its high space velocity which includes a 𝛾-velocity of nearly -100 km s-1) has a good orbit with a period of about 8000 days (22 years). Five others (HD 3345, 15728, 20509, 188058 and 191084) have orbits that are perfectly secure in principle, but their periods range between 40 and perhaps 70 years, and (particularly in some cases) their radial velocities have not been observed well enough for long enough to establish either the periods or the orbits very accurately. One star, HD 9354, has exhibited a monotonic variation of velocity throughout the duration of the observing programme; it is possible to draw a Keplerian velocity curve that does justice to the measurements, but it cannot be expected to have much predictive power.

• Photoelectric Radial Velocities, Paper XX 45 Years’ Monitoring of the Radial Velocities of the Redman K Stars

The ‘Redman K stars’ are a group of 80-odd seventh-magnitude late-type stars, nearly all giants, distributed along the Galactic equator between approximate longitudes 50° and 150° (roughly Sagitta to Cassiopeia). Their radial velocities have been measured systematically once per season in 30 of the 45 seasons from 1966 to 2010/11. At least 26 of them (30%) have proved to vary in velocity. Orbits have been derived for all but one of the 26, many of them having longer periods than have normally been associated with spectroscopic binaries; several are comparable with, or longer than, the present duration of the observing campaign. Also reported here are radial-velocity measurements made casually of stars seen in the fields of some of the Redman stars. Two of the companions have proved to vary in velocity on long time-scales, and (somewhat preliminary) orbits are given for them.

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