NOTES from OBSERVATORIES 171 in Conclusion It Is a Pleasure To

NOTES FROM OBSERVATORIES 171

In conclusion it is a pleasure to thank Dr. D. M. Popper for pointing out the importance of this star, for information regarding the spectrum, and for valuable suggestions regarding this note.

BEFEBENCES

Neubauer, F. J. 1930, Pub. A.S.P.42, 235. Oke, J. B. 1964, Ap. J.140, 689.

UBV PHOTOMETRY OF THE LOWELL PROPER MOTION OBJECT 0175-34

B. H. HABDIE AND A. M. HEISEB Dyer Observatory, Vanderbilt University

Received December 6, 1963

In a recent publication Giclas, Bumham, and Thomas (1965) have reported that the object G175—34, whose proper motion is 2^37/ year, is also a visual binary with a 6^8 separation, designated as Stein 2051 in the Lick Observatory Index Catalogue of Visual Double Stars. They also note "the western component is stronger on the red plate" of the Palomar 48-inch plates of this area and that one of the components may well be a degenerate star. In order to investigate this latter possibility we have measured the UBV magnitudes and colors of the components of this binary system with the 24-inch Seyfert telescope. Techniques similar to those of Breckinridge and Kron (1964) were used to determine the UBV values. These techniques were?: (a) to observe the system as a composite source using a large sky diaphragm of about 22^ in diameter, and (¾) to measure the magnitude differences AV, ΔΒ, and AU between the two components using a small sky diaphragm of about 6" in diameter. Observations of type (a) could be made on nights of average seeing, while those of type (b) could be made on nights of excellent seeing. During October 1965, six observations of the composite kind and four separate observations of each star were secured. These have all been com- bined in Table I which gives the values oi V, Β — V, and U — B, for Stein 2051A and B. The measures have all been corrected for

TABLE I

UBV Observations of Stein 2051

Star v B-V U-B A 11.08 +1^65 +1^21 Β 12.44 0 .31 -0 .53

light scattered into the diaphragm from the excluded star. The scattered light amounted to between 1 and 3 percent of the excluded star's brightness, depending on seeing conditions, and was determined independently on each of the four nights by careful study of a bright single star located the appropriate distance from the diaphragm. The internal mean errors associated with each value of V, Β — V, and U — Β are ±0^02, =1=0^03, and ±0^04 respec- tively. If one assumes that Stein 2051 A is a normal unreddened star for its observed colors, then this star corresponds to about an M5 main-sequence star with a visual absolute magnitude of about 12.0

(Vyssotsky 1963). This value of Mv leads to a visual absolute magnitude of 13.3 for the companion star, B, and a distance modulus of —0.9 mag. The observed colors of Stein 2051 Β indicate that this star lies very near the black-body line in the Β — V, U — Β diagram, and is almost certainly a white dwarf. The visual absolute magni-

tude of star Β agrees fairly well with that found from the Mv, Β — V relation as given by Greenstein (1960). The distance modulus for the system implies a parallax of 0^15, which is in good agree- ment with the value of 0^13 given by Giclas et al*

REFERENCES

Breckinridge, J. Β., and Krön, G. Ε. 1964, Puh. A.S.P. 76, 139. Giclas, H. L., Bumham, R., and Thomas, N. G. 1965, Lowell Ohs. Bull. 6, 197 (No. 129). Greenstein, J. L. 1960, in Stellar Atmospheres, J. L. Greenstein, ed. (Chicago: University of Chicago Press), p. 688. Vyssotsky, A. N. 1963, in Basic Astronomical Dxña, Κ. Aa. Strand, ed. (Chi- cago: University of Chicago Press), p. 196.

* Editors note: See provisional measured parallax in this issue, Puh. A.S.P. 78, 167, 1966.