COMMISSION 27 OF THE I. A. U.
        INFORMATION BULLETIN ON VARIABLE STARS
                     NUMBER 543

                              Konkoly Observatory
                              Budapest
                              1971 April 27



                  V 1057 Cyg


      Some preliminary spectroscopic information is now
available for the remarkable object V1057 Cygni = LkH_alpha-190,
Prior to 1969, the star was known only as one of the faint,
slightly variable (m_pg =15.5 - 16.5) T Tauri stars associated 
with the North America Nebula, NGC 7000 (Herbig, Ap.J.
128, 259, 1958). G. Welin discovered recently (Astr. and Ap.,
in press; private communication) that in late 1969 the star
had brightened to about, m_p = 10. It is still near that
brightness. 120-inch coude spectrograms obtained in March
and April 1971 show an absorption spectrum near type A1,
clearly more luminous than class V. The H_alpha line is rather
strongly in emission, with a P Cyg-type absorption component 
displaced about 420 km/sec to shortward. There is a
similarly-shifted component shortward of the K line of Ca II
but without accompanying emission. H_alpha and the infrared
Ca II triplet are the only emission lines detected. A very
interesting feature of the absorption spectrum is a rather
strong Li I Lambda6707 line, whose presence at type A1 implies a
high total lithium abundance.
      The only observation of the pre-outburst spectrum
of V1057 Cyg is apparently the low-dispersion Lick plate of
1957 Aug.3, which showed an advanced T Tauri-type emission
spectrum, with no detectable absorption lines. If the type
then had been K0, an increase in the surface brightness 
resulting from the change in the spectral type to A1 would
account for an increase in brightness by a factor 30 at
4200 A. Since the observed rise of approximately 5.5 mag,
corresponds to a factor of about 150, a radius increase of
only a factor 2.2 could account for the remainder. If the
original radius had been about 2 Sun, then in the rise time
of about 250 days (Wenzel, Mitt, Ver. Sterne, in press;
private communication), the photosphere would have had to
expand at a mean Velocity of only about 0.1 km/sec. This is
much less than the atmospheric ejection velocity of about
420 km/sec suggested by the P Cyg structure.
      The absorption-line velocity of V1057 Cyg is now
about -60 km/sec, clearly different from the mean velocity
of the H II region NGC 7000, which has been measured by
Courtes, Cruvellier, and Georgelin (J.d'Obs. 49, 329, 1966)
as about -15 km/sec, and by Miller (Ap.J. 151, 473, 1968)
as -19 +- 4 km/sec. The large apparent negative shift of the
star could be due to radial motion in its atmosphere but
if so, the magnitude of the velocity is again much greater
than expected.
      Welin also discovered that V1057 Cyg now appears
attached to a bright filament of nebulosity that was not
present before the outburst. This nebulosity is well seen
on recent 120-inch direct plates, and resembles a broken
ring about 50" x 90". The star is involved closely in still
brighter nebulosity, and is displaced from the center toward
the southwest edge of the ring. Presumably this ring, whose
appearance is rather like that of a cavity illuminated from
within, represents dust near the star that the just recently
been lit up as a result of brightening. At a distance of
500 parsecs, a light signal would expand in the plane of
the sky at the rate of 1" in 1.9 days. The portion of the
ring most distant from V1057 Cyg is about 65" east of the
star, and thus its illumination would be delayed by at least
190 days. This is compatible with the observed time of the
brightening of the star and the subsequent date of detection
of the nebulosity by Welin. It will be interesting to see
if still more distant reflection nebulosity appears as the
light signal continues to propagate outward.
      The outburst of V1057 Cyg is highly reminiscent of
the brightening of FU Orionis in 1939 (Herbig, Vistas in
Astr., 8, 109, 1966), even to details such as the sudden
appearance of a reflection nebula and to the high abundance
of lithium. If the two events represent the same basic.
phenomenon, then V1057 Cyg has established a very important
point that could not be settled in the case of FU Ori for
lack of a pre-outburst spectrogram. That is, the fact that
the spectrum of V1057 Cyg changed fundamentally from minimum 
to maximum light proves that an intrinsic change in the
star took place, and that the explanation is not that it was
simply unveiled by the dissipation of a circumstellar dust
cloud.
      We are very much indebted to Mr. Gunnar Welin for 
informing us in advance of publication of his very important
observations of V1057 Cyg and to Dr. W. Wenzel for information
on the light curve.

April 16, 1971

                         G.H. HERBIG
                         E.A. HARLAN
                       Lick Observatory
                    University of California
                  Santa Cruz, California 95060
                          U.S.A.