Optical observations of Dwingeloo 1, a nearby barred spiral galaxy behind the Milky Way

Brosch, N.; Almoznino, E.; Assendorp, R.; Kraan-Korteweg, R. C.; Balcells, M.; Lahav, O.; Maddox, S. J.; Loan, A. J.; Goldberg, E.; Ofek, E. O.
Bibliographical reference

Monthly Notices of the Royal Astronomical Society, Volume 280, Issue 2, pp. 537-549.

Advertised on:
5
1996
Number of authors
10
IAC number of authors
0
Citations
9
Refereed citations
9
Description
We present new optical observations of the nearby barred spiral galaxy Dwingeloo 1 (Dw1) obtained with the Isaac Newton, William Herschel and Wise telescopes. Dw1 lies at Galactic coordinates (l=138.˚52, b=-0.˚11) and it is heavily obscured by dust and gas in the Milky Way. We infer that Dw1 is of morphological type SBb or SBc (T=4), has an inclination i~=50 deg, a position angle PA~=110 deg, and a recession velocity relative to the Milky Way V_MW=256+/-9 km s^-1. The measured total apparent magnitudes of Dw1 are V=14.0+/-0.5, R=12.2+/-0.2 and I=10.7+/-0.2. The extinction estimate towards Dw1 is highly uncertain. The extinction in the B band, derived from Galactic HI column density measurements, is A_B~=5.8. Estimated from Galactic 100-μm emission, the extinction is A_B~=4.3, while the reddened colours of Dw1 yield an estimate of A_B~=10.4. Assuming A_B=5.8, Tully-Fisher relations in the I and R bands lead to a distance estimate for Dw1 of D~=300 km s^-1. However, for the derived range of extinction estimates 4.3<~A_B<~10.4, the distance varies from 100 to 500 km s^-1. We also report the detection of numerous HII regions associated with Dw1, and present data from the Infrared Astronomical Satellite (IRAS) archive.