Astronomy and Astrophysics – Astrophysics
Scientific paper
2001-05-21
Astronomy and Astrophysics
Astrophysics
aastex, 37 pages, 13 (reduced resolution) .ps figures. Accepted by AJ. Full resolution figures are available upon request to t
Scientific paper
10.1086/322104
We present HST photometry of the resolved stellar population in the dwarf irregular galaxy NGC 1705. The galaxy has been observed with both WFPC2 and NICMOS, and successful images have been obtained in the F555W, F814W, F110W and F160W bands. The optical fields cover most of the galaxy, while the infrared field (NIC2) maps only its central regions. The optical photometry provides \~20000 objects down to m_F555W ~ 29 in the PC field of view and ~ 20000 in the three WFCs. In the infrared we have been able to resolve ~ 2400 stars down to m_{F110W}, m_{F160W} ~ 26. A subsample of 1834 stars have been unambiguously measured in all the four bands. The corresponding color-magnitude diagrams (CMDs) confirm the existence of an age gradient, showing that NGC 1705 hosts both young (a few Myr old) and very old (up to 15 Gyr old) stars, with the former strongly concentrated toward the galactic center and the latter present everywhere, but much more easily visible in the external regions. The tip of the red giant branch (TRGB) is clearly visible both in the optical and in the infrared CMDs and allows us to derive the galaxy distance. Taking into account the uncertainties related to both the photometry and the TRGB magnitude -- distance relation, we find that the distance modulus of NGC 1705 is (m-M)_0=28.54 +- 0.26, corresponding to a distance D=5.1 +- 0.6 Mpc.
Aloisi Alessandra
Bellazzini Michele
Greggio Laura
Leitherer Cl.
Montegriffo Paolo
No associations
LandOfFree
The Resolved Stellar Populations in NGC 1705 does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with The Resolved Stellar Populations in NGC 1705, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and The Resolved Stellar Populations in NGC 1705 will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-563861