Astronomy and Astrophysics – Astrophysics
Scientific paper
2008-06-13
Astronomy and Astrophysics
Astrophysics
Accepted for ApJ. 37 pages, including 8 figures
Scientific paper
10.1086/591050
Trigonometric parallax astrometry and BVI photometry are presented for two late-type subdwarf candidates, LSR1425+71 (sdM8.0) and LSR1610-00 (sd?M6pec). For the former we measure an absolute parallax of 13.37+/-0.51 mas yielding Mv=15.25+/-0.09. The astrometry for LSR1610-00 shows that this object is an astrometric binary with a period of 1.66+/-0.01 yr. The photocentric orbit is derived from the data; it has a moderate eccentricity (e ~ 0.44+/-0.02) and a semi-major axis of 0.28+/-0.01 AU based on our measured absolute parallax of 31.02+/-0.26 mas. Our radial velocity measure of -108.1+/-1.6 km/s for LSR1610-00 at epoch 2006.179, when coupled with the observation of -95+/-1 km/s at epoch 2005.167 by Reiners & Basri, indicates a systemic radial velocity of -101+/-1 km/s for the LSR1610-00AB pair. The galactic velocity components for LSR1425+71 and LSR1610-00AB -- (U,V,W)=(84+/-6, -202+/-13, 66+/-14) km/s and (U,V,W)=(36+/-2, -232+/-2, -61+/-2) km/s, respectively. For both stars, the velocities are characteristic of halo population kinematics. However, modeling shows that both stars have orbits around the galaxy with high eccentricity that pass remarkably close to the galactic center. LSR1425+71 has a luminosity and colors consistent with its metal-poor subdwarf spectral classification, while LSR1610-00 has a luminosity and most colors indicative of being only mildly metal-poor, plus a uniquely red B-V color. The companion to LSR1610-00 must be a low-mass, substellar brown dwarf. We speculate on the paradoxical nature of LSR1610-00 and possible sources of its peculiarities.
Canzian Blaise
Cushing Michael
Dahn Conard C.
Guetter Harry H.
Harris Hugh C.
No associations
LandOfFree
Trigonometric Parallaxes for Two Late-Type Subdwarfs: LSR1425+71 (sdM8.0) and the Binary LSR1610-00 (sd?M6pec) 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 Trigonometric Parallaxes for Two Late-Type Subdwarfs: LSR1425+71 (sdM8.0) and the Binary LSR1610-00 (sd?M6pec), we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Trigonometric Parallaxes for Two Late-Type Subdwarfs: LSR1425+71 (sdM8.0) and the Binary LSR1610-00 (sd?M6pec) will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-494740