A METAL-RICH LOW-GRAVITY COMPANION TO A MASSIVE MILLISECOND PULSAR

Most millisecond pulsars with low-mass companions are in systems with either helium-core white dwarfs or non-degenerate ("black widow" or "redback") stars. A candidate counterpart to PSR J1816+4510 was identified by Kaplan et al. whose properties were suggestive of both types of...

Full description

Saved in:
Bibliographic Details
Published in:The Astrophysical journal 2013-03, Vol.765 (2), p.1-8
Main Authors: Kaplan, D L, Bhalerao, V B, van Kerkwijk, M H, Koester, D, Kulkarni, S R, Stovall, K
Format: Article
Language:English
Subjects:
ABSORPTION SPECTROSCOPY
ASTRONOMY
ASTROPHYSICS
ASTROPHYSICS, COSMOLOGY AND ASTRONOMY
Binary systems
CALCIUM
Calcium magnesium silicates
ECLIPSE
Eclipses
ELEMENT ABUNDANCE
EMISSION SPECTRA
EMISSION SPECTROSCOPY
GRAVITATION
HELIUM
HYDROGEN
MAGNESIUM
MASS
Millisecond pulsars
NEUTRON STARS
PULSARS
RADIAL VELOCITY
SILICON
STAR EVOLUTION
Stars
STELLAR ATMOSPHERES
WHITE DWARF STARS
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Most millisecond pulsars with low-mass companions are in systems with either helium-core white dwarfs or non-degenerate ("black widow" or "redback") stars. A candidate counterpart to PSR J1816+4510 was identified by Kaplan et al. whose properties were suggestive of both types of companions although identical to neither. We have assembled optical spectroscopy of the candidate companion and confirm that it is part of the binary system with a radial velocity amplitude of 343 + or - 7km s super(-1), implying a high pulsar mass, M sub(psr) sin super(3) i = 1.84 + or - 0.11 M sub([middot in circle]), and a companion mass Mc sin super(3) i = 0.193 + or - 0.012 M sub([middot in circle]), where i is the inclination of the orbit. The companion appears similar to proto-white dwarfs/sdB stars, with a gravity log sub(10)(g) = 4.9 + or - 0.3, and effective temperature 16,000 + or - 500 K. The strongest lines in the spectrum are from hydrogen, but numerous lines from helium, calcium, silicon, and magnesium are present as well, with implied abundances of roughly 10 times solar (relative to hydrogen). As such, while from the spectrum the companion to PSR J1816+4510 is superficially most similar to a low-mass white dwarf, it has much lower gravity, is substantially larger, and shows substantial metals. Furthermore, it is able to produce ionized gas eclipses, which had previously been seen only for low-mass, non-degenerate companions in redback or black widow systems. We discuss the companion in relation to other sources, but find that we understand neither its nature nor its origins. Thus, the system is interesting for understanding unusual stellar products of binary evolution, as well as, independent of its nature, for determining neutron-star masses.
ISSN:0004-637X
1538-4357
DOI:10.1088/0004-637X/765/2/158