Astrophys.J.652:L97-L100,2006 We report on the identification of the lens responsible for microlensing
event MACHO-LMC-20. As part of a \textit{Spitzer}/IRAC program conducting
mid-infrared follow-up ...of the MACHO Large Magellanic Cloud microlensing fields,
we discovered a significant flux excess at the position of the source star for
this event. These data, in combination with high resolution near-infrared
\textit{Magellan}/PANIC data has allowed us to classify the lens as an early M
dwarf in the thick disk of the Milky Way, at a distance of $\sim 2$ kpc. This
is only the second microlens to have been identified, the first also being a M
dwarf star in the disk. Together, these two events are still consistent with
the expected frequency of nearby stars in the Milky Way thin and thick disks
acting as lenses.
1
A number of compounds were evaluated in an attempt to identify a κ‐opioid receptor agonist with limited access to the central nervous system.
2
Quaternary derivatives of the κ‐opioid agonists ...tifluadom, U‐50488H and ethylketocyclazocine were essentially devoid of opioid activity in a range of isolated tissue preparations.
3
A novel compound — ICI 204448 — is described which produced a potent and naloxone‐reversible inhibition of electrically‐evoked contraction of the guinea‐pig ileum, mouse vas deferens and rabbit vas deferens preparations. ICI 204448 was shown to displace the binding of the κ‐opioid ligand 3H‐bremazocine from guinea‐pig cerebellum membranes.
4
Ex vivo binding studies in mice showed ICI 204448 to be well absorbed following subcutaneous administration. The brain levels achieved by ICI 20448 were substantially lower than those produced by κ‐agonists such as U‐50488H and tifluadom.
5
A good correlation was found for a range of opioids between lipophilicity and degree of CNS penetration.
We have carried out photometry of the microlensing event MACHO-LMC-5 with
Spitzer's IRAC ten years after the magnification of the LMC source star was
recorded. This event is unique in the annals of ...gravitational microlensing: the
lensing star itself has been observed using HST (once with WFPC2 and twice with
ACS/HRC). Since the separation between the source and lens at the epoch of the
Spitzer observations was $\sim0.24''$, the two stars cannot be resolved in the
Spitzer images. However, the IRAC photometry clearly establishes that the lens
is a M5 dwarf star from its infrared excess, which in turn yields a mass of
$\sim0.2 M_{\odot}$. This demonstrates the potential of Spitzer to detect the
lenses in other gravitational microlensing events.
We report on the identification of the lens responsible for microlensing event MACHO-LMC-20. As part of a \textit{Spitzer}/IRAC program conducting mid-infrared follow-up of the MACHO Large Magellanic ...Cloud microlensing fields, we discovered a significant flux excess at the position of the source star for this event. These data, in combination with high resolution near-infrared \textit{Magellan}/PANIC data has allowed us to classify the lens as an early M dwarf in the thick disk of the Milky Way, at a distance of \(\sim 2\) kpc. This is only the second microlens to have been identified, the first also being a M dwarf star in the disk. Together, these two events are still consistent with the expected frequency of nearby stars in the Milky Way thin and thick disks acting as lenses.
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