A Thorne–Żytkow object (TŻO or TZO) is a type of star wherein a red giant or supergiant contains a neutron star at its core, formed from the collision of the giant with the neutron star. Such objects were hypothesized by Kip Thorne and Anna Żytkow in 1977. In 2014, it was discovered that the star HV 2112 was a strong candidate.
== Formation ==
A Thorne–Żytkow object is formed when a neutron star collides with a star, typically a red giant or supergiant. The colliding objects can simply be wandering stars. This is only likely to occur in extremely crowded globular clusters. Alternatively, ...
HD 140283, informally nicknamed Methuselah star, is a metal-poor subgiant star about 190 light years away from the Earth in the constellation Libra. Its apparent magnitude is 7.223. The star has been known to astronomers for over a century as a high-velocity star, and an early spectroscopic analysis by Chamberlain and Aller found it to have a substantially lower metal content than the Sun. Modern spectroscopic analyses find an iron content about a factor of 250 lower than that of the Sun. It is one of the closest Population II stars to us.
== Age and significance ==
Because HD 140283 is neither...
The magic SysRq key is a key combination understood by the Linux kernel, which allows the user to perform various low-level commands regardless of the system's state. It is often used to recover from freezes, or to reboot a computer without corrupting the filesystem. Its effect is similar to the computer's hardware reset button (or power switch) but with many more options and much more control.
This key combination provides access to powerful features for software development and disaster recovery. In this sense, it can be considered a form of escape sequence. Principal among the offered commands...
System request (often abbreviated SysRq or Sys Req) is a key on keyboards for PCs that has no standard use.
== History ==
Introduced by IBM with the PC/AT, it was intended to be available as a special key to directly invoke low-level operating system functions with no possibility of conflicting with any existing software. A special BIOS routine — software interrupt 0x15, subfunction 0x85 — was added to signal the OS when SysRq was pushed or released. Unlike most keys, when it is pressed nothing is stored in the keyboard buffer.
The specific low level function that the SysRq key was meant for was...
First, let us look at the rocket equation:
$$\Delta v=\ln \left(\frac{m_0}{m_f}\right)v_e$$
That tells how much a rocket can change its velocity. The requirements for a low orbit would increase on your heavier Earth. (For constant density it is proportional to the radius.)
How can we increase ...
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Your question is about the behavior of the Tsiolkovsky rocket equation itself, in the limit of very small final mass (dry mass). Roughly: "is there any limit to delta-v in theory?"
Using Mathjax:
$$
\Delta v=v_e ln\frac{m_0}{m_f}.
$$
If you just look at the velocity ratio and the mass ratio:
$$...
