What happens when a black hole has a star for dinner?
In this new video, Melissa Hoffman of the National Radio Astronomy Observatory takes us on a tour of one of the most disruptive events in Universe: a black hole ripping apart a nearby star.
Astronomers call these stellar deaths tidal disruption events, and only a few of them have been observed.
Using radio and infrared telescopes, including the National Science Foundation’s Very Long Baseline Array (VLBA), in 2018 an international team of astronomers witnessed this event in a pair of colliding galaxies called Arp 299.
By creating protocells in hot, alkaline seawater, a UCL-led research
team has added to evidence that the origin of life could have been in
deep-sea hydrothermal vents rather than shallow pools.
experiments had failed to foster the formation of protocells – seen as a
key stepping stone to the development of cell-based life – in such
environments, but the new study, published in Nature Ecology & Evolution, finds that heat and alkalinity might not just be acceptable, but necessary to get life started.
are multiple competing theories as to where and how life started.
Underwater hydrothermal vents are among most promising locations for
life’s beginnings – our findings now add weight to that theory with
solid experimental evidence,” said the study’s lead author, Professor
Nick Lane (UCL Genetics, Evolution & Environment).
the Earth’s seas, there are vents where seawater comes into contact with
minerals from the planet’s crust, reacting to create a warm, alkaline
(high on the pH scale) environment containing hydrogen. The process
creates mineral-rich chimneys with alkaline and acidic fluids, providing
a source of energy that facilitates chemical reactions between hydrogen
and carbon dioxide to form increasingly complex organic compounds.
Some of the world’s oldest fossils, discovered by a UCL-led team, originated in such underwater vents.
researching the origins of life have made great progress with
experiments to recreate the early chemical processes in which basic cell
formations would have developed. The creation of protocells has been an
important step, as they can be seen as the most basic form of a cell,
consisting of just a bilayer membrane around an aqueous solution – a
cell with a defined boundary and inner compartment.
experiments to create protocells from naturally-occurring simple
molecules – specifically, fatty acids – have succeeded in cool, fresh
water, but only under very tightly controlled conditions, whereas the
protocells have fallen apart in experiments in hydrothermal vent
The study’s first author, Dr Sean Jordan (UCL
Genetics, Evolution & Environment), said he and his colleagues
identified a flaw in the previous work: “Other experiments had all used a
small number of molecule types, mostly with fatty acids of the same
size, whereas in natural environments, you would expect to see a wider
array of molecules.”
For the current study, the research team
tried creating protocells with a mixture of different fatty acids and
fatty alcohols that had not previously been used.
found that molecules with longer carbon chains needed heat in order to
form themselves into a vesicle (protocell). An alkaline solution helped
the fledgling vesicles keep their electric charge. A saltwater
environment also proved helpful, as the fat molecules banded together
more tightly in a salty fluid, forming more stable vesicles.
the first time, the researchers succeeded at creating self-assembling
protocells in an environment similar to that of hydrothermal vents. They
found that the heat, alkalinity and salt did not impede the protocell
formation, but actively favoured it.
“In our experiments, we have
created one of the essential components of life under conditions that
are more reflective of ancient environments than many other laboratory
studies,” Dr Jordan said.
“We still don’t know where life first
formed, but our study shows that you cannot rule out the possibility of
deep-sea hydrothermal vents.”
The researchers also point out that deep-sea hydrothermal vents are not unique to Earth.
Lane said: “Space missions have found evidence that icy moons of
Jupiter and Saturn might also have similarly alkaline hydrothermal vents
in their seas. While we have never seen any evidence of life on those
moons, if we want to find life on other planets or moons, studies like
ours can help us decide where to look.”
The study involved researchers from UCL and Birkbeck, University of London, and was funded by the BBSRC and bgC3.