Tag Archives: University of Rochester

star flyby oort cloud

70,000 Years Ago, a Rogue Star Passed Through Our Solar System

Too close for comfort – a team of astronomers from the US, Europe, Chile and South Africa concluded that a dim star passed through the Oort cloud, our solar system’s distant cloud of comets. The star missed the Earth by less than one light year, and passed five times closer than the current closest star, Proxima Centauri.

star flyby oort cloud

Artist’s conception of Scholz’s star and its brown dwarf companion (foreground) during its flyby of the solar system 70,000 years ago. The Sun (left, background) would have appeared as a brilliant star. The pair is now about 20 light years away.
Credit: Michael Osadciw/University of Rochester.

In a paper published in The Astrophysical Journal Letters, lead author Eric Mamajek from the University of Rochester and his team studied the velocity and trajectory of a low-mass star system – WISE 0720-0846 (nicknamed “Scholz’s star”). Due to its low luminosity, the star was discovered only a year ago by astronomer Ralf Dieter-Scholz in Potsdam, Germany, through the use of NASA’s WISE (Wide Field Infrared Survey Explorer), which mapped the entire sky in infrared during the years 2010 and 2011.

Since it was discovered, it had some interesting characteristics. despite being fairly close (“only” 20 light years away), it showed very slow tangential motion, that is, motion across the sky. By studying its trajectory and velocity, astronomers found that the star was either moving towards, or away from our solar system. They reconstructed its past movement and quickly realized it was moving away from our solar system, which means that it passed through it (or very close to it) sometime in the past.

“Most stars this nearby show much larger tangential motion,” says Mamajek, associate professor of physics and astronomy at the University of Rochester. “The small tangential motion and proximity initially indicated that the star was most likely either moving towards a future close encounter with the solar system, or it had ‘recently’ come close to the solar system and was moving away. Sure enough, the radial velocity measurements were consistent with it running away from the Sun’s vicinity — and we realized it must have had a close flyby in the past.”

Scholz’s star moved much faster than expected, and missed Earth by “a whisker” – in astronomical terms, that is. It passed roughly 0.8 light years away from Earth, at 8 trillion kilometers; this happened 70,000 years ago. It may seem like a lot, but it’s really too close for comfort. This fits with an earlier theory, which proposed that such close flybys take place every 100,000 years or so. These encounters could hit the Oort cloud and trigger “comet showers” in the solar system.

“Sure enough, the radial velocity measurements were consistent with it running away from the sun’s vicinity — and we realized it must have had a close flyby in the past,” Mamajek said in a news release.

 

The star is a rogue star – a star that has escaped the gravitational pull of its home galaxy and is moving independently in or towards the intergalactic void; the movement of rogue stars is often hard to predict. A 2012 study claimed that rogue planets riddle the Milky Way, and while rarer, there are also rogue stars in our galaxy.

Currently, Scholz’s star is a small, inconspicuous red dwarf in the constellation of Monoceros, about 20 light years away. The star is part of a binary star system, composed of a low-mass red dwarf star (with mass about 8% that of the Sun) and a “brown dwarf” companion (with mass about 6% that of the Sun). Red dwarfs are by far the most common type of star in the Milky Way, at least in the neighborhood of the Sun, but due to their low luminosity, they are difficult to observe and study. Brown stars are “failed stars” – substellar objects not massive enough to sustain hydrogen-1 fusion reactions in their cores, unlike … well, stars.

Journal Reference:

  1. Eric E. Mamajek, Scott A. Barenfeld, Valentin D. Ivanov, Alexei Y. Kniazev, Petri Väisänen, Yuri Beletsky, Henri M. J. Boffin. THE CLOSEST KNOWN FLYBY OF A STAR TO THE SOLAR SYSTEM. The Astrophysical Journal, 2015; 800 (1): L17 DOI: 10.1088/2041-8205/800/1/L17

 

Super hydrophobic surface

Laser-etching pattern turns any metal into a super-hydrophobic surface

A new generation of water-repellent products could be just ahead after researchers at University of Rochester demonstrated an amazing laser technique that etches tiny micro and nano grooves into a metal surface making it super-hydrophobic. As you can notice, the surface becomes so strongly repelled to water than the water molecules literally bounce off until they exit the surface altogether. We’ve seen such demonstrations before, but previous attempts relied on chemical coatings. Because the nano geometrical pattern is etched in the metal, it does not wear off.

Bouncy water molecules

Super hydrophobic surface

Credit: University of Rochester // GIF via Sploid

“The material is so strongly water-repellent, the water actually gets bounced off. Then it lands on the surface again, gets bounced off again, and then it will just roll off from the surface,” said Rochester’s Chunlei Guo , professor of optics.

Previously, Guo and colleagues had used a similar laser-patterning technique that turned metals black. Building-up on this previous research, the team investigated what kind of properties metals would gain if certain intricate patterns of micro- and nanoscale structures were etched with high-power lasers.

Metal surfaces etched this way could be built in aircraft fuselage to reduce drag or built-in the next generation Teflon cookery. Teflon is also hydrophobic, but the difference is that to make water to roll-off a Teflon coated material, you need to tilt the surface to nearly a 70-degree angle before the water begins to slide off. You can make water roll off Guo’s metals by tilting them less than five degrees.

superhydrophobic surface metal

Credit: University of Rochester // GIF via Sploid

Of more practical worth would be implementing it in developing countries to store more water and build more hygienic latrines.

“In these regions, collecting rain water is vital and using super-hydrophobic materials could increase the efficiency without the need to use large funnels with high-pitched angles to prevent water from sticking to the surface,” says Guo. “A second application could be creating latrines that are cleaner and healthier to use.”

The researchers claim because there’s no chemical coating, the hydrophobic layer won’t rob off. But what about dust and other impurities gathering in the tiny etched grooves? According to the team, this isn’t a problem. The surface also  collects dust particles and takes them along for the ride. In tests, ordinary dust from a vacuum cleaner was applied to the surface; with only three drops of water, half of the dust particles were removed. It’s still not certain how expensive hydrophobic metal surfaces would be. Nevertheless, it’s a pretty exciting project.

Findings appeared in the Journal of Applied Physics.

"Adaptive behavioral prioritization requires flexible outputs from fixed neural circuits. In C. elegans, the prioritization of feeding versus mate searching depends on biological sex (males will abandon food to search for mates, whereas hermaphrodites will not) as well as developmental stage and feeding status. Previously, we found that males are less attracted than hermaphrodites to the food-associated odorant diacetyl, suggesting that sensory modulation may contribute to behavioral prioritization," the researchers write in Current Biology. Image: Current Biology.

Males may be Wired to choose Sex over Food

Men are from Mars and women are from Venus, or so the old adage goes, but how different are men and women? I won’t go into debates like whether or not men and women are neurologically the same – it’s a far too exhaustive and exhausting subject for such a short article. Clearly, however, men and women are different in biological terms, and going beyond physical differences, there are numerous hormonal interactions that greatly vary between men and women. For instance, men may be wired to go to greater lengths than women to have sex, if we’re to judge from the findings of a recent study which found male roundworms would rather mate than gobble food.

Sex or food? It might not be a matter of opinion

"Adaptive behavioral prioritization requires flexible outputs from fixed neural circuits. In C. elegans, the prioritization of feeding versus mate searching depends on biological sex (males will abandon food to search for mates, whereas hermaphrodites will not) as well as developmental stage and feeding status. Previously, we found that males are less attracted than hermaphrodites to the food-associated odorant diacetyl, suggesting that sensory modulation may contribute to behavioral prioritization," the researchers write in Current Biology. Image: Current Biology.

“Adaptive behavioral prioritization requires flexible outputs from fixed neural circuits. In C. elegans, the prioritization of feeding versus mate searching depends on biological sex (males will abandon food to search for mates, whereas hermaphrodites will not) as well as developmental stage and feeding status. Previously, we found that males are less attracted than hermaphrodites to the food-associated odorant diacetyl, suggesting that sensory modulation may contribute to behavioral prioritization,” the researchers write in Current Biology. Image: Current Biology.

Both feeding and mating are deeply etched into our biology, being essential to survival and reproduction, so choosing between the two can be a tough judgement call. Simple, yet subtle changes to the brain circuitry can make this decision easier, according to the findings of a group of researchers at University of Rochester published in Current Biology.

“While we know that human behavior is influenced by numerous factors, including cultural and social norms, these findings point to basic biological mechanisms that may not only help explain some differences in behavior between males and females, but why different sexes may be more susceptible to certain neurological disorders,” lead author Douglas Portman said in a press release.

The researchers studied Caenorhabditis elegans, a type of microscopic roundworm and favorite lab pet for researchers studying anything from genetics, to diseases, to immortality. It’s important to note that there isn’t a clear distinction between males and females when C. elegans is concerned. The females are actually hermaphrodites, meaning they’re able to self-fertilize, but that doesn’t necessarily stop them from seeking mating partners in males, and as such are considered to be modified females.

The team focused on the roundworm’s sense of smell, which they used to probe their suspicions that male and females are wired differently. The Rochester researchers placed hermaphrodites in the center of a petri dish with some food, with an additional ring of tempting food surrounding them – an obstacle for the males placed at the edge of the dish. The males either had a normal genetic profile – the control group – or overexpressed the chemoreceptor ODR-10, related to the worms’ sense of smell and found to control their decision between food and sex.

The normal males made a B-line for the hermaphrodites at the center of the dish. The hermaphrodites produce ODR-10 receptors, making them more sensitive to food, which explains why they didn’t stray from their food, unlike the males. Given the choice between overexpressing ODR-10 and maintaining normal levels, males opted for the latter 10 to one, researchers say. The findings rang true to the researchers’ predictions – males prefer sex over food. At least male worms, but are we humans any different? This is definitely a lot harder to test, but the conclusions are nonetheless very interesting.