Black Holes Have Simple Feeding Habits
At the center of spiral galaxy M81 is a supermassive black hole about 70 million times more massive than our sun.
A study using data from Chandra and ground-based telescopes, combined with detailed theoretical models, shows that the supermassive black hole in M81 feeds just like stellar mass black holes, with masses of only about ten times that of the sun. This discovery supports Einstein’s relativity theory that states black holes of all sizes have similar properties.
Image Credit: X-ray: NASA/CXC/Wisconsin/D.Pooley & CfA/A.Zezas; Optical: NASA/ESA/CfA/A.Zezas; UV: NASA/JPL-Caltech/CfA/J.Huchra et al.; IR: NASA/JPL-Caltech/CfA
Solar System Like Ours Discovered
Hidden in the huge amount of data gathered by the Kepler Telescope was the observation of a solar system a bit like our own, it consists of seven exoplanets arranged much like our own - rocky close in to the sun and gas giants further out. The system, KOI-351, was detected in early 2013 with three direct observations of planets with orbital periods of 59, 210 and 331 days. However, their orbital periods can vary by as much as 25.7 hours, which at first glance is a little strange. As all of the planets orbit within 1 astronomical unit (the distance of the Sun from the Earth) this variation was suspected to be due to tugs of as of yet unseen inner planets.
Using computer algorithms a team of scientists was able to detect four new planets in the system, bringing the total to seven. The four planets have orbital periods of 7, 9, 92 and 125 days thus making the system very compact. It is as of yet unknown why the system formed this way, and some scientists hypothesise that the system may be young and the planets may migrate outwards over the millions of years to come. It is hoped that an upcoming mission, PLATO, will receive funding and allow the scientists to have a second more detailed look at the system.
The color of the Aurora depends on the altitude and the atom being struck by solar radiation (causing excitation). At higher altitudes, there is more Atomic Oxygen than Nitrogen, leading to the common color stratifications you see.
500-200 km altitude
— Atomic Oxygen — Red
— Atomic Oxygen — Greenish-Yellow
— Ionized Nitrogen — Blue/Purple
— Nitrogen (N2) — Crimson
Oxygen only emits red at higher altitudes because once it’s excited, it takes a longer time to emit red than it does green. Why is that important? Well, at lower altitudes there is more Nitrogen for the Oxygen to bump into and absorb that excitation-energy before it gets a chance to emit red light. In this case, where the collision occurs, the Oxygen will emit Green and at low enough altitudes the Nitrogen-Oxygen collisions eventually prevent Oxygen from emitting any light at all.
During stronger storms, high energy solar particles will reach lower in the atmosphere and cause the Crimson emission from Nitrogen, creating a deep-red band at the lower edge of the aurora. Other elements emit light too, like Hydrogen (Blue) or Helium (Purple) which are at higher altitudes.
Valletta’s balconies in Malta.
THE WATERFALL NEBULA
The Waterfall Nebula, also known as Herbig-Haro 222 (HH-222), is located about 1,350 light-years away from Earth in the region of NGC 1999within the Great Orion Molecular Cloud complex. Herbig–Haro objects are small patches of nebulosity and are associated with newly born stars. The nebula’s elongated gas stream is about ten light years long and emits a variety of colours.
Scientists are unsure as to how the structure formed, though there are a number of hypotheses. One hypothesis suggests the gas filament is the result of the wind from a young star interacting with a molecular cloud nearby. This doesn’t explain why the main ‘stream’ of the waterfall and some fainter streams appear to converge on a bright and non-thermal radio source, which can be seen in the upper left of the curving structure.
Another hypothesis postulates that the structure’s unusual radio source comes from a binary system containing a hot white dwarf, neutron star, or black hole; the Waterfall may just be a jet from such a system. However, no x-rays have yet been detected and such systems are typically strong X-ray emitters. The origin of the Waterfall Nebula’s structure remains a mystery for now.
The red jet seen near the bottom of the image is called Herbig-Haro 34 (or HH 34). The bright regions within the lumpy gas are where various material is colliding with each other and heating up. The ‘blobby’ material within HH34 has a velocity of more than 700,000 kilometres per hour (more than 440,000 miles per hour).
Sources: 1, 2
Image Credit: Z. Levay (STScI/AURA/NASA), T.A. Rector (U. Alaska Anchorage) & H. Schweiker (NOAO/AURA/NSF), KPNO, NOAO