Category Archives: Milky Way

An Update On Nova Del 2013 (PNVJ20233073+2046041) – Dimmer Views And A Distance Estimate

Posted on September 14, 2013 6:59 pm - - Leave a Comment

Greetings fellow astrophiles!

While the Night Sky is always inspiring, it is quite… constant. The positions of objects within our own Solar System change with respect to the background of stars, weather patterns on Jupiter and Saturn can produce a bit of variety for backyard telescopes, Iridium flares and other satellites produce some nice bursts of reflected sunlight, the Sun can prove to be a many-varied treat to afternoon solar watchers, and the most astute observers can pick out the differences in brightness of variable stars. That said, much of the rest of the Night Sky only changes due to the rotation of the Earth about its axis and the revolution of the Earth around the Sun (within the lifetimes of most observers, that is).

Significant changes to stars, nebulae, and galaxies can take decades, lifetimes, or eons, meaning even many observers take in the same deep sky views throughout their entire lives. The recent nova in Delphinus was then noteworthy as something that (1) changed dramatically over the course of days and (2) occurred within our own Milky Way galaxy. CNYO members held their first Scope Mob at Jamesville Beach to take in a prime view of the nova from just outside Syracuse, finding a quite reasonable spot for future sessions at the same time.

2013sept14_gif_1531x1459_2db958_zps3f68f105

“Animation of Possible Nova in Del by E. Guido & N. Howes,”
taken from s176.photobucket.com/…/gif_1531x1459_2db958_zps3f68f105.gif.html

With several excellent websites providing great detail on the nova itself (I specifically direct you to universetoday.com, space.com, and AstroBob’s article (link HERE), which I count as the most thorough article written on the event), a group of astronomers have provided an official measurement of the distance to Nova Del 2013, posted to Astronomers Telegram on 23 August. In their report, they determine that the nova is 4.2 kiloparsecs (I refer you to the wikipedia article on the parsec for more info), or about 13,700 light years, away. As our own galaxy is about 100,000 light years across and we’re about 25,000 light years from the center, this puts the nova in our own celestial neighborhood. That said, this means the nova itself occurred near the end of Beringia, the land at the bottom of the Bering Strait, after the last great ice retreat but before the flooding that separated Asia from America (so it’s been a while, but an eye blink in celestial terms).

A snippet of the abstract that includes the reported distance estimate is reproduced below from the original post, which can be found at: www.astronomerstelegram.org/?read=5313

Distance of nova Del 2013 from MMRD relations

ATel #5313; M. M.M. Santangelo, M. Pasquini, S. Gambogi, G. Cavalletti (OAC – Osservatorio Astronomico di Capannori and IRF – Istituto Ricerche Fotometriche, Italy)
on 23 Aug 2013; 15:56 UT
Credential Certification: Filippo Mannucci (filippo@arcetri.astro.it)

Subjects: Optical, Nova

… So the distance of the nova is d ~ 4.2 +/- 0.4 kpc Using the linear Mv-log(t2) relation of Downes & Duerbeck (2000, AJ 120, p.2007) a t2 = 8.5 implies an absolute magnitude of Mv ~ -8.9 +/- 0.2. So, ceteris paribus, the distance changes to d ~ 3.5 +/- 0.4 kpc. As a final preliminary estimate, we can adopt a value around 4 kpc (or a bit less) for the distance of the nova DEL 2013.

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NASA News – Herschel Finds Star Possibly Making Planets Past Its Prime

Posted on January 30, 2013 11:19 pm - - Leave a Comment

Above: This artist’s concept illustrates an icy planet-forming disk around a young star called TW Hydrae, located about 175 light-years away in the Hydra, or Sea Serpent, constellation. Image credit: NASA/JPL-Caltech.

From NASA News: RELEASE: 13-036 – 30 January 2013

WASHINGTON — A star thought to have passed the age at which it can form planets may in fact be creating new worlds. The disk of material surrounding the surprising star called TW Hydrae may be massive enough to make even more planets than we have in our own solar system.

The findings were made using the European Space Agency’s Herschel Space Telescope, a mission in which NASA is a participant.

At roughly 10 million years old and 176 light years away, TW Hydrae is relatively close to Earth by astronomical standards. Its planet-forming disk has been well studied. TW Hydrae is relatively young but, in theory, it is past the age at which giant plants already may have formed.

“We didn’t expect to see so much gas around this star,” said Edwin Bergin of the University of Michigan in Ann Arbor. Bergin led the new study appearing in the journal Nature. “Typically stars of this age have cleared out their surrounding material, but this star still has enough mass to make the equivalent of 50 Jupiters,” Bergin said.

In addition to revealing the peculiar state of the star, the findings also demonstrate a new, more precise method for weighing planet-forming disks. Previous techniques for assessing the mass were indirect and uncertain. The new method can directly probe the gas that typically goes into making planets.

Planets are born out of material swirling around young stars, and the mass of this material is a key factor controlling their formation. Astronomers did not know before the new study whether the disk around TW Hydrae contained enough material to form new planets similar to our own.

“Before, we had to use a proxy to guess the gas quantity in the planet-forming disks,” said Paul Goldsmith, the NASA project scientist for Herschel at NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, Calif. “This is another example of Herschel’s versatility and sensitivity yielding important new results about star and planet formation.”

Using Herschel, they were able to take a fresh look at the disk with the space telescope to analyze light coming from TW Hydrae and pick out the spectral signature of a gas called hydrogen deuteride. Simple hydrogen molecules are the main gas component of planets, but they emit light at wavelengths too short to be detected by Herschel. Gas molecules containing deuterium, a heavier version of hydrogen, emit light at longer, far-infrared wavelengths that Herschel is equipped to see. This enabled astronomers to measure the levels of hydrogen deuteride and obtain the weight of the disk with the highest precision yet.

“Knowing the mass of a planet-forming disk is crucial to understanding how and when planets take shape around other stars,” said Glenn Wahlgren, Herschel program scientist at NASA Headquarters in Washington.

Whether TW Hydrae’s large disk will lead to an exotic planetary system with larger and more numerous planets than ours remains to be seen, but the new information helps define the range of possible planet scenarios.

“The new results are another important step in understanding the diversity of planetary systems in our universe,” said Bergin. “We are now observing systems with massive Jupiters, super-Earths, and many Neptune-like worlds. By weighing systems at their birth, we gain insight into how our own solar system formed with just one of many possible planetary configurations.”

Herschel is a European Space Agency (ESA) cornerstone mission, with science instruments provided by a consortium of European institutes and with important participation by NASA. NASA’s Herschel Project Office is based at JPL, which contributed mission-enabling technology for two of Herschel’s three science instruments. NASA’s Herschel Science Center, part of the Infrared Processing and Analysis Center at the California Institute of Technology (Caltech) in Pasadena, supports the United States astronomical community. Caltech manages JPL for NASA.

For NASA’S Herschel website, visit: http://www.nasa.gov/herschel

For ESA’S Herschel website, visit: http://www.esa.int/SPECIALS/Herschel/index.html

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