Featured Research

from universities, journals, and other organizations

Hubble Separates Stars In The Mira Binary System

Date:
August 6, 1997
Source:
National Aeronautics And Space Administration
Summary:
Although the giant star Mira has been known for about 400 years, astronomers have had to wait for NASA's Hubble Space Telescope to provide the first ultraviolet images of the extended atmosphere of the cool red giant star and its nearby hot companion.

CONTACT: Donald Savage NASA Headquarters, Washington, DC (Phone: 202/358-1547)

Tammy Jones Goddard Space Flight Center, Greenbelt, MD (Phone: 301/286-5566)

Ray Villard Space Telescope Science Institute, Baltimore, MD (Phone: 410/338-4514)

Megan Watzke Harvard-Smithsonian Center for Astrophysics, Cambridge, MA (Phone: 617/495-7463)

Although the giant star Mira has been known for about 400years, astronomers have had to wait for NASA's Hubble Space Telescopeto provide the first ultraviolet images of the extended atmosphere ofthe cool red giant star and its nearby hot companion.

By giving astronomers a clear view of the individual members ofthis system, Hubble has provided valuable insights into other types ofdouble star systems where the stars are so close they interact with oneanother.

The separation between Mira and its companion is about 70 timesmore than that between Earth and the Sun, (equal to an angular size ofonly 0.6 arcseconds -- the apparent diameter of a dime at four milesaway) even smaller than the typically fuzzy ground-based telescopicimage of a single star as smeared out by Earth's turbulent atmosphere.

Using the European Space Agency's Faint Object Camera aboardHubble, Margarita Karovska and John Raymond of the Harvard-SmithsonianCenter for Astrophysics, Cambridge, MA; Warren Hack of the SpaceTelescope Science Institute, Baltimore, MD; and Edward Guinan ofVillanova University, Villanova, PA, obtained both ultraviolet andvisible light images and spectra of the two separate stars in the Mirasystem. The results appear in the June 20 Astrophysical JournalLetters.

In ultraviolet light, Hubble has resolved a small hook-likeappendage extending from Mira in the direction of the companion, whichmight be material from Mira being gravitationally drawn toward thesmaller star. Alternately, it could be material in Mira's upperatmosphere being heated due to the companion's presence.

Hubble's visible-light images show that Mira has an odd,asymmetrical shape resembling a football. This may be tied to dramaticchanges occurring during its expansion-contraction cycles, or to thepresence of unresolved spots on its surface. Hubble allows astronomersto measure the star's size at about 60 milliarcseconds, correspondingto a diameter some 700 times larger than our Sun. If Mira were at thecenter of our solar system, it would extend out more than 300 millionmiles, well beyond Mars' orbit and nearly two-thirds of the way toJupiter.

Mira (officially called Omicron Ceti in the constellation Cetus)is the prototype for an entire class of stars known as "Mira-typevariables." Although once like our Sun, Mira is now at the end of itslife, and has evolved into a cool red giant star that is highly variablein brightness. Contracting and expanding every 332 days, Mira shedsvast amounts of material through its powerful "wind" of gas and dust.

Mira's companion is a burned-out star called a white dwarf thatis surrounded by material captured from Mira's wind. At a distance ofabout 400 light-years, Mira is the closest wind-accreting binary systemto Earth.

Separating the spectra of Mira and its companion -- somethingastronomers previously have tried to do through indirect means -- is acrucial step for studies of physical processes associated with windaccretion in binaries.

Mira was discovered on August 13, 1596, by Dutch astronomerDavid Fabricus, who mistook it for a nova because it later faded fromview. He called it Mira, meaning "The Wonderful." Astronomers laterrealized it was really the first case of a variable star.

The Space Telescope Science Institute is operated by theAssociation of Universities for Research in Astronomy, Inc., for NASA,under contract with NASA's Goddard Space Flight Center, Greenbelt, MD. The Hubble Space Telescope is a project of international cooperationbetween NASA and the European Space Agency (ESA).

EDITORS NOTE: The Hubble images of Mira are available tomedia representatives by calling the Imaging Branch at NASAHeadquarters at 202/358-1900. Photo number is: (color) 97-HC-537

Image files in GIF and JPEG format and captions may be accessed on theInternet via anonymous ftp from oposite.stsci.edu in /pubinfo.

GIF JPEGPRC97-26 Mira gif/mira.gif jpeg/mira.jpg

Higher resolution digital versions (300 dpi JPEG) of the releasephotograph are available in /pubinfo/hrtemp: 97-26.jpg (color) and97-26bw.jpg (black & white).

GIF and JPEG images, captions and press release text are available viathe World Wide Web at URL:http://oposite.stsci.edu/pubinfo/PR/97/26.html and via links inhttp://oposite.stsci.edu/pubinfo/Latest.html orhttp://oposite.stsci.edu/pubinfo/Pictures.html

Space Telescope Science Institute press-release text and other information are available automatically when you subscribe to the STScI List Server. To subscribe, send e-mail to "listserv@stsci.edu". In the body of the message (not the subject line) type the words "subscribe pio Your Name". For example, someone named Jane Doe would type "subscribe pio Jane Doe". The system will respond with a confirmation of your subscription, and you will receive new press releases by e-mail.

* * * *


Story Source:

The above story is based on materials provided by National Aeronautics And Space Administration. Note: Materials may be edited for content and length.


Cite This Page:

National Aeronautics And Space Administration. "Hubble Separates Stars In The Mira Binary System." ScienceDaily. ScienceDaily, 6 August 1997. <www.sciencedaily.com/releases/1997/08/970806215931.htm>.
National Aeronautics And Space Administration. (1997, August 6). Hubble Separates Stars In The Mira Binary System. ScienceDaily. Retrieved September 15, 2014 from www.sciencedaily.com/releases/1997/08/970806215931.htm
National Aeronautics And Space Administration. "Hubble Separates Stars In The Mira Binary System." ScienceDaily. www.sciencedaily.com/releases/1997/08/970806215931.htm (accessed September 15, 2014).

Share This



More Space & Time News

Monday, September 15, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

NASA’s Curiosity Rover Finally Reaches Long-Term Goal

NASA’s Curiosity Rover Finally Reaches Long-Term Goal

Newsy (Sep. 15, 2014) — After more than two years, NASA’s Mars Curiosity Rover reached Mount Sharp, its long-term destination. Video provided by Newsy
Powered by NewsLook.com
SpaceX's Elon Musk Really Wants To Colonize Mars

SpaceX's Elon Musk Really Wants To Colonize Mars

Newsy (Sep. 14, 2014) — Elon Musk has been talking about his goal of colonizing Mars for years now, but how much of it does he actually have figured out, and is it possible? Video provided by Newsy
Powered by NewsLook.com
International Space Station Crew Returns Safely To Earth

International Space Station Crew Returns Safely To Earth

Newsy (Sep. 11, 2014) — The three-man crew touched down in Kazakhstan Wednesday after more than five months of science experiments in orbit. Video provided by Newsy
Powered by NewsLook.com
Solar Storm To Hit This Weekend, Scientists Not Worried

Solar Storm To Hit This Weekend, Scientists Not Worried

Newsy (Sep. 11, 2014) — Two solar flares which erupted in our direction this week will arrive this weekend. The resulting solar storm will be powerful but not dangerous. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins