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Hubble Exoplanet Search Field in Sagittarius

Hubble Exoplanet Search Field in Sagittarius

This is an image of one-half of the Hubble Space Telescope field of view in the Sagittarius Window Eclipsing Extrasolar Planet Search (SWEEPS). The field contains approximately 150,000 stars, down to 30th magnitude. The stars in the Galactic disk and bulge have a mixture of colors and masses. The field is so crowded with stars because Hubble was looking across 26,000 light-years of space in the direction of the center of our galaxy.

Half of these stars are bright enough for Hubble to monitor for any small, brief and periodic dips in brightness caused by the passage of an exoplanet passing in front of the star, an event called a transit. Hubble took approximately 520 pictures of this field, at red and blue wavelengths, from Feb. 22-29, 2004. The green circles identify 9 stars that are orbited by planets with periods of a few days. Planets so close to their stars with such short orbital periods are called "hot Jupiters."

These are considered "candidate" exoplanets because most of them are too faint to allow for spectroscopic observations that would allow for a precise measure of the planet's mass. The Hubble observations allow for a robust statistical estimate of the possible "false positives," which suggests that at least 45 percent of the candidates must be genuine planets.

The bottom frame identifies one of two stars in the field where astronomers were able to spectroscopically measure the star's back-and-forth wobble due to the pull of the planet. The planet turns out to be less than 3.8 Jupiter masses.

The members of the SWEEPS science team are Kailash C. Sahu, Stefano Casertano, Howard E. Bond, Jeff Valenti, T. Ed Smith, Mario Livio, Nino Panagia, Thomas M. Brown, Will Clarkson and Stephen Lubow (Space Telescope Science Institute), Dante Minniti and Manuela Zoccali (Universidad Catolica de Chile), Nikolai Piskunov (Uppsala University), Timothy Brown (High Altitude Observatory), Alvio Renzini (INAF-Osservatorio Astronomico di Padova), and R. Michael Rich (University of California at Los Angeles).

About the Object

  • R.A. Position
    R.A. PositionRight ascension – analogous to longitude – is one component of an object's position.
    17h 58m 59.99s
  • Dec. Position
    Dec. PositionDeclination – analogous to latitude – is one component of an object's position.
    -29° 12' 0.0"
  • Constellation
    ConstellationOne of 88 recognized regions of the celestial sphere in which the object appears.
    Sagittarius

About the Data

  • Data Description
    Data DescriptionProposal: A description of the observations, their scientific justification, and the links to the data available in the science archive.
    Science Team: The astronomers who planned the observations and analyzed the data. "PI" refers to the Principal Investigator.
    This image was created from HST data from proposal 9750: K. Sahu, and H. Bond (STScI), T. Brown (High Altitude Observatory, Boulder), S. Casertano and M. Livio (STScI), D. Minniti (Catholic University of Chile), N. Panagia (STScI), A. Renzini (Astronomical Observatory of Padova, Italy), R. Rich (University of California, Los Angeles), and M. Zoccali (Catholic University of Chile). The science team also includes J. Valenti, E. Smith, T. Brown, W. Clarkson, and S. Lubow (STScI), and N. Piskunov (Uppsala University, Sweden).
  • Instrument
    InstrumentThe science instrument used to produce the data.
    HST>ACS/WFC
  • Exposure Dates
    Exposure DatesThe date(s) that the telescope made its observations and the total exposure time.
    February 22 - 29, 2004, Exposure Time: 49 hours
  • Filters
    FiltersThe camera filters that were used in the science observations.
    F606W (V) and F814W (I)
  • Object Name
    Object NameA name or catalog number that astronomers use to identify an astronomical object.
    SWEEPS Field
  • Object Description
    Object DescriptionThe type of astronomical object.
    Stellar Field Near the Galactic Bulge
  • Release Date
    October 4, 2006
  • Science Release
    Hubble Finds Extrasolar Planets Far Across Galaxy
  • Credit
    NASA, ESA, K. Sahu (STScI) and the SWEEPS Science Team

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Hubble Exoplanet Search Field in Sagittarius
Color Info
Color InfoA brief description of the methods used to convert telescope data into the color image being presented.

This image is a composite of many separate exposures made by the ACS instrument on the Hubble Space Telescope using two different filters. Two filters were used to sample broad wavelength ranges. The color results from assigning different hues (colors) to each monochromatic image. In this case, the assigned colors are: Blue: F606W (V) Green: F606W (V) + F814W (I) Red: F814W (I)

Compass and Scale
Compass and ScaleAn astronomical image with a scale that shows how large an object is on the sky, a compass that shows how the object is oriented on the sky, and the filters with which the image was made.

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Details

Last Updated
Mar 28, 2025
Contact
Media

Claire Andreoli
NASA’s Goddard Space Flight Center
Greenbelt, Maryland
claire.andreoli@nasa.gov