Sagittarius Window Eclipsing Extrasolar Planet Search

Detail image with exoplanet locations indicated with green circles.
Organization	NASA / ESA / STSci
Alternative names	SWEEPS
Wavelength	350-1100 nm
Data sources	Hubble Space Telescope Advanced Camera for Surveys - Wide Field Channel
Goals	Search for exoplanets in the Milky Way's central bulge
Data products	16 candidate planets (Nos 1-16) are found around 16 stars (format JHHMMSS.ss+DDMMSS.s)[1]

The Sagittarius Window Eclipsing Extrasolar Planet Search, or SWEEPS, was a 2006 astronomical survey project using the Hubble Space Telescope's Advanced Camera for Surveys - Wide Field Channel to monitor 180,000 stars for seven days to detect extrasolar planets via the transit method.^[1]

Area examined

SWEEPS search area.

SWEEPS search area detail.

The stars that were monitored in this astronomical survey were all located in the Sagittarius-I Window,^[2] a rare transparent view to the Milky Way's central bulge stars in the Sagittarius constellation as our view to most of the galaxy's central stars is blocked by lanes of dust.^[3] These stars in the galaxy's central bulge region are approximately 27,000 light years from Earth.^[2]

Planets discovered

Sixteen candidate planets were discovered with orbital periods ranging from 0.6 to 4.2 days. Planets with orbital periods less than 1.2 days have not previously been detected, and have been dubbed "ultra-short period planets" (USPPs) by the search team. USPPs were discovered only around low-mass stars, suggesting that larger stars destroyed any planets orbiting so closely or that planets were unable to migrate as far inward around larger stars.^[4]

Planets were found with roughly the same frequency of occurrence as in the local neighborhood of Earth.^[2]

SWEEPS-4 and SWEEPS-11 orbited stars that were sufficiently visually distinct from their neighbors that follow-up observations using the radial velocity method were possible, allowing their masses to be determined.^[2]

This table is constructed from information obtained from the Extrasolar Planets Encyclopedia and SIMBAD databases that reference the Nature article as their source.^[4]

Star	Constellation	Right ascension	Declination	App. mag.	Distance (ly)	Spectral type	Planet	Mass (MJ)	Radius (RJ)	Orbital period (d)	Semimajor axis (AU)	Orbital eccentricity	Inclination (°)	Discovery year
SWEEPS J175853.29-291233.5	Sagittarius	17^h 58^m 53^s	−29° 12′ 33″	22.2	~22000		SWEEPS-01	?	1.01	1.56	0.025	?	86+	2006
SWEEPS J175853.38-291217.8	Sagittarius	17^h 58^m 53^s	−29° 12′ 18″	25.1	~22000		SWEEPS-02	?	1.37	0.912	0.015	?	86+	2006
SWEEPS J175853.57-291144.1	Sagittarius	17^h 58^m 53^s	−29° 11′ 44″	22.5	~22000		SWEEPS-03	?	0.87	1.27	0.021	?	86+	2006
SWEEPS J175853.92−291120.6	Sagittarius	17^h 58^m 54^s	−29° 11′ 21″	18.8	~22000		SWEEPS-04	<3.8	0.81	4.2	0.055	?	87+	2006
SWEEPS J175854.60-291128.2	Sagittarius	17^h 58^m 55^s	−29° 11′ 28″	23.9	~22000		SWEEPS-05	?	1.09	2.313	0.030	?	87+	2006
SWEEPS J175857.29-291253.4	Sagittarius	17^h 58^m 57^s	−29° 12′ 53″	19.5	~22000		SWEEPS-06	?	0.82	3.039	0.042	?	86+	2006
SWEEPS J175857.69-291114.5	Sagittarius	17^h 58^m 58^s	−29° 11′ 15″	21.5	~22000		SWEEPS-07	?	0.9	1.747	0.027	?	86+	2006
SWEEPS J175859.24-291328.7	Sagittarius	17^h 58^m 59^s	−29° 13′ 29″	21.7	~22000		SWEEPS-08	?	0.98	0.868	0.017	?	84+	2006
SWEEPS J175859.60-291211.8	Sagittarius	17^h 59^m 00^s	−29° 12′ 12″	22.5	~22000		SWEEPS-09	?	1.01	1.617	0.025	?	86+	2006
SWEEPS J175902.00-291323.7	Sagittarius	17^h 59^m 02^s	−29° 13′ 24″	26.2	~22000		SWEEPS-10	?	1.24	0.424	0.008	?	84+	2006
SWEEPS J175902.67−291153.5	Sagittarius	17^h 59^m 03^s	−29° 11′ 54″	19.83	~22000		SWEEPS-11	9.7	1.13	1.796	0.03	?	84+	2006
SWEEPS J175904.44-291317.1	Sagittarius	17^h 59^m 04^s	−29° 13′ 17″	21.8	~22000		SWEEPS-12	?	0.91	2.952	0.038	?	87+	2006
SWEEPS J175905.95-291305.6	Sagittarius	17^h 59^m 04^s	−29° 13′ 17″	21.38	~22000		SWEEPS-13	?	0.78	1.684	0.027	?	86+	2006
SWEEPS J175907.56-291039.8	Sagittarius	17^h 59^m 04^s	−29° 13′ 17″	22.38	~22000		SWEEPS-14	?	0.93	2.965	0.037	?	87+	2006
SWEEPS J175907.64-291023.7	Sagittarius	17^h 59^m 04^s	−29° 13′ 17″	25.66	~22000		SWEEPS-15	?	1.37	0.541	0.010	?	84+	2006
SWEEPS J175908.44-291140.6	Sagittarius	17^h 59^m 08^s	−29° 11′ 41″	23.78	~22000		SWEEPS-16	?	1.4	0.969	0.017	?	85+	2006

See also

• Baade's Window
• Optical Gravitational Lensing Experiment or OGLE also examines the galactic bulge for planets.

References

1. "SIMBAD Details on Acronym: SWEEPS". SIMBAD. Centre de Données astronomiques de Strasbourg. Retrieved 2009-05-21.
2. Sahu, K. C.; et al. (2007). "Planets in the Galactic Bulge: Results from the SWEEPS Project". ASP Conference Series. 393: 93. arXiv:0711.4059. Bibcode:2008ASPC..398...93S.
3. Piotr Popowski; Kem Cook; Andrew Becker (December 2003). "The Large-Scale Extinction Map Of The Galactic Bulge From The MACHO Project Photometry". The Astronomical Journal. 126 (6): 2910–2921. arXiv:astro-ph/0303075. Bibcode:2003AJ....126.2910P. doi:10.1086/379291.
4. Sahu, K. C.; et al. (2006). "Transiting extrasolar planetary candidates in the Galactic bulge". Nature. 443 (7111): 534–540. arXiv:astro-ph/0610098. Bibcode:2006Natur.443..534S. doi:10.1038/nature05158. PMID 17024085.

External links

• News Release Number: STScI-2006-34 Hubble Finds Extrasolar Planets Far Across Galaxy