HD 1461 / HR 72

Steven Vogt,
UCSC,




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HD 1461
is located
northeast of
the bright
orange giant
Deneb Kaitos,
(Beta Ceti) in
Constellation
Cetus (more).

Today, some astronomers now refer to this star as HD 1461, as it is listed in the Henry Draper (1837-82) Catalogue with extension (HDE), a massive photographic stellar spectrum survey carried out by Annie Jump Cannon (1863-1941) and Edward Charles Pickering (1846-1919) from 1911 to 1915 under the sponsorship of a memorial fund created by Henry's wife, Anna Mary Palmer. As a relatively bright star in Earth's night sky, the star is also catalogued as Harvard Revised (HR) 72, a numbering system derived from the 1908 Revised Harvard Photometry catalogue of stars visible to many Humans with the naked eye which has been revised and expanded through its successor, the Yale Bright Star Catalogue through the hard work of the late E. Dorrit Hoffleit (1907 - 2007) and others. The star was also designated as BD-08 38 in a catalogue that was originally published in 1863 by Friedrich Wilhelm August Argelander (1799-1875) on the position and brightness of 324,198 stars between +90° and -2° declination that were measured over 11 years from Bonn, Germany with his assistants Eduard Schönfeld (1828-1891) and Aldalbert Krüger (1832-1896), which became famous as the Bonner Durchmusterung ("Bonn Survey") and is typically abbreviated as BD.

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	Orbital Distance (a=AUs)	Orbital Period (P=years)	Orbital Eccentricity (e)	Orbital Inclination (i=degrees)	Mass (Earths)	Diameter (Earths)	Density (Earths)	Surface Gravity (Earths)	Metallicity (Solar)
61 Vir	0.0	...	...	...	337,000-347,000	120	...	...	1.5-1.6
Planet "b"	0.063	0.016	~0	?	=>6.94	>1	...	...	...
Planet "c"	0.112	0.037	~0	?	=>5.92	>1	...	...	...
Inner H.Z. Edge?	0.775	0.666	0	?	...	...	...	...	...
Planet "d?"	1.16	1.28	0.74+/-13	?	=>27.9	>4	...	...	...
Outer H.Z. Edge?	1.55	1.883	0	?	...	...	...	...	...
Planet "e?"	~5	13.7	0.16+/0.29	?	=>87.1	>8	...	...	...

The Star

HD 1461 is a yellow-orange main sequence dwarf of spectral and luminosity type G0 V (Cenarro et al, 2007), but it has been classed as orange as G5 and as bright as a subgiant. The star has about 1.02 to 1.08 percent of Sol's mass (95 percent using the isochrone mass estimate of Valenti and Fischer, 2005; Takeda et al, 2007; Sousa et al, 2008; and NASA Star and Exoplanet Database, based on David F. Gray, 1992), 1.1 times of its diameter (Valenti and Fischer, 2005; and Takeda et al, 2007), and around 1.2 times of its theoretical bolometric luminosity (Sousa et al, 2008; Valenti and Fischer, 2005; NASA Star and Exoplanet Database, based on Kenneth R. Lang, 1980). The star may be 1.5 to 1.6 times as enriched as Sol with elements heavier than hydrogen ("metallicity"), based on its abundance of iron (Sousa et al, 2008; Cenarro et al, 2007; Valenti and Fischer, 2005; and NASA Star and Exoplanet Database. It appears to be 4.2 to 7.1 billion years in age (Takeda et al, 2007; Valenti and Fischer, 2005; and (Wright et al, 2004). HD 1461 appears to be relatively inactive (Rivera et al, 2009). The star has a rotational period of 29 days (Wright et al, 2004). Useful star catalogue numbers for the star include: HR 72, Gl 16.1, Hip 1499, HD 1461, BD-08 38, SAO 128690, GJ 9009, Wo 9009, LTT 149, and GC 378.

Habitable Zone

Planetary System

Planet "b" - On December 14, 2009, a team of astronomers (including Eugenio J. Rivera, R. Paul Butler, Steven S. Vogt; Gregory Laughlin, Gregory W. Henry, and Stefano Meschiari) announced the discovery of at least one super-Earth and possibly two additional planets, based on radial-velocity observations with the Keck Observatory's High Resolution Echelle Spectrometer (HIRES) and the Anglo-Australian Telescope (U.C. Santa Cruz news release; Keck press release; and Rivera et al, 2009). The innermost planetary candidate "b" was initially estimated to have at least 7.6 Earth-masses, but this estimate was revised to at least 6.94 Earth-masses in 2011 (Mayor et al, 2011, Table 3; and Segransan et al, 2011, in preparation). Planet b orbits HD 1461 at an average orbital distance of 0.063 AU with a period of 5.77 days, with an eccentricity initially estimated at around e= 0.04 +/-0.01.

Trent Schindler, NSF


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(more images and videos).



Planets "b" and "c" are super-Earth candidates,
which may be hot and rocky planets outside of
the star's habitable zone, like Gl 876 d as
imagined by Schindler (more).

Planet "c" - In 2011, a team of astronomers began using the planetary candidate "c" designation for a potential super-Earth at least 5.92 Earth-masses (Mayor et al, 2011, Table 3 and Table 4; and Segransan et al, 2011, in preparation). Planet c orbits HD 1461 at an average orbital distance of 0.112 AU with a period of 13.50 days with an eccentricity fixed at 0.

Planet "d?" - On December 14, 2009, a team of astronomers (including Eugenio J. Rivera, R. Paul Butler, Steven S. Vogt; Gregory Laughlin, Gregory W. Henry, and Stefano Meschiari) announced the possible detection of possibly a Neptune-class planet, based on radial-velocity observations with the Keck Observatory's High Resolution Echelle Spectrometer (HIRES) and the Anglo-Australian Telescope (U.C. Santa Cruz news release; Keck press release; and Rivera et al, 2009). Planetary candidate "d" appears to have 27.9 Earth-masses. It orbits HD 1461 at an average orbital distances of 1.16 AUs with a period of 446 days, with an eccentricity of e= 0.74 +/-0.13.

JPL, NASA



Larger image.



If confirmed, planetary candidate "d" could be rocky
or ice-rich like Neptune, unconfirmed
planetary candidate "d" probably hase a
thick gas envelope.

Planet "e?" - On December 14, 2009, a team of astronomers (including Eugenio J. Rivera, R. Paul Butler, Steven S. Vogt; Gregory Laughlin, Gregory W. Henry, and Stefano Meschiari) announced the possible detection of possibly a Saturn-class, based on radial-velocity observations with the Keck Observatory's High Resolution Echelle Spectrometer (HIRES) and the Anglo-Australian Telescope (U.C. Santa Cruz news release; Keck press release; and Rivera et al, 2009). Planetary candidate "e" has at least 87.1 Earth-masses. It appears to orbit HD 1461 at average orbital distance of around 5 AUs with a period of 5,017 days (or around 13.7 years) and an eccentricity e= 0.16 +/-0.29.

NASA

Larger image.

Planetary candidate "e" may have
somewhat near Saturn's mass.