The Lick Planet Search: 1987 - 2011

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The Lick Planet Search: 1987 - 2011

Post by Shellface on 29th October 2013, 4:56 pm

The Twenty-Five Year Lick Planet Search

The Lick planet search program began in 1987 when the first spectrum of τ Ceti was taken with an iodine cell and the Hamilton Spectrograph. Upgrades to the instrument improved the Doppler precision from about 10 m/s in 1992 to about 3 m/s in 1995. The project detected dozens of exoplanets with orbital periods ranging from a few days to several years. The Lick survey identified the first planet in an eccentric orbit (70 Virginis) and the first multi-planet system around a normal main sequence star (Upsilon Andromedae). These discoveries advanced our understanding of planet formation and orbital migration. Data from this project helped to quantify a correlation between host star metallicity and the occurrence rate of gas giant planets. The program also served as a test bed for innovation with testing of a tip-tilt system at the coudé focus and fiber scrambler designs to stabilize illumination of the spectrometer optics. The Lick planet search with the Hamilton spectrograph effectively ended when a heater malfunction compromised the integrity of the iodine cell. Here, we present more than 14,000 velocities for 386 stars that were surveyed between 1987 and 2011.
There goes the longest-running high precision RV instrument. A list of the spectrometer's discoveries and confirmations from its main sample is presented in section 7, edited here:
51 Pegasi b (confirmation)
70 Virginis b
47 Ursae Majoris b, c, d
55 Cancri Ab, c, d, e, f
τ Boötis Ab
υ Andromedae Ab, c, d, e
16 Cygni Bb
Gliese 876 b, c
HD 195019 Ab
HD 217107 b, c
HD 89744 Ab
HD 12661 b, c
HD 92788 b
HD 38529 Ab, c
HD 136118 b (Brown Dwarf)
HD 50554 b (confirmation)
HD 106252 b (confirmation)
HD 3651 Ab
HD 40979 Ab
HD 30562 b
HD 86264 b
HD 87883 b
HD 89307 b
HD 148427 b
HD 196885 Ab (confirmation, sort of)
But, alas. This is not the end for Lick spectrographs:
Since we expected that the Automated Planet Finder on a new 2.4-m telescope at Lick would soon come online, we elected to terminate the program on the Hamilton spectrograph.
With that in mind, this paper releases all of the radial velocities obtained for the stars of the main Lick-Hamilton survey (this does not include the giant and subgiant survey targets) to the public.
We share this legacy of data and lessons learned with the astronomical community and with future planet hunters.
I'll try to update this thread when the full edition of this paper goes up, presumably on iopscience, which will hopefully include all of the 14000 velocities.


Last edited by Shellface on 30th October 2013, 3:45 pm; edited 1 time in total (Reason for editing : absolutely no reason at all.)

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Re: The Lick Planet Search: 1987 - 2011

Post by Sirius_Alpha on 29th October 2013, 6:54 pm

Odd that they mention 55 Cnc g. Wasn't the e planet discovered by HET?

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Re: The Lick Planet Search: 1987 - 2011

Post by Shellface on 29th October 2013, 7:17 pm

I think g is a typo as e isn't listed. e was announced with HET data (McArthur et al. (2004)), but the paper made significant use of the available Lick and ELODIE datasets. Also, e's signal was also already significant in the 2002 Lick data alone, with a FAP of  1.1 × 10−6 according to McArthur et al., so Lick certainly made some contribution.

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Re: The Lick Planet Search: 1987 - 2011

Post by Sirius_Alpha on 29th October 2013, 7:18 pm

Gotcha, that makes sense. Thanks.

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Re: The Lick Planet Search: 1987 - 2011

Post by Lazarus on 30th October 2013, 2:19 pm

Alas? What's so bad about it not being the end?
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Re: The Lick Planet Search: 1987 - 2011

Post by Shellface on 30th October 2013, 3:46 pm

coughs entirely unsuspiciously

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Re: The Lick Planet Search: 1987 - 2011

Post by Lazarus on 30th October 2013, 3:57 pm

Wink
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Re: The Lick Planet Search: 1987 - 2011

Post by PlutonianEmpire on 30th October 2013, 6:49 pm

Considering I'm incredibly dense-headed, I still don't get it. Razz

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Re: The Lick Planet Search: 1987 - 2011

Post by Shellface on 19th December 2013, 12:37 pm

The paper's up on iopscience, be it paywalled. Paywalls on iopscience last a year from the publishing date, right? If so, the big release is gonna be at the end of 2014! Cool

PlutonianEmpire wrote:Considering I'm incredibly dense-headed, I still don't get it. Razz
I originally wrote "But, alas, this is not the end for Lick spectrographs", which would suggest that having more spectrographs is a woeful thing - and that most certainly not the case!

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Re: The Lick Planet Search: 1987 - 2011

Post by Shellface on 30th January 2015, 7:54 pm

Well, I'm a bit late, but the paper isn't paywalled anymore. It'll take some time to process the data, but in the meantime here's something I've been waiting to see for a few years now: the Lick RV curve for 94 Ceti A (HD 19994 A).



94 Ceti A (F8V-IV) had a planet discovered by the CORALIE team around 2000 and then published by Mayor et al. (2004). More data was added by Wittenmyer et al. (2009), which resulted in revisions of the planetary parameters.

The star was on the Lick RV survey from its inception (see Cumming et al. (1999)) to its end. Though the star is relatively hot for an RV survey (6200 K) and a fairly fast rotator for its spectral type (18.3 km/s), it is bright (V = 5) so spectra of the star have good S/N. Despite the long timescale of observations and good RV precision, the Lick data has not previously been analysed in literature, so this is the first public analysis of the RVs I am aware of.

parameterunitMayor et al. (2004)Wittenmyer et al. (2009)This work
perioddays535.7 ± 3.1466.2 ± 1.7460.8 ± 2.4
eccentricity0.30 ± 0.040.063 ± 0.0620.176 ± 0.075
ω°41 ± 8346 ± 55337 ± 36
M sin iMJ1.681.37 ± 0.121.10 ± 0.10
aAU1.421.305 ± 0.0161.295 ± 0.018

The Lick data - the first timeseries that spans more than ~3 orbital periods of the planet - requires a fairly large linear trend of 5.15 ± 0.40 m/s/yr. This is likely due the stellar companion (94 Ceti B, ~M2V) that lies at ~150 AU. The ORB6 catalogue lists a (very preliminary) orbit for the binary with P = 1420 yr, a = 6.77", and i = 114.1°. While searching for the planetary signal with relative astrometry, Röll et al. (2010) determined that the secondary is itself a binary with P ≈ 740 d and a ≈ 0.07". This period is not an integer multiple of the planetary orbital period, so the minor binary orbit is probably not "faking" the planetary orbit (ie. Morais et al. (2008)).

The RV trend on the primary, at the major orbital period, results in an m sin i of ~0.90 M. For i = 114.1°, this gives m ≈ 0.99 M, which is consistent with the ~0.96 M derived from the minor binary's orbit. As the mass of an M2 dwarf is about 0.5 M, this implies the minor binary has nearly equal components.

If we assume that the planetary orbit is aligned with the major stellar orbit, then m = 1.21 ± 0.11 MJ, ignoring the error on i. The planet seems to be a typical AU Jovian (which is the term that I made up to refer to the population of giant planets centred around 1 AU), though it is in a relatively tight multiple and one of the few planets in a triple system.

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Re: The Lick Planet Search: 1987 - 2011

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