J/AJ/165/114 SpecMatch-Emp isochrone analysis for 45 stars (Zuckerman+, 2023)
The Breakthrough Listen Search for Intelligent Life; A Laser Search Pipeline for
the Automated Planet Finder.
Zuckerman A., Ko Z., Isaacson H., Croft S., Price D., Lebofsky M.,
Siemion A.
<Astron. J., 165, 114 (2023)>
=2023AJ....165..114Z 2023AJ....165..114Z
ADC_Keywords: Spectra, optical; Effective temperatures; Abundances, [Fe/H];
Stars, ages; Stars, diameters; Stars, masses
Keywords: Search for extraterrestrial intelligence ; Technosignatures ;
Stellar spectral lines ; Astrobiology ; Stellar classification ;
High-resolution spectroscopy
Abstract:
The Search for Extraterrestrial Intelligence has traditionally been
conducted at radio wavelengths, but optical searches are
well-motivated and increasingly feasible due to the growing
availability of high-resolution spectroscopy. We present a data
analysis pipeline to search Automated Planet Finder (APF)
spectroscopic observations from the Levy Spectrometer for intense,
persistent, narrow-bandwidth optical lasers. We describe the
processing of the spectra, the laser search algorithm, and the results
of our laser search on 1983 spectra of 388 stars as part of the
Breakthrough Listen search for technosignatures. We utilize an
empirical spectra-matching algorithm called SpecMatch-Emp to produce
residuals between each target spectrum and a set of best-matching
catalog spectra, which provides the basis for a more sensitive search
than previously possible. We verify that SpecMatch-Emp performs well
on APF-Levy spectra by calibrating the stellar properties derived by
the algorithm against the SpecMatch-Emp library and against Gaia
catalog values. We leverage our unique observing strategy, which
produces multiple spectra of each target per night of observing, to
increase our detection sensitivity by programmatically rejecting
events that do not persist between observations. With our laser search
algorithm, we achieve a sensitivity equivalent to the ability to
detect an 84kW laser at the median distance of a star in our data set
(78.5ly). We present the methodology and vetting of our laser search,
finding no convincing candidates consistent with potential laser
emission in our target sample.
Description:
The Automated Planet Finder (APF) covers wavelengths between 3740 and
9700Å and has an average resolution of 95000. Observations for
Breakthrough Listen started in 2016, and observing time is pooled with
the California Planet Search (CPS) using a queue system managed by UC
Santa Cruz. Initially observing with 10% of telescope time, BL now
utilizes 20hr per semester allocated to BL targets as of 2022 January.
Spectra are taken with a decker size of 1x5".
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 72 45 Selected columns and rows from the results of
SpecMatch-Emp before isochrone analysis
table4.dat 98 45 Selected columns and rows from the results of
SpecMatch-Emp after isochrone analysis
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See also:
J/ApJ/767/94 : 1.1-1.9GHz SETI survey of KOIs. I. (Siemion+, 2013)
J/ApJ/844/102 : KIC star plxs from asteroseismology vs Gaia (Huber+, 2017)
J/AJ/154/107 : California-Kepler Survey (CKS). I. 1305 stars (Petigura+, 2017)
J/ApJ/836/77 : Library of high-S/N optical spectra of FGKM stars (Yee+, 2017)
J/AJ/159/280 : Gaia-Kepler stellar properties cat.I. KIC stars (Berger+, 2020)
Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 9 A9 --- Name Star identifier
11- 14 I4 K Teff [3430/6702] Effective temperature
16- 18 I3 K e_Teff [72/126] Error on Teff
20- 23 F4.2 [Rsun] [Rad] [0.4/4.43] log stellar radius
25- 29 F5.3 [Rsun] e_[Rad] [0.07/0.4] Error on [Rad]
31- 35 F5.2 [-] [Fe/H] [-0.41/0.15] log metallicity
37- 41 F5.3 [-] e_[Fe/H] [0.09] Error on [Fe/H]
43- 46 F4.2 [Msun] [Mass] [0.4/1.62] log stellar mass
48- 51 F4.2 [Msun] e_[Mass] [0.6] Error on [Mass]
53- 57 F5.2 [yr] [Age] [9.28/10] log stellar age
59- 62 F4.2 [yr] e_[Age] [0.23] Error on [Age]
64- 67 F4.2 cm/s2 logg [3.22/4.84] Surface gravity
69- 72 F4.2 cm/s2 e_logg [0.09] Error on logg
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 9 A9 --- Name Star identifier
11- 14 I4 K Teff [3540/6823] Effective temperature
16- 18 I3 K e_Teff [36/133] Negative error on Teff
20- 22 I3 K E_Teff [40/130] Positive error on Teff
24- 27 F4.2 [Rsun] [Rad] [0.37/6.37] log stellar radius
29- 32 F4.2 [Rsun] e_[Rad] [0.01/0.8] Negative error on [Rsun]
34- 37 F4.2 [Rsun] E_[Rad] [0.01/2] Positive error on [Rsun]
39- 42 F4.2 [-] [Fe/H] [0.01/0.4] log metallicity
44- 47 F4.2 [-] e_[Fe/H] [0.06/0.2] Negative error on [Fe/H]
49- 52 F4.2 [-] E_[Fe/H] [0.06/0.2] Positive error on [Fe/H]
54- 57 F4.2 [Msun] [Mass] [0.36/1.86] log stellar mass
59- 62 F4.2 [Msun] e_[Mass] [0.01/0.4] Negative error on [Mass]
64- 67 F4.2 [Msun] E_[Mass] [0.01/0.3] Positive error on [Mass]
69- 73 F5.2 [yr] [Age] [1.12/13.8] log stellar age
75- 78 F4.2 [yr] e_[Age] [0.1/7] Negative error on [Age]
80- 83 F4.2 [yr] E_[Age] [0.2/7] Positive error on [Age]
85- 88 F4.2 cm/s2 logg [3.07/4.84] Surface gravity
90- 93 F4.2 cm/s2 e_logg [0.01/0.2] Negative error on logg
95- 98 F4.2 cm/s2 E_logg [0.01/0.08] Positive error on logg
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History:
From electronic version of the journal
(End) Prepared by Coralie Fix [CDS], 17-Nov-2023