You
have stumbled onto Jay Farihi's homepage...
Incriminating information:
I am a Professor in
the Astrophysics group at University College London, and a former (2012) Ernest
Rutherford Fellow. Prior to UCL, I was a
Senior Fellow at the Institute of Astronomy in Cambridge, and held postdoctoral
positions at the University of Leicester and Gemini Observatory North. My doctoral research was carried out at the
University of California, Los Angeles.
My main research activity is digging up evidence of terrestrial
planetary systems at stellar corpses known as white dwarfs. One might not
expect to find the surviving planetary systems around dead stars, but the
universe is full of surprises. In fact, it is likely we will learn more about
extrasolar terrestrial planets using white dwarfs than via any other method. This
is because cool white dwarfs have pure hydrogen and helium atmospheres, and
those stars with rocky planetary systems can become polluted by small yet
detectable amounts of heavy elements, such as metals. We can use this metal
pollution to measure the composition of the rocky planetary material, and even identify water.
I use the Hubble and
the Spitzer Space Telescopes to
analyze the rocky debris around white dwarfs; the current picture is that they
externally polluted with heavy elements from tidally destroyed asteroids. The parent bodies descend from large and
differentiated objects, and these may be leftover planetary building blocks or
fragments of major planets. The
compositions measured to date are similar to the material found in the inner
Solar System (i.e. like Earth!). Currently, we estimate that at least 20-30% of
all white dwarfs harbor terrestrial planetary
system remnants. Relevant publications and press releases can
be found below.
The early years:
As a graduate student, I worked with Eric Becklin & Ben
Zuckerman searching for low mass stellar and substellar companions to nearby
white dwarfs. The bulk of my thesis is published in an ApJ Supplement Series paper. If you want
all the gory details (they are both plentiful and colorful), you can find my
thesis here:
http://whitedwarf.org/theses/farihi.pdf
The central result of my thesis: a spectral type histogram of
low mass companions to white dwarfs. The drop off in companion frequency is
clearly above the minimum mass for hydrogen burning, which corresponds to an
early L dwarf spectral type / temperature at typical white dwarf ages of one to
a few Gyr. Our sensitivity is off the
chart. As with solar-type main sequence stars, intermediate mass stars (the
progenitors of white dwarfs) with brown dwarf companions are rare.
Passions, obsessions, the endless pursuit of knowledge:
The assembly and fate of planetary systems
Origin and evolution of low mass objects
The local cool white dwarf population
Digging in the stellar graveyard
I am fortunate to have several space-based research programs, as
well as talented students in our group. Many
of our results are posted below, with more on the way...
Opinions backed by evidence:
97) Planetesimals at DZ Stars I: Chondritic Compositions and a Massive Accretion
Event: astro-ph | MNRAS
96) An HST COS Ultraviolet Spectroscopic Survey of 311 DA White
Dwarfs. I. Fundamental Parameters and Comparative Studies: astro-ph | MNRAS
95) Discovery of Dipolar
Chromospheres in Two White Dwarfs: astro-ph | MNRAS
94) Measurement of Stellar and Substellar Winds Using White Dwarf Hosts: astro-ph | MNRAS
93) Two Substellar Survivor
Candidates; One Found and One Missing: astro-ph | MNRAS
92) Gaia White Dwarfs
within 40 pc - III. Spectroscopic Observations of New Candidates in the
Southern Hemisphere: astro-ph | MNRAS
91) The Gliese 86 Binary
System: A Warm Jupiter Formed in a Disk Truncated at 2 AU: astro-ph | AJ
90) Relentless and
Complex Transits from a Planetesimal Debris Disk: astro-ph | MNRAS | press | BBC
89) Collisions in a
Gas-Rich White Dwarf Planetary Debris Disc: astro-ph | MNRAS
88) Carbon-Enhanced
Stars with Short Orbital and Spin Periods: astro-ph | MNRAS
87) A Test of the
Planet-Star Unipolar Inductor for Magnetic White Dwarfs: astro-ph | MNRAS
86) Horizontal Spreading
of Planetary Debris Accreted by White Dwarfs:
astro-ph | MNRAS
85) White Dwarfs with
Planetary Remnants in the Era of Gaia
I. Six Emission Line Systems: astro-ph | MNRAS
84) GD 424, a Helium Atmosphere
White Dwarf with a Large Amount of Trace Hydrogen in the Process of Digesting a
Rocky Planetesimal: astro-ph | MNRAS
83) White Dwarf Pollution by Hydrated Planetary
Remnants: Hydrogen and Metals in WD J204713.76–125908.9: astro-ph | MNRAS
82) Gaia White Dwarfs within 40
pc. I. Spectroscopic Observations of New Candidates: astro-ph | MNRAS
81) The Dust Never Settles:
Collisional Production of Gas and Dust in Evolved Planetary Systems: astro-ph | MNRAS
80) A Word to the WISE:
Confusion Is Unavoidable for WISE-Selected
Infrared Excesses: astro-ph | ApJ
79) Interpretation and Diversity of Exoplanetary Material
Orbiting White Dwarfs: astro-ph |
MNRAS
78) A Chandra Study: Are Dwarf Carbon Stars Spun Up and Rejuvenated by Mass Transfer?: astro-ph | ApJ
77) The Unbiased
Frequency of Planetary Signatures around Single and Binary White Dwarfs using Spitzer and Hubble: astro-ph | MNRAS
76) A Planetesimal
Orbiting within the Debris Disc around a White Dwarf Star: astro-ph | Science
75) Most White
Dwarfs with Detectable Dust Discs Show Infrared Variability: astro-ph | MNRAS
74) Evidence for Bimodal Orbital Separations of White
Dwarf - Red Dwarf Binary Stars: astro-ph | MNRAS
73) Multi-Wavelength Observations of
the EUV Variable Metal-Rich White Dwarf GD 394: astro-ph | MNRAS
72) Broadening of Ly-alpha
by Neutral Helium in DBA White Dwarfs: astro-ph | MNRAS
71) Dust Production and
Depletion in Evolved Planetary Systems: astro-ph | MNRAS
70) Fast
Spectrophotometry of WD 1145+017: astro-ph | MNRAS
69) Infrared Variability
of Two Dusty White Dwarfs: astro-ph | ApJ
68) Dwarf Carbon Stars Are Likely Metal-Poor
Binaries and Unlikely Hosts to Carbon Planets: astro-ph | MNRAS
67) Evidence for Halo Kinematics among Cool Carbon-Rich
Dwarfs: astro-ph | MNRAS
66) Evidence for Eccentric, Precessing Gaseous Debris
in the Circumstellar Absorption toward WD 1145+017: astro-ph | ApJL
65) The First Post-Kepler Brightness Dips of KIC 8462852: astro-ph | ApJL
64) Periodic Optical
Variability and Debris Accretion in White Dwarfs: a Test for a Causal Connection:
astro-ph | MNRAS
63) Magnetism, X-rays,
and Accretion Rates in WD 1145+017 and other Polluted White Dwarf Systems: astro-ph | MNRAS
62) Magnetospherically-Trapped
Dust and a Possible Model for the Unusual Transits at WD 1145+017: astro-ph | MNRAS
61) Spectroscopic
Evolution of Disintegrating Planetesimals: Minutes to Months Variability in the
Circumstellar Gas Associated with WD 1145+017: astro-ph | ApJ
60) Trace Hydrogen in Helium Atmosphere
White Dwarfs as a Possible Signature of Water Accretion: astro-ph | MNRAS
59) Infrared Observations of White Dwarfs
and the Implications for the Accretion of Dusty Planetary Material: astro-ph | MNRAS
58) A Circumbinary Debris Disk in a Polluted White Dwarf System: astro-ph | Nature Astronomy | press
57) Solar Abundances of Rock Forming Elements, Extreme Oxygen
and Hydrogen in a Young Polluted White Dwarf: astro-ph | MNRAS
56) Carbon to Oxygen Ratios in Extrasolar Planetesimals: astro-ph | MNRAS
55)
Circumstellar Debris and Pollution at
White Dwarf Stars: astro-ph | NewAR | press
54) High-Speed Photometry of the Disintegrating Planetesimals
at WD 1145+017: Evidence for Rapid Dynamical Evolution: astro-ph | ApJ
53) Likely Detection of Water-Rich Asteroid
Debris in a Metal-Polluted White Dwarf: astro-ph | MNRAS
52) The Frequency and
Infrared Brightness of Circumstellar Discs at White Dwarfs: astro-ph | MNRAS
51) Signs of a Faint Disc Population
at Polluted White Dwarfs: astro-ph | MNRAS
50) ALMA and Herschel Observations of the Prototype Dusty and Polluted White
Dwarf G29-38: astro-ph | MNRAS
49) Heavy Metals in a Light White
Dwarf: Abundances of the Metal-Rich, Extremely Low-Mass GALEX J1717+6757: astro-ph | MNRAS
48) The Puzzling Source
IGR J17361-4441
in NGC 6388: A Possible Planetary Tidal Disruption Event: astro-ph | MNRAS
47) The Frequency of Planetary Debris at Young
White Dwarfs: astro-ph | A&A
46) Stochastic Accretion of Planetesimals onto
White Dwarfs. Constraints on the Mass Distribution of Accreted Material from
Atmospheric Pollution: astro-ph | MNRAS
45) Evidence for Water in the Rocky Debris of a
Disrupted Extrasolar Minor Planet: astro-ph | Science | press | BBC | Hubble | Nature
44) Evidence of
Rocky Planetesimals Orbiting Two Hyades Stars: astro-ph | MNRAS | press | BBC
43) Orbital and Evolutionary Constraints on the Planet Hosting
Binary GJ 86 from the Hubble Space
Telescope: astro-ph | MNRAS
42) The WIRED Survey III: An Infrared Excess around the
Eclipsing Post-Common Envelope Binary SDSS J030308.35+005443.7: astro-ph | ApJ
41) Precision Astrometry of the Exoplanet Host Candidate GD 66: astro-ph | MNRAS
40) The Chemical Diversity of Exoterrestrial Planetary Debris
Around White Dwarfs: astro-ph | MNRAS | press
39) Scars of Intense
Accretion Episodes at Metal-Rich White Dwarfs: astro-ph | MNRAS
38) Gaseous Material
Orbiting the Polluted White Dwarf HE 1349-2305: astro-ph | ApJ
37) The Origin of Circumstellar Features in the Spectra of Hot
DA White Dwarfs: astro-ph | MNRAS
36) Constraints
on the Lifetimes of Disks Resulting from Tidally Destroyed Rocky Planetary
Bodies: astro-ph | ApJ
35) A Trio of
Metal-Rich Dust and Gas Disks Found Orbiting Candidate White Dwarfs with K-Band Excess: astro-ph | MNRAS
34) An
Extremely Luminous Panchromatic Outburst from the Nucleus of a Distant Galaxy: astro-ph | Science | BBC
33) Evolutionary
Constraints on the Planet-Hosting Subgiant epsilon
Reticulum from its White Dwarf Companion: astro-ph | MNRAS
32) Accretion
of a Terrestrial-Like Minor Planet by a White Dwarf: astro-ph | ApJ
31) The
Magnetic and Metallic Degenerate G77-50: astro-ph | MNRAS
30) Possible
Signs of Water and Differentiation in a Rocky Exoplanetary Body: astro-ph | ApJL
29) White Dwarf -
Red Dwarf Systems Resolved with the Hubble
Space Telescope. II. Full Snapshot Survey Results: astro-ph | ApJS
28) A Detailed
Model Atmosphere Analysis of Cool White Dwarfs in the Sloan Digital Sky Survey: astro-ph | ApJS
27) Strengthening
the Case for Asteroidal Accretion: Evidence for Subtle and Diverse Disks at
White Dwarfs: astro-ph | ApJ
26) Does GD
356 Have a Terrestrial Planetary Companion?: astro-ph | MNRAS
25) Rocky
Planetesimals as the Origin of Metals in DZ Stars: astro-ph | MNRAS | press
24) IRTF
Observations of White Dwarfs with Possible Near-Infrared Excess: astro-ph | MNRAS
23) Deep
Imaging Survey of Young, Nearby Austral Stars. VLT / NACO Near-infrared Lyot-Coronographic
Observations: astro-ph | A&A
22) A Glimpse
of the End of the Dark Ages: The Gamma-Ray Burst of 23 April 2009 at Redshift 8.3:
astro-ph | Nature | BBC
21) X-Ray and
Infrared Observations of Two Externally-Polluted White Dwarfs: astro-ph | ApJ | press
20) PHL 5038: A Spatially Resolved White Dwarf - Brown Dwarf
Binary: astro-ph | A&A
19) Infrared Signatures of Disrupted Minor Planets at White
Dwarfs: astro-ph | ApJ | press | BBC
18) Six White Dwarfs with Circumstellar Silicates: astro-ph | AJ | press
17) Spitzer IRAC
Observations of White Dwarfs. II. Massive Planetary and Cold Brown Dwarf
Companions to Young and Old Degenerates: astro-ph | ApJ
16) Near-Infrared Constraints on the Presence of Warm Dust at
Metal-Rich Helium Atmosphere White Dwarfs: astro-ph | AJ
15) Spitzer IRAC
Observations of White Dwarfs. I. Warm Dust at Metal-Rich Degenerates: astro-ph | ApJ
14) A Near-Infrared Spectroscopic Study of the Accreting
Magnetic White Dwarf SDSS J121209.31+013627.7 and Its Substellar Companion: astro-ph | ApJ | press
13) Externally Polluted White Dwarfs with Dust Disks: astro-ph | ApJ
12) Infrared Emission from the Dusty Disk Orbiting GD 362, an
Externally Polluted White Dwarf: astro-ph | AJ | press
11) The Nature of the Close Magnetic White Dwarf - Probable
Brown Dwarf Binary SDSSJ121209.31+013627.7: astro-ph | MNRAS
10) HST NICMOS Imaging
of the Planetary-mass Companion to the Young Brown Dwarf 2MASSW J1207334-393254:
astro-ph | ApJ | press
9) White Dwarf - Red Dwarf Systems Resolved with the Hubble Space Telescope. I. First
Results: astro-ph | ApJ
8) Low-Luminosity Companions to White Dwarfs
(thesis work): astro-ph | ApJS
7) Mid-Infrared Observations of the White
Dwarf - Brown Dwarf Binary GD 1400: astro-ph | AJ
6) A Dusty Disk around GD 362, a White Dwarf with a Uniquely
High Photospheric Metal Abundance: astro-ph | ApJL | press
5) SSSPM J1549-3544 Is Not a White Dwarf: astro-ph | ApJL
4) Cool versus Ultracool White Dwarfs: astro-ph | AJ
3) A Possible Brown Dwarf Companion to the White Dwarf GD 1400: astro-ph | AJ
2) Discovery of an Ultracool White Dwarf Companion: astro-ph | ApJ
1) Mid-Infrared Observations of van Maanen 2: No Substellar
Companion: astro-ph | ApJL
Exchange of ideas:
Jay Farihi
Professor
Physics and Astronomy
University College London
London WC1E 6BT
United Kingdom
Phone: +44 203 549 5812
j dot farihi at ucl dot ac dot uk