On the emergent spectra of hot protoplanet collision afterglows

Eliza Miller-Ricci, Michael R. Meyer, Sara Seager, Linda Elkins-Tanton

Research output: Contribution to journalArticle

13 Citations (Scopus)

Abstract

We explore the appearance of terrestrial planets in formation by studying the emergent spectra of hot molten protoplanets during their collisional formation. While such collisions are rare, the surfaces of these bodies may remain hot at temperatures of 1000-3000 K for up to millions of years during the epoch of their formation (of duration 10-100 Myr). These objects are luminous enough in the thermal infrared to be observable with current and next-generation optical/IR telescopes, provided that the atmosphere of the forming planet permits astronomers to observe brightness temperatures approaching that of the molten surface. Detectability of a collisional afterglow depends on properties of the planet's atmosphere - primarily on the mass of the atmosphere. A planet with a thin atmosphere is more readily detected, because there is little atmosphere to obscure the hot surface. Paradoxically, a more massive atmosphere prevents one from easily seeing the hot surface, but also keeps the planet hot for a longer time. In terms of planetary mass, more massive planets are also easier to detect than smaller ones because of their larger emitting surface areas - up to a factor of 10 in brightness between 1 and 10 M planets. We present preliminary calculations assuming a range of protoplanet masses (1-10 M ), surface pressures (1-1000 bar), and atmospheric compositions, for molten planets with surface temperatures ranging from 1000 to 1800 K, in order to explore the diversity of emergent spectra that are detectable. While current 8 to 10 m class ground-based telescopes may detect hot protoplanets at wide orbital separations beyond 30 AU (if they exist), we will likely have to wait for next-generation extremely large telescopes or improved diffraction suppression techniques to find terrestrial planets in formation within several AU of their host stars.

Original languageEnglish (US)
Pages (from-to)770-780
Number of pages11
JournalAstrophysical Journal
Volume704
Issue number1
DOIs
StatePublished - 2009
Externally publishedYes

Fingerprint

protoplanets
afterglows
planets
planet
collision
collisions
atmospheres
hot surfaces
atmosphere
terrestrial planets
telescopes
atmospheric composition
planetary mass
brightness temperature
surface temperature
surface pressure
brightness
time measurement
retarding
diffraction

Keywords

  • Planetary systems

ASJC Scopus subject areas

  • Space and Planetary Science
  • Astronomy and Astrophysics

Cite this

On the emergent spectra of hot protoplanet collision afterglows. / Miller-Ricci, Eliza; Meyer, Michael R.; Seager, Sara; Elkins-Tanton, Linda.

In: Astrophysical Journal, Vol. 704, No. 1, 2009, p. 770-780.

Research output: Contribution to journalArticle

Miller-Ricci, Eliza ; Meyer, Michael R. ; Seager, Sara ; Elkins-Tanton, Linda. / On the emergent spectra of hot protoplanet collision afterglows. In: Astrophysical Journal. 2009 ; Vol. 704, No. 1. pp. 770-780.
@article{78aa1f9ff7d74608842f951c5b06d70e,
title = "On the emergent spectra of hot protoplanet collision afterglows",
abstract = "We explore the appearance of terrestrial planets in formation by studying the emergent spectra of hot molten protoplanets during their collisional formation. While such collisions are rare, the surfaces of these bodies may remain hot at temperatures of 1000-3000 K for up to millions of years during the epoch of their formation (of duration 10-100 Myr). These objects are luminous enough in the thermal infrared to be observable with current and next-generation optical/IR telescopes, provided that the atmosphere of the forming planet permits astronomers to observe brightness temperatures approaching that of the molten surface. Detectability of a collisional afterglow depends on properties of the planet's atmosphere - primarily on the mass of the atmosphere. A planet with a thin atmosphere is more readily detected, because there is little atmosphere to obscure the hot surface. Paradoxically, a more massive atmosphere prevents one from easily seeing the hot surface, but also keeps the planet hot for a longer time. In terms of planetary mass, more massive planets are also easier to detect than smaller ones because of their larger emitting surface areas - up to a factor of 10 in brightness between 1 and 10 M ⊕ planets. We present preliminary calculations assuming a range of protoplanet masses (1-10 M ⊕), surface pressures (1-1000 bar), and atmospheric compositions, for molten planets with surface temperatures ranging from 1000 to 1800 K, in order to explore the diversity of emergent spectra that are detectable. While current 8 to 10 m class ground-based telescopes may detect hot protoplanets at wide orbital separations beyond 30 AU (if they exist), we will likely have to wait for next-generation extremely large telescopes or improved diffraction suppression techniques to find terrestrial planets in formation within several AU of their host stars.",
keywords = "Planetary systems",
author = "Eliza Miller-Ricci and Meyer, {Michael R.} and Sara Seager and Linda Elkins-Tanton",
year = "2009",
doi = "10.1088/0004-637X/704/1/770",
language = "English (US)",
volume = "704",
pages = "770--780",
journal = "Astrophysical Journal",
issn = "0004-637X",
publisher = "IOP Publishing Ltd.",
number = "1",

}

TY - JOUR

T1 - On the emergent spectra of hot protoplanet collision afterglows

AU - Miller-Ricci, Eliza

AU - Meyer, Michael R.

AU - Seager, Sara

AU - Elkins-Tanton, Linda

PY - 2009

Y1 - 2009

N2 - We explore the appearance of terrestrial planets in formation by studying the emergent spectra of hot molten protoplanets during their collisional formation. While such collisions are rare, the surfaces of these bodies may remain hot at temperatures of 1000-3000 K for up to millions of years during the epoch of their formation (of duration 10-100 Myr). These objects are luminous enough in the thermal infrared to be observable with current and next-generation optical/IR telescopes, provided that the atmosphere of the forming planet permits astronomers to observe brightness temperatures approaching that of the molten surface. Detectability of a collisional afterglow depends on properties of the planet's atmosphere - primarily on the mass of the atmosphere. A planet with a thin atmosphere is more readily detected, because there is little atmosphere to obscure the hot surface. Paradoxically, a more massive atmosphere prevents one from easily seeing the hot surface, but also keeps the planet hot for a longer time. In terms of planetary mass, more massive planets are also easier to detect than smaller ones because of their larger emitting surface areas - up to a factor of 10 in brightness between 1 and 10 M ⊕ planets. We present preliminary calculations assuming a range of protoplanet masses (1-10 M ⊕), surface pressures (1-1000 bar), and atmospheric compositions, for molten planets with surface temperatures ranging from 1000 to 1800 K, in order to explore the diversity of emergent spectra that are detectable. While current 8 to 10 m class ground-based telescopes may detect hot protoplanets at wide orbital separations beyond 30 AU (if they exist), we will likely have to wait for next-generation extremely large telescopes or improved diffraction suppression techniques to find terrestrial planets in formation within several AU of their host stars.

AB - We explore the appearance of terrestrial planets in formation by studying the emergent spectra of hot molten protoplanets during their collisional formation. While such collisions are rare, the surfaces of these bodies may remain hot at temperatures of 1000-3000 K for up to millions of years during the epoch of their formation (of duration 10-100 Myr). These objects are luminous enough in the thermal infrared to be observable with current and next-generation optical/IR telescopes, provided that the atmosphere of the forming planet permits astronomers to observe brightness temperatures approaching that of the molten surface. Detectability of a collisional afterglow depends on properties of the planet's atmosphere - primarily on the mass of the atmosphere. A planet with a thin atmosphere is more readily detected, because there is little atmosphere to obscure the hot surface. Paradoxically, a more massive atmosphere prevents one from easily seeing the hot surface, but also keeps the planet hot for a longer time. In terms of planetary mass, more massive planets are also easier to detect than smaller ones because of their larger emitting surface areas - up to a factor of 10 in brightness between 1 and 10 M ⊕ planets. We present preliminary calculations assuming a range of protoplanet masses (1-10 M ⊕), surface pressures (1-1000 bar), and atmospheric compositions, for molten planets with surface temperatures ranging from 1000 to 1800 K, in order to explore the diversity of emergent spectra that are detectable. While current 8 to 10 m class ground-based telescopes may detect hot protoplanets at wide orbital separations beyond 30 AU (if they exist), we will likely have to wait for next-generation extremely large telescopes or improved diffraction suppression techniques to find terrestrial planets in formation within several AU of their host stars.

KW - Planetary systems

UR - http://www.scopus.com/inward/record.url?scp=70549085060&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=70549085060&partnerID=8YFLogxK

U2 - 10.1088/0004-637X/704/1/770

DO - 10.1088/0004-637X/704/1/770

M3 - Article

VL - 704

SP - 770

EP - 780

JO - Astrophysical Journal

JF - Astrophysical Journal

SN - 0004-637X

IS - 1

ER -