Optical–infrared flares and radio afterglows by Jovian planets inspiraling into their host stars

Yamazaki, Ryo; Hayasaki, Kimitake; Loeb, Abraham

doi:10.1093/mnras/stw3207

Cited by 33 publications

(11 citation statements)

References 81 publications

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“…Dynamically induced stellar collisions or close interactions in a dense stellar cluster 18 could in principle produce a series of optical transients. Similarly, the collision of a jovian planet with a main sequence star 19,20 or a terrestrial planet with a white dwarf star 21 could generate an optical transient with a peak luminosity comparable to that observed for the HFF14Spo events, although it is unclear whether the UV/optical emission could match the observed HFF14Spo light curves. These scenarios warrant further scrutiny, so that predictions of the light curve shape and anticipated rates can be more rigorously compared to the HFF14Spo observations.…”

Section: Peak Absolute Magnitudementioning

confidence: 94%

Two peculiar fast transients in a strongly lensed host galaxy

Rodney

Balestra²,

Bradač

et al. 2018

Nat Astron

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A massive galaxy cluster can serve as a magnifying glass for distant stellar populations, with strong gravitational lensing exposing details in the lensed background galaxies that would otherwise be undetectable. The MACS J0416.1-2403 cluster (hereafter MACS0416) is one of the most efficient lenses in the sky, and in 2014 it was observed with high-cadence imaging from the Hubble Space Telescope (HST). Here we describe two unusual transient events that appeared behind MACS0416 in a strongly lensed galaxy at redshift z = 1.0054 ± 0.0002. These transients-designated HFF14Spo-NW and HFF14Spo-SE and collectively nicknamed "Spock"-were faster and fainter than any supernova (SN), but significantly more luminous than a classical nova. They reached peak luminosities of ∼ 10 41 erg s −1 (M AB < −14 mag) in 5 rest-frame days, then faded below detectability in roughly the same time span. Models of the cluster lens suggest that these events may be spatially coincident at the source plane, but are most likely not temporally coincident. We find that HFF14Spo can be explained as a luminous blue variable (LBV), a recurrent nova (RN), or a pair of stellar microlensing events. To distinguish between these hypotheses will require a clarification of the positions of nearby critical curves, along with high-cadence monitoring of the field that could detect new transient episodes in the host galaxy.

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Section: Peak Absolute Magnitudementioning

confidence: 94%

Two peculiar fast transients in a strongly lensed host galaxy

Rodney

Balestra²,

Bradač

et al. 2018

Nat Astron

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“…Upon engulfment of a companion, immediate signatures may include cooling emission from shock-heated ejecta (Metzger et al 2012;Yamazaki et al 2017), and radio afterglows from ejecta-interstellar medium 3.5 3.6 3.7 3. interactions (Yamazaki et al 2017). On a dynamical timescale the stellar envelope expands to return to quasi-hydrostatic equilibrium as orbital decay does work against the gravitational binding energy of the envelope.…”

Section: Emergent Luminosity Versus Orbital Decay Powermentioning

confidence: 99%

“…Others have discussed the role of digested planets in depositing angular momentum into the stellar envelope and enhancing stellar rotation (Soker 1998;Siess & Livio 1999b;Zhang & Penev 2014;Privitera et al 2016a,b), enhancing surface magnetic field (Privitera et al 2016c), and polluting surface abundances with planetary material (Sandquist et al 1998;Siess & Livio 1999b;Sandquist et al 2002;Aguilera-Gómez et al 2016b,a). Finally, some authors have estimated the role of engulfment events in producing transients from stellar ejecta (Soker & Tylenda 2006;Metzger et al 2012;Yamazaki et al 2017), or in shaping planetary nebulae from ejecta (De Marco & Soker 2011).…”

Section: Introductionmentioning

confidence: 99%

Planetary Engulfment in the Hertzsprung–Russell Diagram

MacLeod

Cantiello

Soares-Furtado

2018

ApJL

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Planets accompany most sun-like stars. The orbits of many are sufficiently close that they will be engulfed when their host stars ascend the giant branch. This Letter compares the power generated by orbital decay of an engulfed planet to the intrinsic stellar luminosity. Orbital decay power is generated by drag on the engulfed companion by the surrounding envelope. As stars ascend the giant branch their envelope density drops and so does the power injected through orbital decay, scaling approximately as L decay ∝ R −9/2 * . Their luminosity, however, increases along the giant branch. These opposed scalings indicate a crossing, where L decay = L * . We consider the engulfment of planets along isochrones in the Hertzsprung-Russell (H-R) diagram. We find that the conditions for such a crossing occur around L * ≈ 10 2 L (or a ≈ 0.1 au) for Jovian planetary companions. The consumption of closer-in giant planets, such as hot Jupiters, leads to L decay L * , while more distant planets such as warm Jupiters, a ≈ 0.5 au, lead to minor perturbations of their host stars with L decay L * . Our results map out the parameter space along the giant branch in the H-R Diagram where interaction with planetary companions leads to significant energetic disturbance of host stars.

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“…The angular momentum deposited in the stellar envelop can enhance significantly stellar rotation [16,21,[24][25][26][27]. Stellar ejecta can produce transients [16,[28][29][30]. Ref.…”

Section: Engulfing Of Gas Giants By Giant Stars and Its Impact On Mix...mentioning

confidence: 99%

Giants eating giants: Mass loss and giant planets modifying the luminosity of the Tip of the Giant Branch

Jimenez,

Jorgensen,

Verde

2020

Preprint

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During the red giant phase, stars loose mass at the highest rate since birth. The mass-loss rate is not fixed, but varies from star-to-star by up to 5%, resulting in variations of the star's luminosity at the tip of the red giant branch (TRGB). Also, most stars, during this phase, engulf part of their planetary system, including their gas giant planets. Gas giant planet masses range between 0.1 to 2% of the host star mass. The engulfing of their gas giants planets can modify their luminosity at the TRGB, i.e. the point at which the He-core degeneracy is removed. We show that the increase in mass of the star by the engulfing of the gas giant planets only modifies the luminosity of a star at the TRGB by less than 0.1%, while metallicity can modify the luminosity of a star at the TRGB by up to 0.5%. However, the increase in turbulence of the convective envelope of the star, i.e., modification of the mixing length, has a more dramatic effect, on the star's luminosity, which we estimate could be as large as 5%. The effect is always in the direction to increase the turbulence and thus the mixing length which turns into a systematic decrease of the luminosity of the star at the TRGB. We find that the star-to-star variation of the mass-loss rate will dominate the variations in the luminosity of the TRGB with a contribution at the 5% level. If the starto-star variation is driven by environmental effects -as it is reasonable to assume-, the same effects can potentially create an environmentally-driven mean effect on the luminosity of the tip of the red giant branch of a galaxy. Finally, we touch upon how to infer the frequency, and identify the engulfment, of exoplanets in low-metallicity RGB stars through high resolution spectroscopy as well as how to quantify mass loss rate distributions from the morphology of the horizontal branch.

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Optical–infrared flares and radio afterglows by Jovian planets inspiraling into their host stars

Cited by 33 publications

References 81 publications

Two peculiar fast transients in a strongly lensed host galaxy

Two peculiar fast transients in a strongly lensed host galaxy

Planetary Engulfment in the Hertzsprung–Russell Diagram

Giants eating giants: Mass loss and giant planets modifying the luminosity of the Tip of the Giant Branch

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