The intrinsic luminosity of young Jupiters is of high interest for planet formation theory. It is an observable quantity that is determined by important physical mechanisms during formation, namely the accretion shock structure, and even more fundamentally, the basic formation mechanism (core accretion or gravitational instability). We study the impact of the core mass on the post-formation entropy and luminosity of young giant planets forming via core accretion with a supercritical shock (cold accretion). For this, we conduct self-consistently coupled formation and evolution calculations of giant planets with masses between 1 and 12 Jovian masses and core masses between 20 and 120 Earth masses. We find that the post-formation luminosity of massive giant planets is very sensitive to the core mass. An increase of the core mass by a factor 6 results in an increase of the post-formation luminosity of a 10 Jovian mass planet by a factor 120. Due to this dependency, there is no single well defined post-formation luminosity for core accretion, but a wide range. For massive cores (~100 Earth masses), the post-formation luminosities of core accretion planets become so high that they approach those in the hot start scenario that is often associated with gravitational instability. For the mechanism to work, it is necessary that the solids are accreted before or during gas runaway accretion, and that they sink deep into the planet. We make no claims whether or not such massive cores can actually form in giant planets. But if yes, it becomes difficult to rule out core accretion as formation mechanism based solely on luminosity for directly imaged planets that are more luminous than predicted for low core masses. Instead of invoking gravitational instability as the consequently necessary formation mode, the high luminosity could also be caused simply by a more massive core.
Planetesimal accretion is a key source for heavy-element enrichment in giant planets. It has been suggested that Jupiter's enriched envelope is a result of planetesimal accretion during its growth assuming it formed in a massive planetesimal disk. In this study, we simulate Jupiter's formation in this scenario. We assume in-situ formation and perform N-body simulations to infer the solid accretion rate. We find that tens-Earth masses of planetesimals can be captured by proto-Jupiter during the rapid gas accretion phase. However, if several embryos are formed near Jupiter's core, which is an ex…
最近的{ \em Kepler}观测显示，在$0.02-0.2$ AU的内部，有大量的地球大小到海王星大小的“热”行星。我们认为，这些较小的行星是大质量巨行星的残余物，它们向内迁移的速度比它们收缩的速度要快。我们表明，这种破坏自然发生在行星形成的潮汐缩小假说的框架。我们发现，这种“热破裂”发生的特征行星-恒星分离是$R \approx 0.03-0.2$ AU。这个结果与行星的胚胎质量无关，但取决于圆盘中的吸积速率。在高增长率下，$\dot M \simgt 10^{-6}\msun$ yr $^{-1}$，胚胎不能足够快地收缩并被破坏。在后期，当生长速率下降到$\dot M \simlt 10^{-8} \msun$ yr $^{-1}$时，胚胎迁移足够慢而不被破坏。这些“迟到者”也许可以解释众所周知的热木星人口。如果I型迁移机制效率低下，那么我们的模型预测，当迁移率突然从II型转换到I型时，在$R\sim 0.1$ AU处会有行星堆积。
Jupiter's enhancement in nitrogen relative to hydrogen when compared to the Sun has been interpreted as evidence that its early formation occurred beyond the N$_{2}$ snowline ($\sim$ 20-40 AU). However, the rapid growth necessary to form Jupiter before the dissipation of the solar nebula would lead to the forming planet's core reaching very high temperatures ($>$1000 K), which would lead to it warming its surroundings. Here, we explore the effects of a luminous planetary core on the solids that it ultimately accretes. We find that a critical transition occurs where very hot (rapidly accreting)…
We report new photometric and spectroscopic observations of the K2-99 planetary system. Asteroseismic analysis of the short-cadence light curve from K2's Campaign 17 allows us to refine the stellar properties. We find K2-99 to be significantly smaller than previously thought, with $R_{\star} = 2.55\pm0.02$ $\mathrm{R_\odot}$. The new light curve also contains four transits of K2-99b, which we use to improve our knowledge of the planetary properties. We find the planet to be a non-inflated warm Jupiter, with $R_\mathrm{b} = 1.06 \pm 0.01$ $\mathrm{R_{Jup}}$. Sixty new radial velocity measuremen…
Isotope abundance ratios play an important role in astronomy and planetary sciences, providing insights in the origin and evolution of the Solar System, interstellar chemistry, and stellar nucleosynthesis. In contrast to deuterium/hydrogen ratios, carbon isotope ratios are found to be roughly constant (~89) in the Solar System, but do vary on galactic scales with 12C/13C~68 in the current local interstellar medium. In molecular clouds and protoplanetary disks, 12CO/13CO isotopologue ratios can be altered by ice and gas partitioning, low-temperature isotopic ion exchange reactions, and isotope-…
Coupled evolutions of the stellar obliquity, orbital distance, and planet's radius due to the Ohmic dissipation induced in a diamagnetic hot Jupiter around a magnetic T Tauri star
We report the discovery of TOI-4562 b (TIC-349576261), a Jovian planet orbiting a young F7V-type star, younger than the Praesepe/Hyades clusters (< $700$ Myr). This planet stands out because of its unusually long orbital period for transiting planets with known masses ($P_{\mathrm{orb}}$ = $225.11781^{+0.00025}_{-0.00022}$ days), and because it has a substantial eccentricity ($e$ = $0.76^{+0.02}_{-0.02}$). The location of TOI-4562 near the southern continuous viewing zone of TESS allowed observations throughout 25 sectors, enabling an unambiguous period measurement from TESS alone. Alongside t…
Linking atmospheric characteristics of planets to their formation pathways is a central theme in the study of extrasolar planets. Although the 12C/13C isotope ratio shows little variation in the solar system, the atmosphere of a super-Jupiter was recently shown to be rich in 13CO, possibly as a result of dominant ice accretion beyond the CO snowline during its formation. In this paper we aim to measure the 12CO/13CO isotopologue ratio of a young, isolated brown dwarf. While the general atmospheric characteristics of young, low mass brown dwarfs are expected to be very similar to those of super…
HIP 67522 b is a 17 Myr old, close-in ($P_{orb} = 6.96$ d), Jupiter-sized ($R = 10\,R_{\oplus}$) transiting planet orbiting a Sun like star in the Sco-Cen OB association. We present our measurement of the system's projected orbital obliquity via two spectroscopic transit observations using the CHIRON spectroscopic facility. We present a global model that accounts for large surface brightness features typical of such young stars during spectroscopic transit observations. With a value of $|λ| = 5.8^{+2.8\,\circ}_{-5.7}$, it is unlikely that this well-aligned system is the result of a high eccent…
We present the confirmation and characterization of three hot Jupiters, TOI-1181b, TOI-1516b, and TOI-2046b, discovered by the TESS space mission. The reported hot Jupiters have orbital periods between 1.4 and 2.05 days. The masses of the three planets are $1.18\pm0.14$ M$_{\mathrm{J}}$, $3.16\pm0.12$\, M$_{\mathrm{J}}$, and 2.30 $\pm 0.28$ M$_{\mathrm{J}}$, for TOI-1181b, TOI-1516b, and TOI-2046b, respectively. The stellar host of TOI-1181b is a F9IV star, whereas TOI-1516b and TOI-2046b orbit F main sequence host stars. The ages of the first two systems are in the range of 2-5 Gyrs. However,…
Unraveling the Mystery of the Peculiar and Young Hot Jupiter CoRoT-2b II: Phase Resolved Emission Spectroscopy with VLT/CRIRES+ and Gemini-S/IGRINS
University of Warwick（华威大学）；Université de Montréal（蒙特利尔大学）；Institut de Recherche en Astrophysique et Planétologie (IRAP)（天体物理学与行星学研究所在）；Instituto de Astrofísica de Andalucía (IAA-CSIC)（安达卢西亚天体物理研究所）；Department of Astronomy, University of Michigan（密歇根大学天文学系）
Unraveling the Mystery of the Peculiar and Young Hot Jupiter CoRoT-2b. I. H$_2$O and CO Detection from Dayside Observations with Gemini-S/IGRINS
Trottier Institute for Research on Exoplanets（系外行星特罗蒂尔研究所）；Université de Montréal（蒙特利尔大学）；University of Waterloo（滑铁卢大学）；Caltech（加州理工学院）；McGill University（麦吉尔大学）；Observatoire astronomique de l’Universit（大学天文台）
Detecting and characterising exoworlds around very young stars (age$<$10 Myr) are key aspects of exoplanet demographic studies, especially for understanding the mechanisms and timescales of planet formation and migration. However, detection using the radial velocity method alone can be very challenging, since the amplitude of the signals due to magnetic activity of such stars can be orders of magnitude larger than those induced even by massive planets. We observed the very young ($\sim$2 Myr) and very active star V830 Tau with the HARPS-N spectrograph to independently confirm and characterise …
Candidate free-floating super-Jupiters in the young sigma Orionis open cluster
在猎户座σ疏散星团中发现了自由漂浮的亚恒星候选者，其估计的理论质量低至约5个木星质量。随着与行星质量域重叠的增加，这些物体如何形成的问题变得重要。确定它们的数量密度以及是否存在质量截止极限对于了解它们的形成至关重要。我们建议在集群中寻找质量较低的物体，并确定低质量下质量函数的形状。使用新的和（重新分析的）已发表的IZJHKs[3.6]-[8.0]波段数据，面积为840弧分2，我们根据它们的预期星等和颜色，在J=19.5-21.5等范围内搜索LT型星团成员候选者。除了恢复T型天体S Ori 70和其他两个已知天体外，我们还发现了三个新的星团候选成员，S Ori 72-74，J=21等，距离星团中心12弧分以内。它们的理论质量为4（-2，+3）M_Jup，是太阳系外通过直接成像探测到的质量最小的自由漂浮天体之一。档案斯皮策[3.6]-[5.8]波段图像中的测光推断，S Ori 72是L/T过渡候选者，S Ori 73是T型候选者，遵循中红外预期的集群序列。最后，测光质量较低的L型候选星S Ori 74位于猎户座σ的一颗恒星成员的11.8角秒（~4250 AU）处，可能是一颗伴星。在完成J=21.1等的污染校正后，我们估计在6-4 M_Jup的质量区间内仍有0到2个星团成员。我们的结果表明，在低于~6木星质量的亚恒星质量谱中可能有一个周转，这可以通过更广泛和更深入的光度测量来进一步研究。
The Juno mission has provided an accurate determination of Jupiter's gravitational field, which has been used to obtain information about the planet's composition and internal structure. Several models of Jupiter's structure that fit the probe's data suggest that the planet has a diluted core, with a total heavy-element mass ranging from ten to a few tens of Earth masses (~5-15 % of the Jovian mass), and that heavy elements (elements other than H and He) are distributed within a region extending to nearly half of Jupiter's radius. Planet-formation models indicate that most heavy elements are a…
