Abstract
We report the confirmation of three exoplanets transiting TOI-4010 (TIC-352682207), a metal-rich K dwarf observed by the Transiting Exoplanet Survey Satellite in Sectors 24, 25, 52, and 58. ...We confirm these planets with the High Accuracy Radial velocity Planet Searcher for the Northern Hemisphere radial velocity observations and measure their masses with 8−12% precision. TOI-4010 b is a sub-Neptune (
P
= 1.3 days,
R
p
=
3.02
−
0.08
+
0.08
R
⊕
,
M
p
=
11.00
−
1.27
+
1.29
M
⊕
) in the hot-Neptune desert, and is one of the few such planets with known companions. Meanwhile, TOI-4010 c (
P
= 5.4 days,
R
p
=
5.93
−
0.12
+
0.11
R
⊕
,
M
p
=
20.31
−
2.11
+
2.13
M
⊕
) and TOI-4010 d (
P
= 14.7 days,
R
p
=
6.18
−
0.14
+
0.15
R
⊕
,
M
p
=
38.15
−
3.22
+
3.27
M
⊕
) are similarly sized sub-Saturns on short-period orbits. Radial velocity observations also reveal a super-Jupiter-mass companion called TOI-4010 e in a long-period, eccentric orbit (
P
∼ 762 days and
e
∼ 0.26 based on available observations). TOI-4010 is one of the few systems with multiple short-period sub-Saturns to be discovered so far.
Abstract
K2-136 is a late-K dwarf (0.742 ± 0.039
M
⊙
) in the Hyades open cluster with three known, transiting planets and an age of 650 ± 70 Myr. Analyzing K2 photometry, we found that planets ...K2-136b, c, and d have periods of 8.0, 17.3, and 25.6 days and radii of 1.014 ± 0.050
R
⊕
, 3.00 ± 0.13
R
⊕
, and 1.565 ± 0.077
R
⊕
, respectively. We collected 93 radial velocity (RV) measurements with the High-Accuracy Radial-velocity Planet Searcher for the Northern hemisphere (HARPS-N) spectrograph (Telescopio Nazionale Galileo) and 22 RVs with the Echelle SPectrograph for Rocky Exoplanets and Stable Spectroscopic Observations (ESPRESSO) spectrograph (Very Large Telescope). Analyzing HARPS-N and ESPRESSO data jointly, we found that K2-136c induced a semi-amplitude of 5.49 ± 0.53 m s
−1
, corresponding to a mass of 18.1 ± 1.9
M
⊕
. We also placed 95% upper mass limits on K2-136b and d of 4.3 and 3.0
M
⊕
, respectively. Further, we analyzed Hubble Space Telescope and XMM-Newton observations to establish the planetary high-energy environment and investigate possible atmospheric loss. K2-136c is now the smallest planet to have a measured mass in an open cluster and one of the youngest planets ever with a mass measurement. K2-136c has ∼75% the radius of Neptune but is similar in mass, yielding a density of
3.69
−
0.56
+
0.67
g cm
−3
(∼2–3 times denser than Neptune). Mass estimates for K2-136b (and possibly d) may be feasible with more RV observations, and insights into all three planets’ atmospheres through transmission spectroscopy would be challenging but potentially fruitful. This research and future mass measurements of young planets are critical for investigating the compositions and characteristics of small exoplanets at very early stages of their lives and providing insights into how exoplanets evolve with time.
Abstract
Measured spectral shifts due to intrinsic stellar variability (e.g., pulsations, granulation) and activity (e.g., spots, plages) are the largest source of error for extreme-precision ...radial-velocity (EPRV) exoplanet detection. Several methods are designed to disentangle stellar signals from true center-of-mass shifts due to planets. The Extreme-precision Spectrograph (EXPRES) Stellar Signals Project (ESSP) presents a self-consistent comparison of 22 different methods tested on the same extreme-precision spectroscopic data from EXPRES. Methods derived new activity indicators, constructed models for mapping an indicator to the needed radial-velocity (RV) correction, or separated out shape- and shift-driven RV components. Since no ground truth is known when using real data, relative method performance is assessed using the total and nightly scatter of returned RVs and agreement between the results of different methods. Nearly all submitted methods return a lower RV rms than classic linear decorrelation, but no method is yet consistently reducing the RV rms to sub-meter-per-second levels. There is a concerning lack of agreement between the RVs returned by different methods. These results suggest that continued progress in this field necessitates increased interpretability of methods, high-cadence data to capture stellar signals at all timescales, and continued tests like the ESSP using consistent data sets with more advanced metrics for method performance. Future comparisons should make use of various well-characterized data sets—such as solar data or data with known injected planetary and/or stellar signals—to better understand method performance and whether planetary signals are preserved.
Small planets on close-in orbits tend to exhibit envelope mass fractions of either effectively zero or up to a few percent depending on their size and orbital period. Models of thermally driven ...atmospheric mass loss and of terrestrial planet formation in a gas-poor environment make distinct predictions regarding the location of this rocky/nonrocky transition in period–radius space. Here we present the confirmation of TOI-1235 b (P = 3.44 days, r(p)=1.738 (+0.087, -0.076) Rꚛ), a planet whose size and period are intermediate between the competing model predictions, thus making the system an important test case for emergence models of the rocky/nonrocky transition around early M dwarfs (R(s) = 0.630 ± 0.015 Rꙩ, M(s) = 0.640 ± 0.016 Mꙩ}$). We confirm the TESS planet discovery using reconnaissance spectroscopy, ground-based photometry, high-resolution imaging, and a set of 38 precise radial velocities (RVs) from HARPS-N and HIRES. We measure a planet mass of 6.91 (+0.75, -0.85) Mꚛ, which implies an iron core mass fraction of 20 (+15,-12)% in the absence of a gaseous envelope. The bulk composition of TOI-1235 b is therefore consistent with being Earth-like, and we constrain an H/He envelope mass fraction to be <0.5% at 90% confidence. Our results are consistent with model predictions from thermally driven atmospheric mass loss but not with gas-poor formation, suggesting that the former class of processes remains efficient at sculpting close-in planets around early M dwarfs. Our RV analysis also reveals a strong periodicity close to the first harmonic of the photometrically determined stellar rotation period that we treat as stellar activity, despite other lines of evidence favoring a planetary origin P= 21.8(+0.9, _0.8) days, m(p)sin i= 13.0 (+3.8,-5.3) Mꚛ) that cannot be firmly ruled out by our data.
K2-136 is a late-K dwarf (\(0.742\pm0.039\) M\(_\odot\)) in the Hyades open cluster with three known, transiting planets and an age of \(650\pm70\) Myr. Analyzing K2 photometry, we found that planets ...K2-136b, c, and d have periods of \(8.0\), \(17.3\), and \(25.6\) days and radii of \(1.014\pm0.050\) R\(_\oplus\), \(3.00\pm0.13\) R\(_\oplus\), and \(1.565\pm0.077\) R\(_\oplus\), respectively. We collected 93 radial velocity measurements (RVs) with the HARPS-N spectrograph (TNG) and 22 RVs with the ESPRESSO spectrograph (VLT). Analyzing HARPS-N and ESPRESSO data jointly, we found K2-136c induced a semi-amplitude of \(5.49\pm0.53\) m s\(^{-1}\), corresponding to a mass of \(18.1\pm1.9\) M\(_\oplus\). We also placed \(95\)% upper mass limits on K2-136b and d of \(4.3\) and \(3.0\) M\(_\oplus\), respectively. Further, we analyzed HST and XMM-Newton observations to establish the planetary high-energy environment and investigate possible atmospheric loss. K2-136c is now the smallest planet to have a measured mass in an open cluster and one of the youngest planets ever with a mass measurement. K2-136c has \(\sim\)75% the radius of Neptune but is similar in mass, yielding a density of \(3.69^{+0.67}_{-0.56}\) g cm\(^{-3}\) (\(\sim\)2-3 times denser than Neptune). Mass estimates for K2-136b (and possibly d) may be feasible with more RV observations, and insights into all three planets' atmospheres through transmission spectroscopy would be challenging but potentially fruitful. This research and future mass measurements of young planets are critical for investigating the compositions and characteristics of small exoplanets at very early stages of their lives and providing insights into how exoplanets evolve with time.
We report the confirmation of three exoplanets transiting TOI-4010 (TIC-352682207), a metal-rich K dwarf observed by TESS in Sectors 24, 25, 52, and 58. We confirm these planets with HARPS-N radial ...velocity observations and measure their masses with 8 - 12% precision. TOI-4010 b is a sub-Neptune (\(P = 1.3\) days, \(R_{p} = 3.02_{-0.08}^{+0.08}~R_{\oplus}\), \(M_{p} = 11.00_{-1.27}^{+1.29}~M_{\oplus}\)) in the hot Neptune desert, and is one of the few such planets with known companions. Meanwhile, TOI-4010 c (\(P = 5.4\) days, \(R_{p} = 5.93_{-0.12}^{+0.11}~R_{\oplus}\), \(M_{p} = 20.31_{-2.11}^{+2.13}~M_{\oplus}\)) and TOI-4010 d (\(P = 14.7\) days, \(R_{p} = 6.18_{-0.14}^{+0.15}~R_{\oplus}\), \(M_{p} = 38.15_{-3.22}^{+3.27}~M_{\oplus}\)) are similarly-sized sub-Saturns on short-period orbits. Radial velocity observations also reveal a super-Jupiter-mass companion called TOI-4010 e in a long-period, eccentric orbit (\(P \sim 762\) days and \(e \sim 0.26\) based on available observations). TOI-4010 is one of the few systems with multiple short-period sub-Saturns to be discovered so far.
Measured spectral shifts due to intrinsic stellar variability (e.g., pulsations, granulation) and activity (e.g., spots, plages) are the largest source of error for extreme precision radial velocity ...(EPRV) exoplanet detection. Several methods are designed to disentangle stellar signals from true center-of-mass shifts due to planets. The EXPRES Stellar Signals Project (ESSP) presents a self-consistent comparison of 22 different methods tested on the same extreme-precision spectroscopic data from EXPRES. Methods derived new activity indicators, constructed models for mapping an indicator to the needed RV correction, or separated out shape- and shift-driven RV components. Since no ground truth is known when using real data, relative method performance is assessed using the total and nightly scatter of returned RVs and agreement between the results of different methods. Nearly all submitted methods return a lower RV RMS than classic linear decorrelation, but no method is yet consistently reducing the RV RMS to sub-meter-per-second levels. There is a concerning lack of agreement between the RVs returned by different methods. These results suggest that continued progress in this field necessitates increased interpretability of methods, high-cadence data to capture stellar signals at all timescales, and continued tests like the ESSP using consistent data sets with more advanced metrics for method performance. Future comparisons should make use of various well-characterized data sets -- such as solar data or data with known injected planetary and/or stellar signals -- to better understand method performance and whether planetary signals are preserved.
Small planets on close-in orbits tend to exhibit envelope mass fractions of either effectively zero or up to a few percent depending on their size and orbital period. Models of thermally-driven ...atmospheric mass loss and of terrestrial planet formation in a gas-poor environment make distinct predictions regarding the location of this rocky/non-rocky transition in period-radius space. Here we present the confirmation of TOI-1235 b (\(P=3.44\) days, \(r_p=1.738^{+0.087}_{-0.076}\) R\(_{\oplus}\)), a planet whose size and period are intermediate between the competing model predictions thus making the system an important test case for emergence models of the rocky/non-rocky transition around early M dwarfs (\(R_s=0.630\pm 0.015\) R\(_{\odot}\), \(M_s=0.640\pm 0.016\) M\(_{\odot}\)). We confirm the TESS planet discovery using reconnaissance spectroscopy, ground-based photometry, high-resolution imaging, and a set of 38 precise radial-velocities from HARPS-N and HIRES. We measure a planet mass of \(6.91^{+0.75}_{-0.85}\) M\(_{\oplus}\), which implies an iron core mass fraction of \(20^{+15}_{-12}\)% in the absence of a gaseous envelope. The bulk composition of TOI-1235 b is therefore consistent with being Earth-like and we constrain a H/He envelope mass fraction to be \(<0.5\)% at 90% confidence. Our results are consistent with model predictions from thermally-driven atmospheric mass loss but not with gas-poor formation, suggesting that the former class of processes remain efficient at sculpting close-in planets around early M dwarfs. Our RV analysis also reveals a strong periodicity close to the first harmonic of the photometrically-determined stellar rotation period that we treat as stellar activity, despite other lines of evidence favoring a planetary origin (\(P=21.8^{+0.9}_{-0.8}\) days, \(m_p\sin{i}=13.0^{+3.8}_{-5.3}\) M\(_{\oplus}\)) that cannot be firmly ruled out by our data.
We present the confirmation of two new planets transiting the nearby mid-M dwarf LTT 3780 (TIC 36724087, TOI-732, \(V=13.07\), \(K_s=8.204\), \(R_s\)=0.374 R\(_{\odot}\), \(M_s\)=0.401 M\(_{\odot}\), ...d=22 pc). The two planet candidates are identified in a single TESS sector and are validated with reconnaissance spectroscopy, ground-based photometric follow-up, and high-resolution imaging. With measured orbital periods of \(P_b=0.77\) days, \(P_c=12.25\) days and sizes \(r_{p,b}=1.33\pm 0.07\) R\(_{\oplus}\), \(r_{p,c}=2.30\pm 0.16\) R\(_{\oplus}\), the two planets span the radius valley in period-radius space around low mass stars thus making the system a laboratory to test competing theories of the emergence of the radius valley in that stellar mass regime. By combining 63 precise radial-velocity measurements from HARPS and HARPS-N, we measure planet masses of \(m_{p,b}=2.62^{+0.48}_{-0.46}\) M\(_{\oplus}\) and \(m_{p,c}=8.6^{+1.6}_{-1.3}\) M\(_{\oplus}\), which indicates that LTT 3780b has a bulk composition consistent with being Earth-like, while LTT 3780c likely hosts an extended H/He envelope. We show that the recovered planetary masses are consistent with predictions from both photoevaporation and from core-powered mass loss models. The brightness and small size of LTT 3780, along with the measured planetary parameters, render LTT 3780b and c as accessible targets for atmospheric characterization of planets within the same planetary system and spanning the radius valley.
After nuclear factor (NF)-κB activation, a complex network of negative feedback loops ensures that the termination of the NF-κB response occurs in a highly organized manner. Recent results show that ...signals initiated during the induction phase already program a default termination procedure that enables temporally and spatially regulated NF-κB deactivation. All negative feedback mechanisms occur with a characteristic time delay, thereby permitting full NF-κB function during the interim period. Some proteins that direct termination are produced directly in response to NF-κB activation, whereas others are activated via inducible binding or by protein stabilization. Another time-delaying strategy of NF-κB feedback inhibitory proteins relies on their ability to function as timers and molecular clockworks with the intrinsic property to terminate their own activity within a preset period.
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